Tag: technology

Transporting carbon – How to safely move CO2 from the atmosphere to permanent storage

15 October 2021

Carbon capture

Key points

Carbon capture usage and storage (CCUS) offers a unique opportunity to capture and store the UK’s emissions and help the country reach its climate goals.
Carbon dioxide (CO₂) can be stored in geological reservoirs under the North Sea, but getting it from source to storage will need a large and safe CO₂ transportation network.
The UK already has a long history and extensive infrastructure for transporting gas across the country for heating, cooking and power generation.
This provides a foundation of knowledge and experience on which to build a network to transport CO₂.

Across the length of the UK is an underground network similar to the trainlines and roadways that crisscross the country above ground. These pipes aren’t carrying water or broadband, but gas. Natural gas is a cornerstone of the UK’s energy, powering our heating, cooking and electricity generation. But like the country’s energy network, the need to reduce emissions and meet the UK’s target of net zero emissions by 2050 is set to change this.

Today, this network of pipes takes fossil fuels from underground formations deep beneath the North Sea bed and distributes it around the UK to be burned – producing emissions. A similar system of subterranean pipelines could soon be used to transport captured emissions, such as CO₂, away from industrial clusters around factories and power stations, locking them away underground, permanently and safely.

Conveyer system at Drax Power Station transporting sustainable wood pellets

The rise of CCUS technology is the driving force behind CO₂ transportation. The process captures CO₂from emissions sources and transports it to sites such as deep natural storage enclaves far below the seabed.

Bioenergy with carbon capture and storage (BECCS) takes this a step further. BECCS uses sustainable biomass to generate renewable electricity. This biomass comes from sources, such as forest residues or agricultural waste products, which remove CO₂from the atmosphere as they grow. Atmospheric CO₂released in the combustion of the biomass is then captured, transported and stored at sites such as deep geological formations.

Across the whole BECCS process, CO₂ has gone from the atmosphere to being permanently trapped away, reducing the overall amount of CO₂ in the atmosphere and delivering what’s known as negative emissions.

BECCS is a crucial technology for reaching net zero emissions by 2050, but how can we ensure the CO₂is safely transported from the emissions source to storage sites?

Moving gases around safely

Moving gases of any kind through pipelines is all about pressure. Gases always travel from areas of high pressure to areas of low pressure. By compressing gas to a high pressure, it allows it to flow to other locations. Compressor stations along a gas pipeline help to maintain right the pressure, while metering stations check pressure levels and look out for leaks.

The greater the pressure difference between two points, the faster gases will flow. In the case of CO₂, high absolute pressures also cause it to become what’s known as a supercritical fluid. This means it has the density of a liquid but the viscosity of a gas, properties that make it easier to transport through long pipelines.

Since 1967 when North Sea natural gas first arrived in the UK, our natural gas transmission network has expanded considerably, and is today made up of almost 290,000 km of pipelines that run the length of the country. Along with that physical footprint is an extensive knowledge pool and a set of well-enforced regulations monitoring their operation.

While moving gas through pipelines across the country is by no means new, the idea of CO₂ transportation through pipelines is. But it’s not unprecedented, as it has been carried out since the 1980s at scale across North America. In contrast to BECCS, which would transport CO₂ to remove and permanently store emissions, most of the CO₂ transport in action today is used in oil enhanced recovery – a means of ejecting more fossil fuels from depleted oil wells. However, the principle of moving CO₂ safely over long distances remains relevant – there are already 2,500 km of pipelines in the western USA, transporting as much as 50 million tonnes of CO₂ a year.

“People might worry when there is something new moving around in the country, but the science community doesn’t have sleepless nights about CO₂ pipelines,” says Dr Hannah Chalmers, from the University of Edinburgh. “It wouldn’t explode, like natural gas might, that’s just not how the molecule works. If it’s properly installed and regulated, there’s no reason to be concerned.”

CO₂ is not the same as the methane-based natural gas that people use every day. For one, it is a much more stable, inert molecule, meaning it does not react with other molecules, and it doesn’t fuel explosions in the same way natural gas would.

CO₂ has long been understood and there is a growing body of research around transporting and storing it in a safe efficient way that can make CCUS and BECCS a catalyst in reducing the UK’s emissions and future-proofing its economy.

Working with CO₂across the UK

Working with CO₂ while it is in a supercritical state mean it’s not just easier to move around pipes. In this state CO₂ can also be loaded onto ships in very large quantities, as well as injected into rock formations that once trapped oil and gas, or salt-dense water reserves.

Decades of extracting fossil fuels from the North Sea means it is extensively mapped and the rock formations well understood. The expansive layers of porous sandstone that lie beneath offer the UK an estimated 70 billion tonnes of potential CO₂ storage space – something a number of industrial clusters on the UK’s east coast are exploring as part of their plans to decarbonise.

Source: CCS Image Library, Global CCS Institute [Click to view/download]

Drax is already running a pilot BECCS project at its power station in North Yorkshire. As part of the Zero Carbon Humber partnership and wider East Coast Cluster, Drax is involved in the development of large scale carbon storage capabilities in the North Sea that can serve the Humber and Teesside industrial clusters. As Drax moves towards its goal of becoming carbon negative by 2030, transporting CO₂ safely at scale is a key focus.

“Much of the research and engineering has already been done around the infrastructure side of the project,” explains Richard Gwilliam, Head of Cluster Development at Drax. “Transporting and storing CO2 captured by the BECCS projects is well understood thanks to extensive engineering investigations already completed both onshore and offshore in the Yorkshire region.”

This also includes research and development into pipes of different materials, carrying CO₂ at different pressures and temperatures, as well as fracture and safety testing.

The potential for the UK to build on this foundation and progress towards net zero is considerable. However, for it to fully manifest it will need commitment at a national level to building the additional infrastructure required. The results of such a commitment could be far reaching.

In the Humber alone, 20% of economic value comes from energy and emissions-intensive industries, and as many as 360,000 jobs are supported by industries like refining, petrochemicals, manufacturing and power generation. Putting in place the technology and infrastructure to capture, transport and store emissions will protect those industries while helping the UK reach its climate goals.

It’s just a matter of putting the pipes in place.

Go deeper: How do you store CO₂ and what happens to it when you do?

What is LNG and how is it cutting global shipping emissions?

5 July 2019

Sustainable business

Oil tanker, Gas tanker operation at oil and gas terminal.

Shipping is widely considered the most efficient form of cargo transport. As a result, it’s the transportation of choice for around 90% of world trade. But even as the most efficient, it still accounts for roughly 3% of global carbon dioxide (CO₂) emissions.

This may not sound like much, but it amounts to 1 billion tonnes of CO₂and other greenhouse gases per year – more than the UK’s total emissions output. In fact, if shipping were a country, it would be the sixth largest producer of greenhouse gas (GHG) emissions. And unless there are drastic changes, emissions related to shipping could increase from between 50% and 250% by 2050.

As well as emitting GHGs that directly contribute towards the climate emergency, big ships powered by fossil fuels such as bunker fuel (also known as heavy fuel oil) release other emissions. These include two that can have indirect impacts – sulphur dioxide (SO₂) and nitrogen oxides (NOx). Both impact air quality and can have human health and environmental impacts.

As a result, the International Maritime Organization (IMO) is introducing measures that will actively look to force shipping companies to reduce their emissions. In January 2020 it will bring in new rules that dictate all vessels will need to use fuels with a sulphur content of below 0.5%.

One approach ship owners are taking to meet these targets is to fit ‘scrubbers’– devices which wash exhausts with seawater, turning the sulphur oxides emitted from burning fossil fuel oils into harmless calcium sulphate. But these will only tackle the sulphur problem, and still mean that ships emit CO₂.

Another approach is switching to cleaner energy alternatives such as biofuels, batteries or even sails, but the most promising of these based on existing technology is liquefied natural gas, or LNG.

What is LNG?

In its liquid form, natural gas can be used as a fuel to power ships, replacing heavy fuel oil, which is more typically used, emissions-heavy and cheaper. But first it needs to be turned into a liquid.

To do this, raw natural gas is purified to separate out all impurities and liquids. This leaves a mixture of mostly methane and some ethane, which is passed through giant refrigerators that cool it to -162^oC, in turn shrinking its volume by 600 times.

The end product is a colourless, transparent, non-toxic liquid that’s much easier to store and transport, and can be used to power specially constructed LNG-ready ships, or by ships retrofitted to run on LNG. As well as being versatile, it has the potential to reduce sulphur oxides and nitrogen oxides by 90 to 95%, while emitting 10 to 20% less CO₂than heavier fuel alternatives.

The cost of operating a vessel on LNG is around half that of ultra-low sulphur marine diesel (an alternative fuel option for ships aiming to lower their sulphur output), and it’s also future-proofed in a way that other low-sulphur options are not. As emissions standards become stricter in the coming years, vessels using natural gas would still fall below any threshold.

The industry is starting to take notice. Last year 78 vessels were fitted to run on LNG, the highest annual number to date.

One company that has already embraced the switch to LNG is Estonia’s Graanul Invest. Europe’s largest wood pellet producer and a supplier to Drax Power Station, Graanul is preparing to introduce custom-built vessels that run on LNG by 2020.

The new ships will have the capacity to transport around 9,000 tonnes of compressed wood pellets and Graanul estimates that switching to LNG has the potential to lower its CO₂emissions by 25%, to cut NOx emissions by 85%, and to almost completely eliminate SO₂and particulate matter pollution.

Is LNG shipping’s only viable option?

LNG might be leading the charge towards cleaner shipping, but it’s not the only solution on the table. Another potential is using advanced sail technology to harness wind, which helps power large cargo ships. More than just an innovative way to upscale a centuries-old method of navigating the seas, it is one that could potentially be retrofitted to cargo ships and significantly reduce emissions.

Drax is currently taking part in a study with the Smart Green Shipping Alliance, Danish dry bulk cargo transporter Ultrabulk and Humphreys Yacht Design, to assess the possibility of retrofitting innovative sail technology onto one of its ships for importing biomass.

: What a Pamamax ship carrying wood pellets may look like when retrofitted with sails

: Artist’s impression of a possible design for a wood pellet carrying sailing ship

Manufacturers are also looking at battery power as a route to lowering emissions. Last year, boats using battery-fitted technology similar to that used by plug-in cars were developed for use in Norway, Belgium and the Netherlands, while Dutch company Port-Liner are currently building two giant all-electric barges – dubbed ‘Tesla ships’ – that will be powered by battery packs and can carry up to 280 containers.

Then there are projects exploring the use of ammonia (which can be produced from air and water using renewable electricity), and hydrogen fuel cell technology. In short, there are many options on the table, but few that can be implemented quickly, and at scale – two things which are needed by the industry. Judged by these criteria, LNG remains the frontrunner.

There are currently just 125 ships worldwide using LNG, but these numbers are expected to increase by between 400 and 600 by 2020. Given that the world fleet boasts more than 60,000 commercial ships, this remains a drop in the ocean, but with the right support it could be the start of a large scale move towards cleaner waterways.

What is a fuel cell and how will they help power the future?

27 June 2019

Carbon capture

How do you get a drink in space? That was one of the challenges for NASA in the 1960s and 70s when its Gemini and Apollo programmes were first preparing to take humans into space.

The answer, it turned out, surprisingly lay in the electricity source of the capsules’ control modules. Primitive by today’s standard, these panels were powered by what are known as fuel cells, which combined hydrogen and oxygen to generate electricity. The by-product of this reaction is heat but also water – pure enough for astronauts to drink.

Fuel cells offered NASA a much better option than the clunky batteries and inefficient solar arrays of the 1960s, and today they still remain on the forefront of energy technology, presenting the opportunity to clean up roads, power buildings and even help to reduce and carbon dioxide (CO₂) emissions from power stations.

Power through reaction

At its most basic, a fuel cell is a device that uses a fuel source to generate electricity through a series of chemical reactions.

All fuel cells consist of three segments, two catalytic electrodes – a negatively charged anode on one side and a positively charged cathode on the other, and an electrolyte separating them. In a simple fuel cell, hydrogen, the most abundant element in the universe, is pumped to one electrode and oxygen to the other. Two different reactions then occur at the interfaces between the segments which generates electricity and water.

What allows this reaction to generate electricity is the electrolyte, which selectively transports charged particles from one electrode to the other. These charged molecules link the two reactions at the cathode and anode together and allow the overall reaction to occur. When the chemicals fed into the cell react at the electrodes, it creates an electrical current that can be harnessed as a power source.

Many different kinds of chemicals can be used in a fuel cell, such as natural gas or propane instead of hydrogen. A fuel cell is usually named based on the electrolyte used. Different electrolytes selectively transport different molecules across. The catalysts at either side are specialised to ensure that the correct reactions can occur at a fast enough rate.

For the Apollo missions, for example, NASA used alkaline fuel cells with potassium hydroxide electrolytes, but other types such as phosphoric acids, molten carbonates, or even solid ceramic electrolytes also exist.

The by-products to come out of a fuel cell all depend on what goes into it, however, their ability to generate electricity while creating few emissions, means they could have a key role to play in decarbonisation.

Fuel cells as a battery alternative

Fuel cells, like batteries, can store potential energy (in the form of chemicals), and then quickly produce an electrical current when needed. Their key difference, however, is that while batteries will eventually run out of power and need to be recharged, fuel cells will continue to function and produce electricity so long as there is fuel being fed in.

One of the most promising uses for fuel cells as an alternative to batteries is in electric vehicles.

Rachel Grima, a Research and Innovation Engineer at Drax, explains:

“Because it’s so light, hydrogen has a lot of potential when it comes to larger vehicles, like trucks and boats. Whereas battery-powered trucks are more difficult to design because they’re so heavy.”

These vehicles can pull in oxygen from the surrounding air to react with the stored hydrogen, producing only heat and water vapour as waste products. Which – coupled with an expanding network of hydrogen fuelling stations around the UK, Europe and US – makes them a transport fuel with a potentially big future.

Fuel cells, in conjunction with electrolysers, can also operate as large-scale storage option. Electrolysers operate in reverse to fuel cells, using excess electricity from the grid to produce hydrogen from water and storing it until it’s needed. When there is demand for electricity, the hydrogen is released and electricity generation begins in the fuel cell.

A project on the islands of Orkney is using the excess electricity generated by local, community-owned wind turbines to power a electrolyser and store hydrogen, that can be transported to fuel cells around the archipelago.

Fuel cells’ ability to take chemicals and generate electricity is also leading to experiments at Drax for one of the most important areas in energy today: carbon capture.

Turning CO₂to power

Drax is already piloting bioenergy carbon capture and storage technologies, but fuel cells offer the unique ability to capture and use carbon while also adding another form of electricity generation to Drax Power Station.

“We’re looking at using a molten carbonate fuel cell that operates on natural gas, oxygen and CO₂,” says Grima. “It’s basic chemistry that we can exploit to do carbon capture.”

The molten carbonate, a 600 degrees Celsius liquid made up of either lithium potassium or lithiumsodium carbonate sits in a ceramic matrix and functions as the electrolyte in the fuel cell. Natural gas and steam enter on one side and pass through a reformer that converts them into hydrogen and CO₂.

On the other side, flue gas – the emissions (including biogenic CO₂) which normally enter the atmosphere from Drax’s biomass units – is captured and fed into the cell alongside air from the atmosphere. The CO₂and oxygen (O₂) pass over the electrode where they form carbonate (CO₃^2-) which is transported across the electrolyte to then react with the hydrogen (H₂), creating an electrical charge.

“It’s like combining an open cycle gas turbine (OCGT) with carbon capture,” says Grima. “It has the electrical efficiency of an OCGT. But the difference is it captures CO₂from our biomass units as well as its own CO₂.”

Along with capturing and using CO₂, the fuel cell also reduces nitrogen oxides (NOx) emissions from the flue gas, some of which are destroyed when the O₂and CO₂react at the electrode.

From the side of the cell where flue gas enters a CO₂-depleted gas is released. On the other side of the cell the by-products are water and CO₂.

During a government-supported front end engineering and design (FEED) study starting this spring, this CO₂will also be captured, then fed through a pipeline running from Drax Power Station into the greenhouse of a nearby salad grower. Here it will act to accelerate the growth of tomatoes.

The partnership between Drax, FuelCell Energy, P3P Partners and the Department of Business, Energy and Industrial Strategy could provide an additional opportunity for the UK’s biggest renewable power generator to deploy bioenergy carbon capture usage and storage (BECCUS) at scale in the mid 2020s.

From powering space ships in the 70s to offering greenhouse-gas free transport, fuel cells continue to advance. As low-carbon electricity sources become more important they’re set to play a bigger role yet.

Learn more about carbon capture, usage and storage in our series:

Planting, sinking, extracting – some of the ways to absorb carbon from the atmosphere
From capture methods to storage and use across three continents, these companies are showing promising results for CCUS
Why experts think bioenergy with carbon capture and storage will be an essential part of the energy system
The science of safely and permanently putting carbon in the ground
The numbers must add up to enable negative emissions in a zero carbon future, says Drax Group CEO Will Gardiner.
The power industry is leading the charge in carbon capture and storage but where else could the technology make a difference to global emissions?
A roadmap for the world’s first zero carbon industrial cluster: protecting and creating jobs, fighting climate change, competing on the world stage
Can we tackle two global challenges with one solution: turning captured carbon into fish food?
How algae, paper and cement could all have a role in a future of negative emissions
How the UK can achieve net zero
Transforming emissions from pollutants to products
Drax CEO addresses Powering Past Coal Alliance event in Madrid, unveiling our ambition to play a major role in fighting the climate crisis by becoming the world’s first carbon negative company

4 of the most exciting emerging technologies in electricity generation

6 July 2017

Power generation

Since the dawn of the industrial age, the world has been powered by a relatively small set of technologies. The 20^th century was the age of coal, but this side of 2000, that’s changed.

The need to curb emissions and the rise of renewables, from wind to solar to biomass, has significantly changed how we fuel our power generation.

Today, some of the world’s most interesting and exciting emerging technologies are those designed to generate electricity.

Microbial fuel cells – harnessing the power of bacteria

Bacteria are all around us. Some are harmful, some are beneficial, but all of them ‘breathe’. When they breathe oxidation occurs, which is when something combines with oxygen at a chemical level, and when bacteria do this, electrons are released.

By connecting breathing microbes to a cathode and an anode (the positive and negative rods of a battery), the flow of these released electrons can be harnessed to generate power. This is what’s known as a microbial fuel cell (MFC). MFCs are used largely to generate electricity from waste water, but are expanding into more exotic uses, like powering miniature aquatic robots.

New developments are constantly expanding the power and applications of MFCs. Researchers at Binghamton University, New York found that combining phototropic (light-consuming) and heterotrophic (matter-consuming) bacteria in microbial fuel reactions generates currents 70 times more powerful than in conventional setups.

Solar – a new dawn

Solar power may not be a new technology, but where it’s going is.

One of the most promising developments in the space is solar voltaic glass, which has the properties of a sheet of window glass but can also generate solar power.

Rather than collecting photons like normal solar does (and which transparent materials by definition can’t do) photovoltaic glass uses salts to absorb energy from non-visible wavelengths and deflects these to conventional solar cells embedded at the edge of each panel.

Or there’s solar PV paint, which contains tiny light sensitive particles coated with conductive materials. When layered over electrodes you’ve got a spray-on power generator.

Betavoltaics – nothing wasted from nuclear waste

Nuclear material is constantly decaying and in the process emits radioactive particles. This is why extremely radioactive material is so dangerous and why properly storing nuclear waste is so important and so expensive. But this waste can actually be put to good use. Betavoltaic devices use the waste particles produced by low-level radioactive materials to capture electrons and generate electricity.

The output from these devices can be fairly low and decreases over long periods of time, but because of the consistent output of nuclear decay they can be extremely long-lasting. For example, one betavoltaic battery could provide one watt of power continuously for 30 years.

And while they aren’t currently fit to work on a large scale, their longevity (and very compact size) make them ideal power sources for devices such as sensors installed on equipment that needs to be operational for long periods.

Tidal power – changing tides

A more predictable power source than intermittent renewables like wind and solar, tidal power isn’t new, however its growth and development has typically been restrained by high costs and limited availability. That’s changing. Last year saw the launch of the first of 269 1.5 MW (megawatt) underwater turbines, part of world’s first large scale tidal energy farm in Scotland.

Around the world there are existing tidal power stations – such as the Sihwa Lake Tidal Power Station in South Korea, which has a capacity of 254MW – but the MeyGen array in Scotland will be able to take the potential of the technology further. It’s hoped that when fully operational it will generate 398MW, or enough to power 175,000 homes.

We might not know exactly how the electricity of tomorrow will be generated, but it’s likely some or all of these technologies will play a part. What is clear is that our energy is changing.

This is how you unload a wood chip truck

30 June 2017

Sustainable bioenergy

A truck arrives at an industrial facility deep in the expanding forestland of the south-eastern USA. It passes through a set of gates, over a massive scale, then onto a metal platform.

The driver steps out and pushes a button on a nearby console. Slowly, the platform beneath the truck tilts and rises. As it does, the truck’s cargo empties into a large container behind it. Two minutes later it’s empty.

This is how you unload a wood fuel truck at Drax Biomass’ compressed wood pellet plants in Louisiana and Mississippi.

What is a tipper?

“Some people call them truck dumpers, but it depends on who you talk to,” says Jim Stemple, Senior Director of Procurement at Drax Biomass. “We just call it the tipper.” Regardless of what it’s called, what the tipper does is easy to explain: it lifts trucks and uses the power of gravity to empty them quickly and efficiently.

The sight of a truck being lifted into the air might be a rare one across the Atlantic, however at industrial facilities in the United States it’s more common. “Tippers are used to unload trucks carrying cargo such as corn, grain, and gravel,” Stemple explains. “Basically anything that can be unloaded just by tipping.”

Both of Drax Biomass’ two operational pellet facilities (a third is currently idle while being upgraded) use tippers to unload the daily deliveries of bark – known in the forestry industry as hog fuel, which is used to heat the plants’ wood chip dryers – sawdust and raw wood chips, which are used to make the compressed wood pellets.

How does it work?

The tipper uses hydraulic pistons to lift the truck platform at one end while the truck itself rests against a reinforced barrier at the other. To ensure safety, each vehicle must be reinforced at the very end (where the load is emptying from) so they can hold the weight of the truck above it as it tips.

Each tipper can lift up to 60 tonnes and can accommodate vehicles over 50 feet long. Once tipped far enough (each platform tips to a roughly 60-degree angle), the renewable fuel begins to unload and a diverter guides it to one of two places depending on what it will be used for.

“One way takes it to the chip and sawdust piles – which then goes through the pelleting process of the hammer mills, the dryer and the pellet mill,” says Stemple. “The other way takes it to the fuel pile, which goes to the furnace.”

The furnace heats the dryer which ensures wood chips have a moisture level between 11.5% and 12% before they go through the pelleting process.

“If everything goes right you can tip four to five trucks an hour,” says Stemple. From full and tipping to empty and exiting takes only a few minutes before the trucks are on the road to pick up another load.

Efficiency benefits

Using the power of gravity to unload a truck might seem a rudimentary approach, but it’s also an efficient one. Firstly, there’s the speed it allows. Multiple trucks can arrive and unload every hour. And because cargo is delivered straight into the system, there’s no time lost between unloading the wood from truck to container to system.

Secondly, for the truck owners, the benefits are they don’t need to carry out costly hydraulic maintenance on their trucks. Instead, it’s just the tipper – one piece of equipment – which is maintained to keep operations on track.