Tag: biomass energy

The key to sustainable forests? Thinking globally and managing locally

1 December 2022

Sustainable bioenergy

Key takeaways:

  • Working forests, where wood products are harvested, are explicitly managed to balance environmental and economic benefits, while encouraging healthy, growing forests that store carbon, provide habitats for wildlife, and space for recreation.
  • But there is no single management technique. The most effective methods vary depending on local conditions.
  • By employing locally appropriate methods, working forests have grown while supporting essential forestry industries and local economies.
  • Forests in the U.S. South, British Columbia, and Estonia all demonstrate how local management can deliver both environmental and economic wins.

Forests are biological, environmental, and economic powerhouses. Collectively they are home to most of the planet’s terrestrial biodiversity. They are responsible for absorbing 7.6 billion tonnes of carbon dioxide (CO2) equivalent per year, or roughly 1.5 times the amount of CO2 produced by the United States on an annual basis. And working forests, which are actively managed to generate revenue from wood products industries, are important drivers for the global economy, employing over 13 million people worldwide and generating $600 billion annually.

But as important as forests are globally, the key to maximizing working forests’ potential lies in smart, active forest management. While 420 million hectares of forest have been lost since 1990 through conversion to other land uses such as for agriculture, many working forests are actually growing both larger and healthier due to science-based management practices.

The best practices in working forests balance economic, social, and environmental benefits. But just as importantly, they are tailored to local conditions and framed by appropriate regional regulations, guidance, and best-practice.

The following describes how three different regions, from which Drax sources its biomass, manage their forests for a sustainable future.

British Columbia: Managing locally for global climate change

British Columbia is blanketed by almost 60 million hectares of forest – an area larger than France and Germany combined. Over 90% of the forest land is owned by Canada’s government, meaning the province’s forests are managed for the benefit of the Canadian people and in collaboration with First Nations.

From the province’s expanse of forested land, less than half a percent (0.36%) is harvested each year, according to government figures. This ensures stable, sustainable forests. However, there’s a need to manage against natural factors.

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In 2017, 2018, and 2020 catastrophic fires ripped through some of British Columbia’s most iconic forest areas, underscoring the threat climate change poses to the area’s natural resources. One response was to increase the removal of stands of trees in the forest, harvesting the large number of dead or dying trees created by pests that have grown more common in a warming climate.

By removing dead trees, diseased trees, and even some healthy trees, forest managers can reduce the amount of potential fuel in the forest, making devastating wildfires less likely. There are also commercial advantages to this strategy. Most of the trees removed are low quality and not suitable for processing into lumber. These trees can, however, still be used commercially to produce biomass wood pellets that offer a renewable alternative to fossil fuels. This means local communities don’t just get safer forests, they get safer forests that support the local economy.

The United States: Thinning for healthier forests

The U.S. South’s forests have expanded rapidly in recent decades, largely due to growth in working forests on private land. Annual forest growth in the region more than doubled from 193 million cubic metres of wood in 1953 to 408 million cubic meters by 2015.

This expansion has occurred thanks to active forest product markets which incentivise forest management investment. In the southern U.S. thinning is critical to managing healthy and productive pine forests.

Thinning is an intermediate harvest aimed at reducing tree density to allocate more resources, like nutrients, sunlight, and water, to trees which will eventually become valuable sawtimber. Thinning not only increases future sawtimber yields, but also improves the forest’s resilience to pest, disease, and wildfire, as well as enhancing understory diversity and wildlife habitat.

 

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While trees removed during thinning are generally undersized or unsuitable for lumber, they’re ideal for producing biomass wood pellets. In this way, the biomass market creates an incentive for managers to engage in practices that increase the health and vigour of forests on their land.

The results speak for themselves: across U.S. forestland the volume of annual net timber growth 36% higher than the volume of annual timber removals.

A managed working forest in the US South

Estonia: Seeding the future

Though Estonia is not a large country, approximately half of it is covered in trees, meaning forestry is integral to the country’s way of life. Historically, harvesting trees has been an important part of the national economy, and the government has established strict laws to ensure sustainable management practices.

These regulations have helped Estonia increase its overall forest cover from about 34% 80 years ago to over 50% today. And, as in the U.S. South, the volume of wood harvested from Estonia’s forests each year is less than the volume added by tree growth.

Sunrise and fog over forest landscape in Estonia

Sunrise and fog over forest landscape in Estonia

Estonia has managed to increase its growing forest stock by letting the average age of its forests increase. This is partially due to Estonia having young, fast-growing forests in areas where tree growth is relatively new. But it is also due to regulations that require harvesters to leave seed trees.

Seed trees are healthy, mature trees, the seeds from which become the forest’s next generation. By enforcing laws that ensure seed trees are not harvested, Estonia is encouraging natural regeneration of forests. As in the U.S. South protecting these seed trees from competition for water and nutrients means removing smaller trees in the area. While these smaller trees may not all be suitable for lumber, they are a suitable feedstock for biomass. It means managing for natural regeneration can still have economic, as well as environmental, advantages.

Different methods, similar results

Laws, landownership, and forestry practices differ greatly between the U.S. South, British Columbia, and Estonia, but all three are excellent examples of how local forest management contributes to healthy rural economies and sustained forest coverage.

While there are many different strategies for creating a balance between economic and environmental interests, all successful strategies have something in common: They encourage healthy, growing forests.

Alabama Cluster Catchment Area Analysis

16 February 2022

Sustainable bioenergy

The area of timberland in the Alabama cluster catchment area has remained stable over the last 20 years, increasing slightly from 4.08 million ha to 4.16 million ha, an increase of 79 thousand hectares.  This area represents 79.6% of the total land area in 2020, up from 78.1% in 2020.  The total area of forestland and woodland was 86% of the catchment area in 2020, with farmland making up 13% and urban areas 1%.  This land base can be considered to be heavily forested and dominated by timberland.

Figure 1: Land Use Type – Alabama cluster

The timberland area is classified by growth rate potential, capable of achieving a minimum of 0.57 m3/ha/year.  More than 95% of the timberland area is in private ownership.  This proportion has remained stable since 2000 as shown in Figure 2.

Figure 2: Timberland Ownership Profile – Alabama cluster

The total standing volume, the amount of carbon stored in the forest area, has increased by 115 million m3 since 2000 an increase of 30%. Most of this increase has occurred since 2010, with 90 million m3 added to the inventory since this time, reflecting the maturing age class of the forest resource as it passes through the peak growth phase.  Almost all of this increase has been in the softwood pine forest area, with a combined increase of 86 million m3 since 2010.  Pine saw-timber and chip-n-saw both increased by 46% since 2010 and pine pulpwood by 25% over the same period. Suggesting that the average tree size is getting larger as the forest matures.

Figure 3: Standing Volume by Product Class – Alabama cluster

One measure of the sustainability of harvesting levels is to compare average annual growth against removals.  This comparison gives a growth drain ratio (GDR).  Where removals are equal to or lower than growth (a GDR of 1 or more) this is a measure of sustainability, where the ratio falls below 1, this can indicate that harvesting levels are not sustainable in the long-term.  Figure 4 shows that all pine product classes have a positive GDR since 2010.  In particular the pine pulpwood GDR ratio is in excess of 2 suggesting that there is a substantial surplus of this product category.  By contrast, the hardwood GDR for both saw-timber and pulpwood are both lower than 1 suggesting that harvesting levels for hardwood species should be reduced until growth can recover.

Figure 4: Growth Drain Ratio by Product Class – Alabama cluster

Figure 5 shows the maturing age class of the forest area, charting the change in annual surplus and deficit in each product class.  The trend shows that harvesting of pine saw-timber from 2000 to 2008 represented a deficit of growth compared to harvesting removals.  This indicates an immature forest resource with a low quantity of forest categorised as saw-timber, therefore harvesting volume in mature stands outweighed the growth in mid-rotation stands.  As the forest aged, and more standing timber grew into the saw-timber category, the surplus of annual growth compared to removals increased.  Saw-timber growth in 2020 was 3 million m3 higher than in 2000.  The surplus of pine pulpwood has remained positive and has increased substantially from 3 million m3 in 2000 to 6.5 million m3 in 2020 despite harvesting levels increasing slightly over this period.

Figure 5: Annual Surplus/Deficit of Growth and Removal by Product Class – Alabama Cluster

Biomass demand began in 2008 at a very small scale, representing just 0.5% of total pulpwood demand in the catchment area.  From around 2013 it began to increase and reached peak in 2015 with a total demand of 724,000 tons of pulpwood in that year, representing 8.1% of total pulpwood demand in the catchment area.  After that time, demand for pulpwood declined as pellet mills switched to mill residuals.  The latest data on pulpwood demand shows that the biomass sectors made up just 2.8% of total pulpwood demand in 2020 with just over 216,000 tonnes of total demand.  This demonstrates that the biomass and wood pellet sector is a very small component of the market in this region and unlikely to influence forest management decision making, as shown in Figure 6.

Figure 6: Pulpwood Demand by Market – Alabama Cluster

Pine pulpwood stumpage prices have declined significantly since a peak in 2013, falling from an annual high of $9.46 when demand was strongest to just $4.12 in 2020 as demand for pine pulpwood declined in 2020.  Pine saw-timber prices have seen a similar decline from a high point in the early 2000’s to a plateau from 2011 onwards.  Saw-timber stumpage more than halved in value over this period from $49 per ton to $22 per ton.  This can have a significant impact on forest management objectives and decision making.

Figure 7: Stumpage Price Change by Product Category – Alabama Cluster

Detailed below are the summary findings from Hood Consulting on the impact of biomass demand on key issues in the Alabama cluster catchment area.

Is there any evidence that bioenergy demand has caused the following:

Deforestation?

No. US Forest Service (USFS) data shows that total timberland area has held steady and averaged roughly 4,172,000 hectares in the Alabama Cluster catchment area since Alabama Pellets-Aliceville started up in late-2012. More importantly, planted pine timberland (the predominant source of roundwood utilized by the bioenergy industry for wood pellet production) has increased more than 75,000 hectares (+4.9%) in the catchment area since Alabama Pellets’ startup in 2012.

A change in management practices (rotation lengths, thinnings, conversion from hardwood to pine)?

Inconclusive. Changes in management practices have occurred in the catchment area over the last two decades. However, the evidence is inconclusive as to whether increased demand attributed to bioenergy has caused or is responsible for those changes.

Clearcuts and thinnings are the two major types of harvests that occur in this region, both of which are long-standing, widely used methods of harvesting timber. TimberMart-South (TMS) data shows that the prevalence of thinnings temporarily increased in the Alabama Cluster market (from 2007-2013) due to the weakening of pine sawtimber markets. Specifically, challenging market conditions saw pine sawtimber stumpages prices decline from an average of $47 per ton from 2000-2006 to just over $23 per ton in 2011, or a roughly 50% decrease from 2000-2006 average levels. This led many landowners to refrain from clearcutting (a type of harvest which typically removes large quantities of pine sawtimber), as they waited for pine sawtimber prices to improve. However, pine sawtimber stumpage prices never recovered and have held between $22 and $25 per ton since 2011. Ultimately, landowners returned to more ‘normal’ management practices by 2014, with thinnings falling back in line with pre-2007 trends.

The catchment area has also experienced some conversion. Specifically, from 2000-2020, planted pine timberland increased more than 460,000 hectares while natural hardwood and mixed pine-hardwood timberland decreased a combined 390,000 hectares. Note that the increase in planted pine timberland and decrease in natural hardwood/mixed pine-hardwood timberland over this period were both gradual and occurred simultaneously. This suggests a management trend in which natural timber stands are converted to plantation pine following final harvest. It’s also important to note that there is little evidence that links these changes to increased demand from bioenergy, as this conversion trend begun years prior to the startup of Alabama Pellets and continued nearly unchanged following the pellet mill’s startup.

Diversion from other markets?

No. Demand for softwood (pine) sawlogs increased an estimated 12% in the catchment area from 2012-2020. Also, there is no evidence that increased demand from bioenergy has caused a diversion from other softwood pulpwood markets (i.e. pulp/paper). Also, even though softwood pulpwood demand not attributed to bioenergy is down 14% since Alabama Pellets-Aliceville’s startup in 2012, there is no evidence that increased demand from bioenergy has caused this decrease. Rather, the decrease in demand from non-bioenergy sources is due to a combination of reduced product demand (and therefore reduced production) and increased utilization of sawmill residuals.

An unexpected or abnormal increase in wood prices?

No. The startup of Alabama Pellets-Aliceville added roughly 450,000 metric tons of softwood pulpwood demand to the catchment area from 2012-2016, and this increase in demand coincided with essentially no change in delivered pine pulpwood (PPW) price over this same period. Ultimately, the additional demand placed on the catchment area following the startup of Alabama Pellets-Aliceville was offset by a decrease in demand from other sources from 2012-2016, and, as a result, delivered PPW prices remained nearly unchanged.

However, the Aliceville facility was shut down for a majority of 2017 due to the catastrophic failure of a key piece of environmental equipment, and this was followed by Alabama Pellets’ strategic decision to transition to residual-consumption only beginning in 2018, which eliminated more than 360,000 metric tons of annual softwood pulpwood demand from 2016-2018. Over this same period, softwood pulpwood demand from other sources also decreased nearly 360,000 metric tons. So, with the elimination of roughly 720,000 metric tons of annual softwood pulpwood demand from all sources from 2016-2018, delivered PPW prices in the catchment area proceeded to decrease more than 6% over this period. Since 2018, total softwood pulpwood demand has increased roughly 4% in the catchment area (due to increases in demand from non-bioenergy sources), and this increase that has coincided with a simultaneous 4% increase in delivered PPW price.

Statistical analysis did identify a positive relationship between softwood biomass demand and delivered PPW price. However, the relationship between delivered PPW price and non-biomass-related softwood pulpwood demand was found to be stronger, which is not unexpected given that pine pulpwood demand not attributed to bioenergy has accounted for 94% of total pine pulpwood demand in the catchment area since 2012. Ultimately, the findings provide evidence that PPW price is influenced by demand from all sources – not just from bioenergy or from pulp/paper, but from both.

Furthermore, note that Alabama Pellets’ shift to residual-consumption only beginning in 2018 resulted in no increase in pine sawmill chip prices, as the price of pine sawmill chips in the Alabama Cluster catchment area rather decreased from 2018-2020, despite a more than 100,000-metric ton increase in pine sawmill chip consumption by the Aliceville mill over this period.

A reduction in growing stock timber?

No. From 2012 (the year Alabama Pellets started up) to 2020, total growing stock inventory increased an average of 2.6% per year (+22% total) in the Alabama Cluster catchment area. Specifically, inventories of pine sawtimber and pine chip-n-saw increased 41% and 40%, respectively, while pine pulpwood (PPW) inventory increased 25% over this same period.

A reduction in the sequestration rate of carbon?

No. US Forest Service (USFS) data shows the average annual growth rate of total growing stock timber in the Alabama Cluster catchment area increased from 6.0% in 2012 to 6.2% in 2020, suggesting that the sequestration rate of carbon also increased slightly over this period.

Note that the increase in overall growth rate (and therefore increase in the sequestration rate of carbon) can be linked to gains in pine timberland and associated changes with the catchment area forest. Specifically, growth rates decline as timber ages, so the influx of new pine timberland (due to the conversion of both hardwood forests and cropland) has resulted in just the opposite, with the average age of softwood (pine) growing stock inventory decreasing from an estimated 35.4 years of age in 2000 to 33.2 years of age in 2010 and to 32.2 years of age in 2020 (total growing stock inventory decreased from 41.9 to 41.0 and to 40.4 years of age over these periods).

An increase in harvesting above the sustainable yield capacity of the forest area?

No. Growth-to-removals (G:R) ratios, which compare annual timber growth to annual timber removals, provides a measure of market demand relative to supply as well as a gauge of market sustainability. In 2020, the latest available, the G:R ratio for pine pulpwood (PPW), the predominant timber product utilized by the bioenergy sector, equaled 3.26 (recall that a value greater than 1.0 indicates sustainable harvest levels).

Moreover, note that the PPW G:R ratio has increased in the catchment area since the Aliceville mill’s startup in 2012, despite the associated increases in pine pulpwood demand. In this catchment area, pine pulpwood demand from non-bioenergy sources decreased more than 860,000 metric tons from 2012 to 2020, and this decrease more than offset any increase in demand from bioenergy.

Impact of bioenergy demand on:

Timber growing stock inventory

Neutral. According to USFS data, inventories of pine pulpwood (PPW) increased 25% in the catchment area from 2012-2020, and this increase in PPW inventory can be linked to both increases in pine timberland and harvest levels below the sustainable yield capacity of the forest area. Specifically, pine timberland (both planted and natural combined) increased more than 185,000 hectares in the catchment area from 2012-2020. Over this same period, annual harvests of PPW were 65% below maximum sustainable levels.

Timber growth rates

Neutral. The average annual growth rate of total growing stock timber increased from 6.0% in 2012 to 6.2% in 2020 in the Alabama Cluster catchment area, despite pine pulpwood (PPW) growth rate decreasing from 15.1% to 12.5% over this period. However, this decrease in PPW growth rate was not due to increased demand attributed to bioenergy but rather to the aging of PPW within its product group and its natural movement along the pine growth rate curve. Specifically, USFS data indicates the average age of PPW inventory in the catchment area increased from an estimated 13.4 years of age in 2012 to 13.6 years of age in 2020.

Forest area

Neutral. In the Alabama Cluster catchment area, total forest (timberland) area remained nearly unchanged (decreasing only marginally) from 2012-2020. However, pine timberland – the predominant source of roundwood utilized by the bioenergy industry for wood pellet production – increased more than 185,000 hectares over this period, and this increase can be linked to several factors, including conversion from both hardwood and mixed pine-hardwood forests as well as conversion from cropland.

Specifically, the more than 185,000-hectare increase in pine timberland from 2012-2020 coincided with a roughly 197,000-hectare decrease in hardwood/mixed pine-hardwood timberland and a more than 8,000-hectare decrease in cropland over this period. Furthermore, statistical analysis confirmed these inverse relationships, identifying strong negative correlations between pine timberland area and both hardwood/mixed pine-hardwood timberland area and cropland in the catchment area from 2012-2020.

Wood prices

Negative/Neutral. Softwood pulpwood demand attributed to bioenergy increased from roughly 80,000 metric tons in 2012 (the year Alabama Pellets-Aliceville started up) to more than 655,000 metric tons in 2015 (the year biomass demand reached peak levels). However, this roughly 575,000-metric ton increase in softwood biomass demand coincided with essentially no change in delivered pine pulpwood (PPW) price – which averaged $26.40 per ton in 2012 and $26.39 per ton in 2015. Ultimately, the additional demand placed on this catchment area following the startup of Alabama Pellets-Aliceville was offset by a more than 680,000-metric ton decrease in demand from other sources over this same period, and, as a result, delivered PPW prices remained nearly unchanged. Also note that Alabama Pellets’ strategic shift to consume residuals only (a transition that begun in 2018 and had been completed by 2019) resulted in a nearly 480,000-metric ton decrease in softwood biomass demand in the catchment area from 2015 to 2020. Over this same period, softwood pulpwood demand from other sources decreased more than 180,000 metric tons. In total, softwood pulpwood demand from all sources decreased more than 660,000 metric tons from 2015 to 2020, and this decrease in demand resulted in delivered PPW prices decreasing 5% over this period.

Statistical analysis did identify a positive relationship between softwood biomass demand and delivered PPW price. However, the relationship between delivered PPW price and non-biomass-related softwood pulpwood demand was found to be stronger, which is not unexpected given that pine pulpwood demand not attributed to bioenergy has accounted for 94% of total pine pulpwood demand in the catchment area since 2012. Ultimately, the findings provide evidence that PPW price is influenced by demand from all sources – not just from bioenergy or from pulp/paper, but from both.

Markets for solid wood products

Positive. In the Alabama Cluster catchment area, demand for softwood sawlogs used to produce lumber and other solid wood products has increased an estimated 12% since 2012, and this increase in softwood lumber production has consequentially resulted in the increased production of sawmill residuals (i.e. chips, sawdust, and shavings) – by-products of the sawmilling process and materials utilized by Alabama Pellets to produce wood pellets.

Moreover, the increased availability of sawmill residuals and lower relative cost compared to roundwood (after chipping and other processing costs are considered) led Alabama Pellets to make a strategic shift to utilize residuals only for wood pellet production beginning in 2019. So, not only has Alabama Pellets benefited from the greater availability of this lower-cost sawmill by-product, but lumber producers have also benefited, as Alabama Pellets has provided an additional outlet for these producers and their by-products.

Read the full report: Alabama Cluster Catchment Area Analysis

This is part of a series of catchment area analyses around the forest biomass pellet plants supplying Drax Power Station with renewable fuel. Others in the series can be found here. 

What is sustainable forest management?

18 January 2022

Sustainable bioenergy

Sustainable forest management is frequently defined in terms of providing a balance of social, environmental, and economic benefits, not just for today but for the future too. It might be seen as the practice of maintaining forests to ensure they remain healthy, absorb more carbon than they release, and can continue to be enjoyed and used by future generations.

To achieve this, foresters apply science, knowledge, and standards that help ensure forests continue to play an important role in the wellbeing of people and the planet.

Managed forests, also called working forests, fulfil a variety of environmental, social, and economic functions. These range from forests managed to attract certain desired wildlife species, to forests grown to provide saw timber and reoccurring revenue for landowners.

How are forests sustainably managed?

How forests are managed depends on landowner goals – managing for recreation and wildlife, focusing on maximising production of wood products, or both. Each forest requires management tailored to its owner’s or manager’s objectives.

There are many ways to manage forests to keep them healthy – there is no ‘one size fits all’ – but keeping track of how they are doing can be tricky. One alternative for monitoring forests is to use satellite imagery.

One common sustainable forestry practice is thinning, which involves periodically removing smaller, unhealthy, or diseased trees to enable stronger ones to thrive. Thinning reduces competition between trees for resources like sunlight and water, and it can also help promote biodiversity by creating more space for other forest flora.

The wood removed from forests through thinning is sometimes not high-quality enough to be used in industries such as construction or furniture. However, the biomass industry can use it to make compressed wood pellets; a feedstock for renewable source electricity.

By providing a market for low-quality wood, pellet production encourages landowners to carry out thinnings. This practice improves the health of the forest, and helps support better growth, greater carbon storage, and creates more valuable woodland.

Fast facts

What are the environmental benefits of sustainably managed forests?

Through their ability to act as carbon sinks, forests are an important part of meeting global climate goals like the Paris Agreement and the UK’s own target of reaching net zero emissions by 2050.

When managed effectively through thinning or active harvesting, and replanting and regeneration, forests can often sequester – or absorb and store – more carbon than forests that are left untouched, increasing productivity and improving planting material.

Harvesting trees before they reach an age when growth slows or plateaus can help prevent fire damage, pests, and disease, so timing of final cutting is important. Though the vast majority of timber from such cutting will go to other markets (construction, furniture etc) and secure higher prices from those markets, being able to sell lower quality wood for biomass provides the landowner with some extra revenue.

Sustainably managed forests also help achieve other environmental goals, such as sustaining biodiversity, protecting sensitive sites and providing clean air and water. Managed forests also have substantial water absorption capacity preventing flooding by slowing the flow of sudden downpours and helping to prevent nearby rivers and streams from overfilling.

Wood from working forests also help tackle climate change in that high-value wood from harvested trees can be used to make timber for the construction or furniture sectors. These wood products lock up carbon for extended periods of time, and the wood can be used at end-of life to displace fossil fuels. Using wood also means materials such as concrete, bricks or steel are not used, and these materials have a large carbon footprint compared to wood.

What are the socioeconomic benefits of sustainably managed forests?

There are also social and economic benefits to managing forests. Sustainably managed working forests make vital contributions both to people and to the planet.

The commercial use of wood in industries like furniture and construction drives revenue for landowners. This encourages landowners to continue to replant forests and manage them in a sustainable way that continues to deliver returns.

Healthy forests can also improve living standards for local communities for jobs and helping to address unemployment in rural regions. Managed forests can also improve access for recreation. On a larger scale, sustainable forestry can offer a valuable export for regions and nations and foster trade between countries.

Go deeper 

Forests, net zero and the science behind biomass

22 December 2021

Sustainable bioenergy

Tackling climate change and spurring a global transition to net zero emissions will require collaboration between science and industry. New technologies and decarbonisation methods must be rooted in scientific research and testing.

Drax has almost a decade of experience in using biomass as a renewable source of power. Over that time, our understanding around the effectiveness of bioenergy, its role in improving forest health and ability to deliver negative emissions, has accelerated.

Research from governments and global organisations, such as the UN’s Intergovernmental Panel on Climate Change (IPCC) increasingly highlight sustainably sourced biomass and bioenergy’s role in achieving net zero on a wide scale.

The European Commission has also highlighted biomass’ potential to provide a solution that delivers both renewable energy and healthy, sustainably managed forests.  Frans Timmermans, the executive vice-president of the European Commission in charge of the European Green Deal has emphasised it’s importance in bringing economies to net zero, saying: “without biomass, we’re not going to make it. We need biomass in the mix, but the right biomass in the mix.”

The role of biomass in a sustainable future

Moving away from fossil fuels means building an electricity system that is primarily based on renewables. Supporting wind and solar, by providing electricity at times of low sunlight or wind levels, will require flexible sources of generation, such as biomass, as well as other technologies like increased energy storage.

In the UK, the Climate Change Committee’s (CCC) Sixth Carbon Budget report lays out its Balanced Net Zero Pathway. In this lead scenario, the CCC says that bioenergy can reduce fossil emissions across the whole economy by 2 million tonnes of CO2 or equivalent emissions (MtCO2e) per year by 2035, increasing to 2.5 MtCO2e in 2045.

Foresters in working forest, Mississippi

Foresters in working forest, Mississippi

Biomass is also expected to play a crucial role in supplying biofuels and hydrogen production for sectors of the global economy that will continue to use fuel rather than electricity, such as aviation, shipping and industrial processes. The CCC’s Balanced Net Zero Pathway suggest that enough low-carbon hydrogen and bioenergy will be needed to deliver 425 TWh of non-electric power in 2050 – compared to the 1,000 TWh of power fossil fuels currently provide to industries today.

However, bioenergy can only be considered to be good for the climate if the biomass used comes from sustainably managed sources. Good forest management practises ensure that forests remain sustainable sources of woody biomass and effective carbon sinks.

A report co-authored by IPCC experts examines the scientific literature around the climate effects (principally CO2 abatement) of sourcing biomass for bioenergy from forests managed according to sustainable forest management principles and practices.

The report highlights the dual impact managed forests contribute to climate change mitigation by providing material for forest products, including biomass that replace greenhouse gas (GHG)-intensive fossil fuels, and by storing carbon in forests and in long-lived forest products.

The role of biomass and bioenergy in decarbonising economies goes beyond just replacing fossil fuels. The addition of carbon capture and storage (CCS) to bioenergy to create bioenergy with carbon capture and storage (BECCS) enables renewable power generation while removing carbon from the atmosphere and carbon cycle permanently.

The negative emissions made possible by BECCS are now seen as a fundamental part of many scenarios to limit global warming to 1.5oC above pre-industrial levels.

BECCS and the path to net zero

The IPCC’s special report on limiting global warming to 1.5oC above pre-industrial levels, emphasises that even across a wide range of scenarios for energy systems, all share a substantial reliance on bioenergy – coupled with effective land-use that prevents it contributing to deforestation.

The second chapter of the report deals with pathways that can bring emissions down to zero by the mid-century. Bioenergy use is substantial in 1.5°C pathways with or without CCS due to its multiple roles in decarbonising both electricity generation and other industries that depend on fossil fuels.

However, it’s the negative emissions made possible by BECCS that make biomass  instrumental in multiple net zero scenarios. The IPCC report highlights BECCS alongside the associated afforestation and reforestation (AR), that comes with sustainable forest management, are key components in pathways that limit climate change to 1.5oC.

Graphic showing how BECCS removes carbon from the atmosphere. Click to view/download

There are two key factors that make BECCS and other forms of emissions removals so essential: The first is their ability to neutralise residual emissions from sources that are not reducing their emissions fast enough and those that are difficult or even impossible to fully decarbonise. Aviation and agriculture are two sectors vital to the global economy with hard-to-abate emissions. Negative emissions technologies can remove an equivalent amount of CO2 that these industries produce helping balance emissions and progressing economies towards net zero.

The second reason BECCS and other negative emissions technologies will be so important in the future is in the removal of historic CO2 emissions. What makes CO2 such an important GHG to reduce and remove is that it lasts much longer in the atmosphere than any other. To help reach the Paris Agreement’s goal of limiting temperature rises to below 1.5oC removing historic emissions from the atmosphere will be essential.

In the UK, the  CCC’s 2018 report ‘Biomass in a low-carbon economy’ also points to BECCS as both a crucial source of energy and emissions abatement.

It suggests that power generation from BECCS will increase from 3 TWh per year in 2035 to 45 TWh per year in 2050. It marks a sharp increase from the 19.5 TWh that biomass (without CCS) accounted for across 2020, according to Electric Insights data. It also suggests that BECCS could sequester 1.1 tonnes of CO2 for every tonne of biomass used, providing clear negative emissions.

However, the report makes clear that unlocking the potential of bioenergy and BECCS is only possible when biomass stocks are managed in a sustainable way that, as a minimum requirement, maintains the carbon stocks in plants and soils over time.

With increased attention paid to forest management and land use, there is a growing body of evidence that points to bioenergy as a win-win solution that can decarbonise power and economies, while supporting healthy forests that effectively sequester CO2.

How bioenergy ensures sustainable forests

Biomass used in electricity generation and other industries must come from sustainable sources to offer a renewable, climate beneficial [or low carbon] source of power.

UK legislation on biomass sourcing states that operators must maintain an adequate inventory of the trees in the area (including data on the growth of the trees and on the extraction of wood) to ensure that wood is extracted from the area at a rate that does not exceed its long-term capacity to produce wood. This is designed to ensure that areas where biomass is sourced from retain their productivity and ability to continue sequestering carbon.

Ensuring that forestland remains productive and protected from land-use changes, such as urban creep, where vegetated land is converted into urban, concreted spaces, depends on a healthy market for wood products. Industries such as construction and furniture offer higher prices for higher-quality wood. While low-quality, waste wood, as well as residues from forests and wood-industry by-products, can be bought and used to produce biomass pellets.

A report by Forest 2 Market examined the relationship between demand for wood and forests’ productivity and ability to sequester carbon in the US South, where Drax sources about two-thirds of its biomass.

The report found that increased demand for wood did not displace forests in the US South. Instead, it encouraged landowners to invest in productivity improvements that increased the amount of wood fibre and therefore carbon contained in the region’s forests.

A synthesis report, which examines a broad range of research papers,  published in Forest Ecology and Management in March of 2021, concluded from existing studies that claims of large-scale damage to biodiversity from woody biofuel in the South East US are not supported. The use of these forest residues as an energy source was also found to lead to net GHG greenhouse emissions savings compared to fossil fuels, according to Forest Research.

Importantly the research shows that climate risks are not exacerbated because of biomass sourcing; in fact, the opposite is true with annual wood growth in the US South increasing by 112% between 1953 and 2015.

Delivering a “win-win solution”

The European Commission’s JRC Science for Policy literature review and knowledge synthesis report ‘The use of woody biomass for energy production in the EU’ suggests  a win-win forest bioenergy pathway is possible, that can reduce greenhouse gas emissions in the short term, while at the same time not damaging, or even improving, the condition of forest ecosystems.

However, it also makes clear “lose-lose” situations is also a possible, in which forest ecosystems are damaged without providing carbon emission reductions in policy-relevant timeframes.

Win-win management practices must benefit climate change mitigation and have either a neutral or positive effect on biodiversity. A win-win future would see the afforestation of former arable land with diverse and naturally regenerated forests.

The report also warns of trade-offs between local biodiversity and mitigating carbon emissions, or vice versa. These must be carefully navigated to avoid creating a lose-lose scenario where biodiversity is damaged and natural forests are converted into plantations, while BECCS fails to deliver the necessary negative emissions.

In a future that will depend on science working in collaboration with industries to build a net zero future continued research is key to ensuring biomass can deliver the win-win solution of renewable electricity with negative emissions while supporting healthy forests.

Enviva Cottondale pellet plant catchment area analysis

18 August 2021

Sustainable bioenergy

The Enviva Cottondale pellet mill has a production capacity of 760,000 metric tonnes of wood pellets annually. Raw material used by the mill includes a combination of roundwood, chips, and secondary residuals (i.e., sawdust and shavings), with pine accounting for 80‐90% of total feedstock. In October 2018, Hurricane Michael passed through the centre of the Cottondale catchment area, causing significant damage to the forest resource with more than 500,000 hectares (ha) of forestland destroyed and an estimated loss of 42 million m3of timber (equivalent to around 4 times the UK annual production of roundwood).

This event has had an impact on the data trends for forest inventory, growth and harvesting removals – as harvesting levels were increased to salvage as much timber as possible before it became unusable due to decay. This can be clearly seen in many of the charts below. However, these forest areas have been restored and now continue to grow, allowing the catchment area to return to its pre-hurricane trends in the medium term.

Forest Area 

The catchment area around Enviva’s Cottondale pellet mill includes 4.3 million ha of land, based on the historical feedstock sourcing patterns of the mill. Timberland represents 68.7% (2.95 million ha) of the total land area in the Cottondale catchment area, this has increased slightly since 2000 from 67.8% and can be considered to have remained stable over this time period.  There are also around 300,000 ha of woodland (associated with agricultural land) and around 800,000 ha of cropland and pastureland.  Forestry is the dominant land use in this catchment area (Figure 1).

Figure 1: Land area by usage

Planted pine represents 33% of the timberland area, natural pine 20%, with 10% mixed stands and the remainder being hardwood forest of which 94% is naturally regenerated (Figure 2).  The breakdown of forest type and species composition has remained relatively stable and largely unchanged over the last 20 years, in contrast to other parts of the US South where some natural pine stands have been converted to planted pine. The pine and mixed forest areas are actively managed and produce the majority of the timber harvest in the catchment area. Despite the large area of hardwood forest, management and timber production is limited. Much of this area is classified as bottomland hardwood located alongside rivers, streams, and creeks and in streamside management zones (SMZs), which restricts active management. In addition, the proportion of this catchment area located in Florida contains a large area of swampland, which is largely composed of hardwoods and cannot be actively managed for timber production and is recognised as having important ecological value.

Figure 2: Breakdown of forest type

Volume and Growth

The overall trend of volume and growth in the Cottondale catchment area is of a maturing forest resource and an increasing accumulation of standing volume, particularly in the larger forest product classes (saw-timber and chip-n-saw). Figure 3 shows that total standing volume increased by 64 million m3 from 2000 to 2018, with the largest increases in the pine saw-timber and chip-n-saw categories. In 2018, the devastating impact of Hurricane Michael caused a substantial reduction in the standing volume across every product category with the total standing volume being reduced by 42 million m3. This event has had a significant impact on the forest resource and is a primary cause of recent data trends.

However, the overall long-term trend in the catchment area is of maturing forest and increasing inventory. This should continue in the long-term once the impact of the hurricane damage has been managed and replacement forest areas begin to mature.

Figure 3: Standing volume by product category

Pine pulpwood inventory increased steadily by around 8 million m3 from 2000 to 2013, reaching a peak of 49 million m3. This then declined slightly to 46 million m3 in 2018 due to the maturing age class of the forest and pulpwood forest growing into the larger size class of chip-n-saw and saw-timber forest (Figure 4), in addition to an increase in pulpwood demand as biomass markets became operational and ramped up production. Following the hurricane in 2018, the pine pulpwood inventory dropped by more than 10 million m3. 

Replanting and reforestation of damaged areas will ensure that future pine pulpwood production will increase again once these forests start to mature.

In the period from 2000 to 2018 pine sawtimber standing volume increased by 41.5 million m3 (78%) and chip-n-saw by 19.6 million m3 (73%), indicating a maturing age class and a growing forest resource. The 2018 hurricane caused a reduction in standing volume in both of these product categories of 11.6 and 8 million m3respectively (12% and 17% of the 2018 volume). However, the increasing trend is likely to continue once the forest area recovers.

Figure 4: Standing volume by product category

The growth drain ratio (GDR) is the comparison of average annual growth to removals (typically harvesting), where the growth exceeds removals the GDR will be in excess of 1 and this is considered sustainable, where removals exceed growth then the GDR will be less than 1 and this is not sustainable if maintained in the long-term – although in the short-term this can be a factor of large areas of mature forest with low growth rates and high rates of harvesting, short periods of high demand for a particular product or salvage harvesting after a natural disturbance. The GDR should be considered over a longer time period to ensure it reflects the long-term trend. In the period from 2003 to 2020 the combined GDR for pine products averaged 1.52 with a high of 1.84 and a low of 1.08 (Figure 5).

Figure 5: Growth to drain ratio by product category

The maturing forest resources can be clearly seen from the growth to removals data for each product category. Average tree sizes getting larger and more pulpwood class stands moving into the larger saw-timber and chip-n-saw categories. This trend can be seen by comparing the data values from 2003 and 2018 where saw-timber average annual growth increased by 90% (1.6 million m3), and removals by 41% (0.98 million m3).  Chip-n-saw growth increased by 73% (1.3 million m3) whilst removals increased by 160% (1.9 million m3). Pulpwood growth decreased by 7.5% (0.4 million m3) whilst removals increased by 63% (1.6 million m3).  Over this time period the total annual surplus of pine growth compared to removals averaged 3.7 million m3 per year (Figure 6).

Figure 6: Pine growth and removals by product category and year

Hardwood saw-timber and pulpwood removals declined by 20% and 40% respectively between 2000 and 2018, whilst growth increased by 23% for hardwood saw-timber and declined by 16% for hardwood pulpwood. The average annual hardwood surplus over this time period was 1.5 million m3 per year (Figure 7).

Figure 7: Hardwood growth and removals by product category and year

Despite a short-term imbalance in some product categories, the overall surplus of pine growth compared to removals has remained strong, with an average of 3.3 million m3 between 2000 and 2020, which includes the increased salvage harvesting in 2018 (Figure 8).

Figure 8: Cumulative annual surplus of growth compared to removals

Wood Prices

Stumpage price is the value paid to the forest owner for each category of product at the time of harvesting. The variation in prices in the Cottondale catchment area has been significant and shows some interesting trends. The higher value pine products (saw-timber and chip-n-saw) began with high stumpage values in 2000, as markets were strong for construction and furniture grade timber and supply limited at that stage due to the young age class and predominance of pulpwood stands at that time.  In 2008, following the global economic crisis and the crash in housing and construction markets, saw-timber prices declined substantially reaching a low of $23 per ton, a 47% decline from the 2000 price. This stumpage price has never recovered, despite an improvement in the economy and an increase in housing starts and demand for structural timber. The reason for the continued deflated saw-timber stumpage price is a substantial surplus of supply in this catchment area.  As the forest area has matured and more saw-timber grade stands are available, markets have been able to satisfy demand without an increase in price.

Pine pulpwood prices at Cottondale were lower than the US South-wide average in 2000 and remained relatively low until around 2013. A reduction in saw-timber production, and consequent reduction in mill residuals, due to the recession of 2008, led to a shortage of pulp mill feedstock and increased harvesting of pulpwood stands. This caused an increase in pine pulpwood stumpage values alongside an overall increase in demand as biomass and pellet markets began production around this time. The data shows a short-term spike in pine pulpwood stumpage prices in 2013-14, but this returned to a more normal trend as more saw-timber residues became available and pulpwood stumpage values have been around $10-11 per ton since 2015 (Figure 9).

Figure 9: Variation in stumpage value over time

Biomass demand 

Biomass demand in the Cottondale catchment area began in 2008 and has averaged around 800 thousand m3per year since that time with a high of just over 1 million m3 in 2013 to 2015 and a low of 200 thousand m3 in 2008. Other pulpwood markets have had an average annual demand of 3.97 million m3 between 2000 and 2020 with a high of 4.76 million m3 in 2018 and a low of 3.2 million m3 in 2009.  In 2020 the biomass market represented 16% of the total pulpwood demand in the Cottondale catchment area (Figure 10).

Figure 10: Total pulpwood demand

Forest Management

The average size of clear-cut harvesting sites from 2000 to 2020 has been 47 ha, ranging from 38 ha up to 56 ha. The average size of thinning sites has been 65 ha, ranging from 55 ha up to 76 ha. When isolating the period from 2000 to 2010 and 2011 to 2020, the averages and range remain very similar, suggesting that there has been no significant change in harvesting coupe size over this period.

Figure 11: Average size of harvesting sites

The impact of biomass and wood pellet demand on the key metrics in this catchment area are considered below. This is a summary of Hood Consulting’s view on the trends and impacts in the Cottondale catchment area.

Is there any evidence that bioenergy demand has caused the following:

Deforestation?

No. US Forest Service (USFS) data shows a 55,166-hectare (+1.9%) increase in the total area of timberland in the Enviva Cottondale catchment area since the Enviva Cottondale pellet mill commenced production in 2008. Furthermore, a strong positive relationship was identified between biomass demand and timberland area, suggesting that the increase in timberland area since 2008 can be linked, to a degree, to increased demand attributed to bioenergy.

A change in management practices (rotation lengths, thinnings, conversion from hardwood to pine)?

Inconclusive. Changes in management practices have occurred in the catchment area over the last two decades. However, the evidence is inconclusive as to whether increased demand attributed to bioenergy has caused or is responsible for these changes.

Clearcuts and thinnings are the two major types of harvests that occur in this region, both of which are long-standing, widely used methods of harvesting timber. TimberMart-South (TMS) data shows that thinnings accounted for 63% of total reported harvest area in the Cottondale market from 2005-2011 but only 39% of total harvest area reported from 2012-2020. Specifically, the decreased prevalence of thinning since 2012 can be linked to the strengthening of pine pulpwood markets and concurrent weakening of pine sawtimber markets beginning in the mid-2000s.

Prior to the bursting of the US housing bubble in 2006, timber management in this market had been driven to a large degree by pine sawtimber production. However, challenging market conditions saw pine sawtimber stumpages prices decline more than 40% from 2006-2011. At the same time, pine pulpwood markets started to strengthen, with pine pulpwood stumpage prices increasing more than 50% from 2006-2010. So, with sawtimber markets weakening and pulpwood markets strengthening, the data suggests that many landowners decided to alter their management approach (i.e. to take advantage of strong pulpwood markets) and focus on short pulpwood rotations that typically do not utilize thinnings.

Bioenergy has had an impact on this market by adding an average of roughly 680,000 metric tons of additional pine pulpwood demand to this catchment area annually since 2008. However, bioenergy has accounted for only 17% of total softwood pulpwood demand in this market since Enviva Cottondale’s startup. Ultimately, the shift in management approach that occurred in this market can be more closely linked to other factors, such as increased softwood pulpwood demand from non-bioenergy sources (i.e. pulp/paper) as well as the weakening of pine sawtimber markets.

Diversion from other markets?

No. Demand for softwood (pine) sawlogs increased an estimated 23% in the Cottondale catchment area from 2008-2020. Also, there is no evidence that increased demand from bioenergy has caused a diversion from other softwood pulpwood markets (i.e. pulp/paper), as softwood pulpwood demand not attributed to bioenergy has increased 25% since the Cottondale mill’s startup in 2008.

An unexpected or abnormal increase in wood prices?

Inconclusive. The startup of Enviva Cottondale added more than 900,000 metric tons of softwood pulpwood demand to the catchment area from 2008-2013, and this increase in demand coincided with a 28% increase in the delivered price of pine pulpwood (PPW) – the primary roundwood product consumed by the Enviva Cottondale mill. However, since 2013, delivered PPW prices have held flat, despite biomass-related softwood pulpwood demand falling to an average of roughly 635,000 tons per year since 2016, down more than 40% compared to 2013 peak levels. (Note the decrease in roundwood consumption was due to a higher utilization of secondary residuals). It’s also important to point out that the roughly 410,000-metric ton decrease in softwood biomass demand from 2013 to 2020 was offset by a roughly 455,000-metric ton increase in softwood pulpwood demand from other sources.

Statistical analysis did identify a positive relationship between softwood biomass demand and delivered PPW price. However, that relationship was found to be relatively weak. The relationship between delivered PPW price and softwood pulpwood demand from other sources was found to be much stronger, which was not unexpected to find given that softwood pulpwood demand not attributed to bioenergy has accounted for 83% of total softwood pulpwood demand in the catchment area since 2008.

Furthermore, there is some evidence linking the increase in pine sawmill chip prices to increased consumption of secondary pine residuals by Enviva Cottondale. Specifically, consumption of secondary pine residuals by Enviva Cottondale more than doubled from roughly 213,000 metric tons in 2012 to nearly 490,000 metric tons in 2016, and this increased consumption of pine residuals coincided with a nearly 20% increase in the price of pine sawmill chips. However, increased consumption of residuals by the bioenergy sector was only one of several contributing factors that can be linked to the increase in pine sawmill chip prices. Increased consumption of pine residuals by the pulp/paper industry also contributed to higher pine sawmill chip prices. In addition, there is a strong linkage between pine sawmill chip prices and softwood lumber production. Specifically, the increase in softwood lumber production that begun in the early-to-mid-2010s consequently resulted in the increased production of secondary residuals, and the increased availability of this lower-cost material led to greater competition and ultimately higher pine residual prices.

A reduction in growing stock timber?

No. From 2008 (the year Enviva Cottondale commenced production) up until Hurricane Michael struck in late-2018, total growing stock inventory increased an average of 1.8% per year (+19% total) in the Cottondale catchment area. Specifically, inventories of pine sawtimber and pine chip-n-saw increased 58% and 28%, respectively, while pine pulpwood (PPW) inventory decreased 4% over this same period.

However, note that the decrease in pine pulpwood inventory from 2008-2018 was not due to increased demand from bioenergy or increased harvesting above the sustainable yield capacity of the forest area, as annual growth of pine pulpwood exceeded annual removals every year throughout this period. Rather, this slight decrease in PPW inventory levels is more a reflection of the aging of the catchment area forest and the movement of stands classified as pulpwood to stands classified as chip-n-saw.

A reduction in the sequestration rate of carbon?

No. US Forest Service (USFS) data shows the average annual growth rate of total growing stock timber in the Cottondale catchment area decreased from 5.9% in 2008 to 5.2% in 2020, suggesting that the sequestration rate of carbon also declined slightly over this period. However, there is little evidence to suggest that increased demand attributed to bioenergy is responsible for this change.

The reduction in overall growth rate (and therefore reduction in the sequestration rate of carbon) is more a reflection of the aging of the catchment area forest. Specifically, growth rates decline as timber ages, and this is exactly what USFS data shows in the Cottondale catchment area, with the average age of growing stock timber increasing from less than 44 years of age in 2008 to nearly 46 years of age in 2020.

An increase in harvesting above the sustainable yield capacity of the forest area?

No. Growth-to-removals (G:R) ratios, which compare annual timber growth to annual timber removals, provides a measure of market demand relative to supply as well as a gauge of market sustainability. In 2020, the latest available, the G:R ratio for pine pulpwood (PPW), the predominant timber product utilized by the bioenergy sector, equaled 1.26 (recall that a value greater than 1.0 indicates sustainable harvest levels).

Note, however, that the PPW G:R ratio averaged 1.57 in the catchment area from 2013-2017 before falling to 1.20 in 2018 and averaging 1.27 since. This notable drop in 2018 was due to a nearly 35% increase in PPW removals (due to Hurricane Michael). It’s also important to note that while annual removals have moved back in line with pre-Michael levels since 2019, this lower PPW G:R ratio is likely reflective of the new norm (at least over the midterm). Hurricane Michael destroyed an estimated 22% of total pine pulpwood inventory in the Cottondale catchment area, and this loss in inventory will be reflected in reduced growth until the destroyed forests regenerate. However, in spite of this loss, adequate PPW inventory levels still remain and sustainable market conditions are expected to persist moving forward.

Timber growing stock inventory

Neutral. According to USFS data, inventories of pine pulpwood (PPW) decreased 25% in the catchment area from 2008-2020. However, this substantial decrease was due to Hurricane Michael, which destroyed nearly 520,000 hectares of catchment area timberland when it hit the Florida panhandle in late-2018. Prior to this event occurring, PPW inventory levels had held relatively steady, decreasing slightly but averaging 47.2 million m3 in the catchment area from 2008-2018. However, the destruction caused by Hurricane Michael resulted in the immediate loss of more than 10.3 million m3 of PPW inventory, or a 22% decrease compared to pre-hurricane levels.

Moreover, the slight decrease in PPW inventory levels that did occur from 2008-2018 was not due to increased demand from bioenergy. Typically, a reduction in inventory is linked to harvest levels above the sustainable yield capacity of the forest area, but in the Cottondale catchment area, annual growth of PPW exceeded annual removals every year throughout this period. Ultimately, the decrease in PPW inventory from 2008-2018 can be more closely linked to decreased pine sawtimber production beginning in the early to mid-2000s. Specifically, annual removals of pine sawtimber decreased 28% from 2003-2014, and the reduction in harvest levels over this period translated to a reduction in newly-re-established pine stands and ultimately the slight reduction in PPW inventory levels that occurred in the mid-to-late 2010s.

Timber growth rates

Neutral. Overall, timber growth rates declined slightly in the catchment area from 2008 (the year Enviva Cottondale commenced operations) through 2020. However, this decrease in timber growth rates was not due to increased demand attributed to bioenergy but rather to the aging of the catchment area forest. Specifically, USFS data shows the average age timber inventory in the Cottondale catchment area increased from an estimated 43.6 years of age in 2008 to 45.7 years of age in 2020.

Forest area

Positive. In the Enviva Cottondale catchment area, total forest area (i.e. timberland) increased more than 55,100 hectares (+1.9%) from 2008 through 2020, and this increase can be linked to several factors, including increases in softwood pulpwood demand (from both bioenergy and other sources) as well as conversion from farmland.

Specifically, the more than 55,100-hectare increase in catchment area timberland from 2008-2020 coincided with a 1.1-million metric ton increase in annual softwood pulpwood demand (roughly half of which was attributed to bioenergy). While statistical analysis identified moderately strong positive relationships between timberland area and both softwood biomass demand and non-bioenergy-related softwood pulpwood demand, a strong positive correlation was found between timberland and total softwood pulpwood demand – suggesting that the increases in timberland since 2008 can be attributed, in part, to the increase in total softwood pulpwood demand (from both bioenergy and other sources).

The more than 55,100-hectare increase timberland from 2008-2020 also coincided with a roughly 75,000-hectare decrease in farmland (i.e. cropland, woodland, and pastureland) over this period. Specifically, the catchment area experienced a roughly 31,800-hectare loss in cropland, 8,900-hectare loss in pastureland, and 34,300-hectare loss in woodland from 2008-2020. Furthermore, statistical analysis confirmed this inverse relationship, identifying a strong negative correlation between timberland and farmland in the Cottondale catchment area.

Wood prices

Negative / Positive. Total softwood pulpwood demand attributed to bioenergy in the Cottondale catchment area increased from zero tons in 2007 (the year prior to Enviva Cottondale’s startup) to over 1.0 million metric tons in 2013. Over this same period, the price of delivered pine pulpwood (PPW) – the predominant roundwood product utilized by Enviva Cottondale for wood pellet production – increased 42% (from $21.06 per ton in 2007 to $29.82 per ton in 2013).

However, the apparent link between increased softwood biomass demand and increased delivered PPW price is only loosely supported by statistical analysis, which identified a relatively weak positive relationship between these two variables. Furthermore, delivered PPW price has remained nearly unchanged in the catchment area since 2013, despite softwood biomass demand declining and averaging roughly 577,000 metric tons per year since 2016. (Note that the roughly 410,000-metric ton decrease in softwood biomass demand from 2013-2020 was offset by a roughly 455,000-metric ton increase in softwood pulpwood demand from other sources). Ultimately, the increase in delivered PPW prices in the catchment area can be linked to increased demand for softwood pulpwood from all sources, and roughly half of the 1.2-million metric ton increase in softwood pulpwood demand since 2007 can be attributed to bioenergy.

However, it’s also important to note that the increase in bioenergy-related wood demand has been a positive for forest landowners in the Enviva Cottondale catchment area. Not only has bioenergy provided an additional outlet for pulpwood in this market, but the increase in delivered PPW price resulting from increased softwood pulpwood demand from bioenergy has transferred through to landowners in the form of higher PPW stumpage prices. Specifically, over the six years prior to Enviva Cottondale’s startup, PPW stumpage price – the price paid to landowners – averaged roughly $7.40 per ton in the Cottondale catchment area. However, since 2010, PPW stumpage prices have averaged more than $11.15 per ton, representing a more than 50% increase compared to pre-mill startup levels.

Markets for solid wood products

Positive. In the Enviva Cottondale catchment area, demand for softwood sawlogs used to produce lumber and other solid wood products increased an estimated 23% from 2008-2020. This increase in softwood lumber production has consequentially resulted in an increase in sawmill residuals (i.e. chips, sawdust, and shavings) – by-products of the sawmilling process and materials utilized by Enviva Cottondale to produce wood pellets.

Specifically, softwood sawlog demand has increased more than 16% in the catchment area since 2014, and this increase in demand has coincided with a nearly 60% increase in pine residual purchases by Enviva Cottondale. (Note that pine residuals constituted 25% of total raw material purchases by Enviva Cottondale in 2014 but 41% of total raw material purchases in 2020). So, not only has Enviva Cottondale benefited from the greater availability of this sawmill by-product, but lumber producers have also benefited, as Enviva Cottondale has provided an additional outlet for these producers and their by-products.

Read the full report: Enviva Cottondale pellet plant catchment area analysis. 

This is part of a series of catchment area analyses around the forest biomass pellet plants supplying Drax Power Station with renewable fuel. Others in the series can be found here. 

What is bioenergy with carbon capture and storage (BECCS)?

18 May 2021

Carbon capture

What is bioenergy with carbon capture and storage (BECCS)? 

Bioenergy with carbon capture and storage (BECCS) is the process of capturing and permanently storing carbon dioxide (CO2) from biomass (organic matter) energy generation.

Why is BECCS important for decarbonisation? 

When sustainable bioenergy is paired with carbon capture and storage it becomes a source of negative emissions, as CO2 is permanently removed from the carbon cycle.

Experts believe that negative emissions technologies (NETs) are crucial to helping countries meet the long-term goals set out in the Paris Climate Agreement. As BECCS is the most scalable of these technologies this decade, it has a key role to play in combating climate change.

How is the bioenergy for BECCS generated?

Most bioenergy is produced by combusting biomass as a fuel in boilers or furnaces to produce high-pressure steam that drives electricity-generating turbines. Alternatively, bioenergy generation can use a wide range of organic materials, including crops specifically planted and grown for the purpose, as well as residues from agriculture, forestry and wood products industries. Energy-dense forms of biomass, such as compressed wood pellets, enable bioenergy to be generated on a much larger scale. Fuels like wood pellets can also be used as a substitute for coal in existing power stations.

How is the carbon captured?

BECCS uses a post-combustion carbon capture process, where solvents isolate CO2 from the flue gases produced when the biomass is combusted. The captured CO2 is pressurised and turned into a liquid-like substance so it can then be transported by pipeline.

How is the carbon stored?

Captured CO2 can be safely and permanently injected into naturally occurring porous rock formations, for example unused natural gas reservoirs, coal beds that can’t be mined, or saline aquifers (water permeable rocks saturated with salt water). This process is known as sequestration.

Over time, the sequestered CO2 may react with the minerals, locking it chemically into the surrounding rock through a process called mineral storage.

BECCS fast facts

Is BECCS sustainable?

 Bioenergy can be generated from a range of biomass sources ranging from agricultural by-products to forestry residues to organic municipal waste. During their lifetime plants absorb CO2 from the atmosphere, this balances out the CO2that is released when the biomass is combusted.

What’s crucial is that the biomass is sustainably sourced, be it from agriculture or forest waste. Responsibly managed sources of biomass are those which naturally regenerate or are replanted and regrown, where there’s a increase of carbon stored in the land and where the natural environment is protected from harm.

Biomass wood pellets used as bioenergy in the UK, for example, are only sustainable when the forests they are sourced from continue to grow. Sourcing decisions must be based on science and not adversely affect the long-term potential of forests to store and sequester carbon.

Biomass pellets can also create a sustainable market for forestry products, which serves to encourage reforestation and afforestation – leading to even more CO2 being absorbed from the atmosphere.

Go deeper:

  • The triple benefits for the environment and economy of deploying BECCS in the UK.
  • How BECCS can offer essential grid stability as the electricity system moves to low- and zero-carbon sources.
  • Producing biomass from sustainable forests is key to ensuring BECCS can deliver negative emissions.
  • 5 innovative projects where carbon capture is already underway around the world
  • 7 places on the path to negative emissions through BECCS

Evaluating regrowth post-harvest with accurate data and satellite imagery

13 May 2021

Sustainable bioenergy

  • Drax has been using effective post-harvest evaluations, which includes remote sensing technology and satellite imagery

  • Alongside sustainable forest management, monitoring can help support rapid regrowth after harvesting

  • Evidence shows healthy managed forests with no signs of deforestation or degradation

As part of Drax’s world-leading programme of demonstrating biomass sustainability, including ongoing work on catchment area analysis (CAA), responsible sourcing policy and healthy forest landscapes (HFL). We have also been trialling the use of high-resolution satellite imagery to monitor forest conditions on specific harvesting sites in the years after harvesting has taken place, in addition to the catchment area level monitoring of trends and data. Post-harvest evaluations (PHE) are an essential part of an ongoing sustainability monitoring process, ensuring that the future forest resource is protected and maintained and that landowners restore forests after harvesting to prevent deforestation or degradation.

The most effective form of PHE is for an experienced local forester to walk and survey the harvesting site to check that new trees are growing and that the health and quality of the young replacement forest is maintained.

Rapid regrowth

The images below show some of the sites surrounding Drax’s Amite Bioenergy pellet plant in Mississippi, with trees at various stages of regrowth in the years after harvesting.

A full site inspection can therefore enable a forester to determine whether the quantity and distribution of healthy trees is sufficient to make a productive forest, equivalent to the area that was harvested. It can also identify if there are any health problems, pest damage or management issues such as  weed growth or water-logging that should be resolved.

Typically, this will be the responsibility of the forest owner or their forest manager and is a regular part of ongoing forest management activity. This degree of survey and assessment is not practical or cost-effective where a third-party consumer of wood fibre purchases a small proportion (typically 20-25 tonnes per acre) of the low-grade fibre produced at a harvest as a one-off transaction for its wood pellet plant..  It is time consuming to walk every acre of restocked forest and it is not always possible to get an owner’s permission to access their land.

Forests from space

Therefore, an alternative methodology is required to make an assessment about the condition of forest lands that have been harvested to supply biomass, without the need to physically inspect each site.  One option is to use remote sensing and satellite imagery to view each harvested site in the years after biomass sourcing, this helps to monitor restocking and new tree growth.

Drax has been testing the remote sensing approach using Maxar’s commercial satellite imagery.  Maxar has four satellites on orbit that collect more than three million square kilometres of high-resolution imagery every day. Drax accesses this imagery through Maxar’s subscription service SecureWatch.

To test the viability of this methodology, Drax has been looking at harvesting sites in Mississippi that supplied biomass to the Amite Bioenergy pellet plant in 2015 and in 2017.  As part of the sustainability checks that are carried out prior to purchasing wood fibre, Drax collects information on each harvesting tract. This includes the location of the site, the type of harvest, the owner’s long-term management intentions and species and volume details.

This data can then be used at a later date to revisit the site and monitor the condition of the area. Third-party auditors, for instance Through Sustainable Biomass Program (SBP) certification, do visit harvesting sites, however this is typically during the year of harvest rather than after restocking. Maxar has historical imagery of this region from 2010, which is prior to any harvesting for wood pellets.  The image below shows a harvesting site near the pellet plant at Gloster, Mississippi, before any harvesting has taken place.

March 2010 (100m)

Satellite image © 2021 Maxar Technologies.

The image below shows the same site in 2017 immediately following harvesting.

December 2017 (100m)

Satellite image © 2021 Maxar Technologies.

If we look again at this same site three years after harvesting, we can see the rows of trees that have been planted and the quality of the regrowth. This series of images demonstrates that this harvested area has remained a forest, has not been subject to deforestation and that the regrowth appears to be healthy at this stage.

August 2020 (50m)

Satellite image © 2021 Maxar Technologies.

Another site in the Amite catchment area is shown below. The image shows a mature forest prior to harvesting, the site has been previously thinned as can be seen from the thinned rows that are evident in the imagery.

May 2010 (200m)

Satellite image © 2021 Maxar Technologies.

Looking at the same site in the year after harvesting, the clear cut area can be seen clearly. Some green vegetation cover can also be seen on the harvested area, but this is weed growth rather than replanted trees. Some areas of mature trees have been left at the time of harvesting, and are visible as a grey colour in the 2010 image. These are likely to be streamside management zones that have been left to maintain biodiversity and to protect water quality, with the grey winter colouring suggesting that they are hardwoods.

September 2018 (200m)

Satellite image © 2021 Maxar Technologies.

Three years after the harvest, in a zoomed in view from the previous image, clear rows of replanted trees can be seen in the imagery.  This demonstrates that the owner has successfully restocked the forest area and that the newly planted forest appears healthy and well established.

August 2020 (50m)

Satellite image © 2021 Maxar Technologies.

While examining different harvesting sites in satellite imagery, Drax noted that not every site had evidence of tree growth, particularly within the first three years after harvesting. Deliberate conversion of land to non-forest use, such as for conversion to pasture, agricultural crops or urban development, is likely to be evident fairly soon after harvesting.

Preparing for planting

Some forest owners like to leave a harvested site unplanted for a couple of years to allow ground vegetation and weed growth to establish, this can then be treated to ensure that trees can be planted and that the weed growth does not impede the establishment of the new forest, this process can mean that trees are not visible in satellite imagery for three to four years after harvesting.

The image below shows a site three years after harvesting with no evidence of tree growth.  Given that no conversion of land use is evident and that the site appears to be clear of weed growth, this is likely to be an example of where the owners have waited to clear the site of weeds prior to replanting.  This site can be monitored in future imagery from the Maxar satellites to ensure that forest regrowth does take place.

November 2020 (100m)

Satellite image © 2021 Maxar Technologies.

Drax will continue to use Maxar’s SecureWatch platform to monitor the regrowth of harvesting sites and will publish more detailed results and analysis when this process has been developed further.  The platform allows ongoing comparison of a site over time and could prove a more efficient method of analysis than ground survey.  In conjunction with the CAA and HFL work, PHE can add remote sensing as a valuable monitoring and evidence-gathering tool to demonstrate robust biomass sustainability standards and a positive environmental impact.

Go deeper: 

Discover the steps we take to ensure our wood pellet supply chain is better for our forests, our planet and our future here, how to plant more trees and better manage them, our responsible sourcing policy for biomass from sustainable forests and a guide to sustainable forest management of the Southern Working Forest.

The world’s leading sustainable biomass generation and supply business

Will Gardiner, Chief Executive Officer, Drax Group

13 April 2021

Opinion

Today we completed a transformational deal – our acquisition of Canadian biomass pellet producer Pinnacle Renewable Energy.

I’m very excited about this important acquisition and welcoming our new colleagues to the Drax family – together we will build on what we have already achieved, having become the biggest decarbonisation project in Europe and the UK’s largest single site renewable power generator as a result of us using sustainable biomass instead of coal.

The deal positions Drax as the world’s leading sustainable biomass generation and supply business – making us a truly international business, trading biomass from North America to Europe and Asia. It also advances our strategy to increase our self supply, reduces our biomass production costs and creates a long-term future for sustainable biomass – a renewable energy source that the UN’s IPCC says will be needed to achieve global climate targets.

It’s also an important milestone in Drax’s ambition to become a carbon negative company by 2030 and play an important role in tackling the global climate crisis with our pioneering negative emissions technology BECCS.

That’s because increasing our annual production capacity of sustainable biomass while also reducing costs helps pave the way for our plans to use bioenergy with carbon capture and storage (BECCS) at Drax.

Negative emissions from BECCS are vital to address the global climate emergency while also providing the renewable electricity needed for a net zero economy, supporting jobs and clean growth in a post-Covid recovery.

Inside a Pinnacle pellet mill

Inside a Pinnacle pellet mill

We already know Pinnacle well – it is one of our key suppliers and the company is a natural fit with Drax.

Our new colleagues have a wealth of operational and commercial expertise so I’m looking forward to seeing what we can achieve together.

We will benefit from Pinnacle’s scale, operational efficiency and low-cost fibre sourcing, that includes a high proportion of sawmill residues. In 2019, Pinnacle’s production cost was 20% lower than Drax’s.

Completing this deal will increase our annual production capacity to 4.9 million tonnes of sustainable biomass pellets at 17 plants in locations across Western Canada and the US South – up from 1.6Mt now.

It also expands our access to three major North American fibre baskets and four export facilities, giving us a large and geographically diversified asset base, which enhances our sourcing flexibility and security of supply.

This positions us well to take advantage of the global growth opportunities for sustainable biomass. The market for biomass wood pellets for renewable generation in Europe and Asia is expected to grow in the current decade, principally driven by demand in Asia.

Biomass wood pellet storage dome, Drax Power Station

Biomass wood pellet storage dome, Drax Power Station

We believe that with increasingly ambitious global decarbonisation targets, the need for negative emissions and improved understanding of the role that sustainably sourced biomass can play, will result in continued robust demand.

Pinnacle is already a key supplier of wood pellets to other markets with C$6.7 billion of long-term contracts with high quality Asian and European customers, including Drax, and a significant volume contracted beyond 2027.

Drax aims to leverage Pinnacle’s trading capability across its expanded portfolio. We believe that the enlarged supply chain will provide greater opportunities to optimise the supply of biomass from its own assets and third-party suppliers.

The transport and shipping requirements of the enlarged company will provide further opportunities to optimise delivery logistics, helping to reduce distance, time, carbon footprint and cost.

Train transporting biomass wood pellets arriving at Drax Power Station

Importantly – there will also be opportunities to share best practice and drive sustainability standards higher across the group.

We recognise that the forest landscape in British Columbia and Alberta is different to the commercially managed forests in the south eastern US where we currently operate.

In line with our world leading responsible sourcing policy, Drax will work closely with environmental groups, Indigenous First Nation communities and other stakeholders and invest to deliver good environmental, social and climate outcomes in Pinnacle’s sourcing areas.

We are determined to create a long-term future for sustainable biomass and deliver BECCS –  the negative emissions technology that will be needed around the world to meet global climate targets. The acquisition of Pinnacle takes us a big step forward in achieving our goals.

Read press release: Drax completes acquisition of Pinnacle Renewable Energy Inc.

 

The science behind measuring and analysing trees

12 March 2021

Sustainable bioenergy
Weyerhaeuser working forest in Amite catchment area

We have published independent Catchment Area Analysis (CAA) reports for around 68% of the total biomass wood pellet supply to Drax Power Station in 2019. Within that, 73% of the pellets were manufactured in the US South accounting for 49% of that year’s total supply quantity.

A key component of CAA analysis are measurements, data and calculations provided by the National Forest Inventory (NFI). Bespoke wood price data, mill production capacity, market trends and interviews with local experts complete the picture.

The NFI in each country or region can be quite different in its intensity and frequency of measurement and overall degree of accuracy. In this article we examine the Forest Inventory and Analysis (FIA) database produced by the US Department of Agriculture Forest Service (USDA FS).

FIA traces its origin back to the McSweeney – McNary Forest Research Act of 1928 and began the first inventory in 1930. Since that time, it has been in continuous operation with a stated mission to: make and keep current a comprehensive inventory and analysis of the present and prospective conditions of and requirements for the renewable resources of the forest and rangelands of the US.

The fundamental science behind measuring tree height and diameter to calculate growth and volume has not changed much over the decades. A girth tape is used to measure the diameter at breast height (DBH), which is a point on the tree stem 1.37m above the base of the tree or the root collar (the exact height can vary by country). The height of a standing tree is conventionally measured using a clinometer or hypsometer, which measures the angle from the top of the tree to a measured distance away from the base. This forms a triangle from which the tree height can be calculated.

Example of girth and height measurement in the US South

The combination of height and girth are then used to estimate total tree volume based on historical models for that particular species in that country or region. Many decades worth of data measurements and modelling have been used to develop complex equations to estimate volume for each species and circumstance. This calculation process needs to estimate the rate of taper of the stem, or the difference in diameter between the base and the top of the tree. This can be consistent within a single species, but it can depend on growth rates and planting density (for example closely stocked trees may grow taller and thinner but more openly planted trees tend to be shorter and wider). Whether the site has been thinned, how many times, and at what age, can impact the degree of taper in the stem. Through many years of research, measuring and modelling the Southern Research Station (SRS) FIA team has developed the following formula for under-bark volume calculation:

under-bark volume calculation

This is then modified according to the parameters shown below, depending on species and stem characteristics.

Example of volume

Example of volume

Once the volume has been calculated, the basic density (solid wood per cubic metre) and moisture content can be used to calculate wet and dry weight, fibre content and yield.

A comprehensive record of data

The US Forest Service has built up an extensive historical record of data points through years of physical measurements – from both sampling and cutting down individual sample trees to determine the actual dimensions and statistics to compare against the estimated values. Over time, forest scientists are able to build up reasonably accurate tables for each tree species that can be used to estimate growth and volume based on the DBH and estimated tree height.

In the UK we have a forester’s handbook known as The Blue Book which contains a vast quantity of modelled data to help a forester calculate volume and growth in a range of different forest types across the country. This data has been collected and modelled by the Forestry Commission’s Forest Research branch. In the US they have a similar system of data collection and modelling but on a bigger scale, given the much larger forest area and greater variety in tree species and site type.

How can you measure an entire forest?

The forestland area of the US South covers more than 100 million hectares (ha) in total which can present quite a challenge to measure, survey and accurately predict forest growth and health. The FIA does this through a network of sample plots randomly but sequentially distributed across the forestland in each State with undisclosed locations so as to avoid biased management. Field crews collect data on forest type, site attributes, tree species, tree size, and overall tree condition on accessible forest land.

Recently, the programme has involved a five-year rolling measurement system where 20% of the plots are measured in each State, on an annual basis. At the end of a five-year period all plots will have been measured and the process begins again. This process is overseen by a robust quality assurance system to maintain and ensure the quality and accuracy of the fieldwork.

Plots are distributed at a rate of 1 plot per 6,000 acres of land (or one per 2,400 ha). This degree of plot distribution is at an extremely course scale if attempting to understand the growth of an individual stand or forest area. For example, The Blue Book recommends using 8-12 plots (and top height measurements) for a relatively uniform stand of around 10 ha. This degree of accuracy would be required to calculate the volume of standing wood for sale. In comparison, the FIA data would be completely inaccurate if trying to monitor growth and trends at an individual forest level or even at county level. This sampling intensity and the scale of measurement are the most critical factors in assessing the validity of data and trends that are identified through the FIA and through the CAA analysis.

Quantifying the level of accuracy

The physical measurement procedure and volume modelling are well established processes with data and analysis collected over many decades to support the findings; this leads to a clearly quantifiable degree of error for each measured plot. The challenge comes when using plot data to estimate the values in the surrounding forest. At this scale, the level of accuracy will depend on the ratio of plots to total forest area and the total number of plots measured. The ratio of plots per ha in the US South is pre-determined, limited by the physical and financial constraints of actually measuring trees on the ground. However, the total number of plots used to evaluate trends can vary according to how large an area is assessed.

Fundamentally, if a single county is assessed then the total number of sample plots will be low and the potential for error will be high. If an entire State is assessed, then the number of plots is much larger (despite the same ratio of plots per ha) therefore the data and the trend is statistically much more accurate. Drax’s CAA analysis falls somewhere in between these two points, with each catchment area including multiple counties but not quite at the same scale as State level analysis. An example of the variation in error is shown in the table below.

Degree of error for key metrics in Drax’s CAA analysis

Degree of error for key metrics in Drax’s CAA analysis

The data showing total inventory (volume of wood growing in the forest) has been assessed for the Chesapeake catchment area in North Carolina and Virginia. When looking at each individual county, the data error calculation is +/- 46.5%, therefore not very accurate. If looking at State level, the data error is only +/- 2.7%. This degree of error is much more accurate and demonstrates more credible and reliable data due to the much larger number of plots available across the entire State. The Drax CAA analysis for inventory in the Chesapeake area is +/- 4.7% which is reasonably close to the State level accuracy due to the large number of countries that are included in the CAA analysis.

Since the catchment area boundary is defined by the pellet mill’s historical and future sourcing pattern, this can vary in size according to each mill’s procurement strategy and local market conditions. For example, the Amite BioEnergy pellet plant sources from a much smaller area close to the mill and therefore the catchment area includes fewer counties. This can lead to a higher degree of error than in the other CAA reports as the total number of plots used is smaller.

A long history of measurement and analysis

Despite this, the overall degree of error is still in single figures and can be considered reasonable in each CAA report by the standards of forest measurement and modelling, an error of under 10% is generally considered acceptable. Measuring standing trees that are still growing is not an exact science – it is an estimation. Trees cannot be accurately weighed or measured until they are cut down. Therefore, there will always be degree of error in estimated data. In the US South, the long history of measurement, analysis and data modelling and the relatively homogenous nature of the main commercial species (southern yellow pine), mean that the error is relatively uniform and predictable if a large sample area is considered.

The potential for remote sensing data collection and analysis to replace traditional field measurement is an interesting and developing field. At an individual forest or stand level, it is possible to carry out intensive measurement with Laser or Lidar, to calculate volume and growth. However, there is currently no reliable, accurate and cost-effective way to do this at a large-scale across several million hectares. This may be a possibility as the technology and data interpretation tools continue to develop and Drax is working closely with remote sensing specialists to trial and develop this process. Until then, we can rely on boots on the ground and traditional fieldwork for an accurate view of the forest trends across our supply chain.

This blog supports a series of catchment area analyses around the forest biomass pellet plants supplying Drax Power Station with renewable fuel. Read more.