Tag: renewable energy

Supporting a circular economy in the forests

Alan Knight, Group Director of Sustainability

16 June 2022

Opinion

Every year in British Columbia, millions of tonnes of waste wood – known in the industry as slash – is burned by the side of the road.

Land managers are required by law to dispose of this waste wood – that includes leftover tree limbs and tops, and wood that is rotten, diseased and already fire damaged – to reduce the risks of wildfires and the spread of disease and pests.

The smoke from these fires is choking surrounding communities – sometimes “smoking out entire valleys,” air quality meteorologist from BC’s Environment Ministry Trina Orchard recently told iNFOnews.ca.

It also impacts the broader environment, releasing some 3 million tonnes of CO2 a year into the atmosphere, according to some early estimates.

Slash pile in British Columbia

Landfilling this waste material from logging operations isn’t an option as it would emit methane – a greenhouse gas that is about 25 times more potent than CO2. So you can see why it ends up being burned.

In its Modernizing Forest Policy in BC, the government has already identified its intention to phase out the burning of this waste wood left over after harvesting operations and is working with suppliers and other companies to encourage the use of this fibre.

This is a very positive move as this material must come out of the forests to reduce the fuel load that can help wildfires grow and spread to the point where they can’t be controlled, let alone be extinguished.

The wildfire risk is real and growing. Each year more forests and land are destroyed by wildfire, impacting communities, nature, wildlife and the environment.

In the past two decades, wildfires burned two and a half times more land in BC than in the previous 50-year period. According to very early estimates, emissions from last year’s wildfires in the province released around 150 million tonnes of CO2 – equivalent to around 30 million cars on the road for a year.

Alan Knight at the log yard for Lavington Pellet Mill in British Columbia

During my recent trip to British Columbia in Canada, First Nations, foresters, academics, scientists and government officials all talked about the burning piles of waste wood left over after logging operations.

Rather than burning it, it would be far better, they say, to use more of this potential resource as a feedstock for pellets that can be used to generate renewable energy, while supporting local jobs across the forestry sector and helping bolster the resilience of Canada’s forests against wildfire.

I like this approach because it brings pragmatism and common sense to the debate over Canada’s forests from the very people who know the most about the landscape around them.

Burning it at the roadside is a waste of a resource that could be put to much better use in generating renewable electricity, displacing fossil fuels, and it highlights the positive role the bioenergy industry can play in enhancing the forests and supporting communities.

Drax is already using some of this waste wood – which I saw in the log yard for our Lavington Pellet mill in British Columbia. This waste wood comprises around 20% of our feedstock. The remaining 80% comes from sawmill residues like sawdust, chips and shavings.

Waste wood for pellets at Lavington Pellet Mill log yard

It’s clear to me that using this waste material that has little other use or market value to make our pellets is an invaluable opportunity to deliver real benefits for communities, jobs and the environment while supporting a sustainable circular economy in the forestry sector.

What is pumped storage hydro?

22 June 2021

Power generation

What is pumped storage hydro?

Pumped storage hydro (PSH) is a large-scale method of storing energy that can be converted into hydroelectric power. The long-duration storage technology has been used for more than half a century to balance demand on Great Britain’s electricity grid and accounts for more than 99% of bulk energy storage capacity worldwide.

How does it work?

The principle is simple. Pumped storage facilities have two water reservoirs at different elevations on a steep slope. When there is excess power on the grid and demand for electricity is low, the power is used to pump water from the lower to the upper reservoir using reversible turbines. When demand is high, the water is released downhill into the lower reservoir, driving the turbines the other direction to generate electricity.

Pumped storage hydro plants can also provide ancillary services to help balance the power system, such as inertia from spinning turbines, which ensures the system runs at the right frequency and reduces the risk of power cuts.

Why is pumped storage hydro important for energy transition?

Governments around the world are shifting from fossil fuels to renewable energy sources to meet their climate goals. But critically important power technologies such as wind and solar pose challenges for power grid operators.

Being weather-dependent, the supply from these renewables is intermittent. For example, wind farms accounted for almost a quarter of the UK’s total electricity generation in 2020, but on some days, less than 10% of the country’s electricity needs were met by wind. Changing weather patterns and extreme weather events with prolonged periods of little wind or reduced daylight are a further the threat to grid stability.

When output from renewables falls, grid operators mostly turn to gas-fired power stations to plug the gap. But relying on fossil fuels such as natural gas in the long term to balance the grid will compromise efforts to reach net zero emissions by 2050.

Pumped storage hydro facilities act as vast ‘water batteries’. They are a flexible way of storing excess energy generated by renewables, cost-effectively and at scale.

How can pumped storage hydro capacity be increased?

As old thermal power plants are decommissioned and renewables provide an increasing share of the electricity supply, storage capacity will need to grow if climate goals are to be met. Over the next two to three decades, Great Britain’s energy storage capacity alone will need to increase tenfold, from 3 gigawatts (GW) to around 30 GW.

Pumped storage hydro power stations require very specific sites, with substantial bodies of water between different elevations. There are hundreds, if not thousands, of potential sites around the UK, including disused mines, quarries and underground caverns, but the cost of developing entirely new facilities is huge. A more cost-effective way to increase storage capacity is by expanding existing plants, such as the Cruachan Power Station in Scotland.

Pumped Storage Hydro fast facts

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What is renewable energy?

17 December 2020

Sustainable bioenergy

These differ to non-renewable energy sources such as coal, oil and natural gas, of which there is a finite amount available on Earth, meaning if used excessively they could eventually run out.

Renewable resources can provide energy for a variety of applications, including electricity generation, transportation and heating or cooling.

The difference between low-carbon, carbon neutral and renewable energy

Renewables such as wind, solar and hydropower are zero carbon sources of energy because they do not produce any carbon dioxide (CO2) when they generate power. Low-carbon sources might produce someCO2, but much less than fuels like coal.

Bioenergy that uses woody biomass from sustainably managed forests to generate electricity is carbon neutral because forests absorb CO2 from the atmosphere as they grow, meaning the amount of CO2 in the atmosphere remains level. Supply chains that bring bioenergy to power stations commonly use some fossil fuels in manufacturing and transportation. Therefore woody biomass is a low carbon fuel, when its whole lifecycle is considered.

Managing forests in a sustainable way that does not lead to deforestation allows bioenergy to serve as a renewable source of power. Responsible biomass sourcing also helps forests to absorb more carbon while displacing fossil fuel-based energy generation.

Nuclear is an example of a zero carbon source of electricity that is not renewable. It does not produce CO2,but it is dependent on uranium or plutonium, of which there is a finite amount available.

Managing forests in a sustainable way that does not lead to deforestation allows bioenergy to serve as a renewable source of power.

How much renewable energy is used around the world?

Humans have harnessed renewable energy for millions of years in the form of woody biomass to fuel fires, as well as wind to power ships and geothermal hot springs for bathing. Water wheels and windmills are other examples of humans utilising renewable resources, but since the industrial revolution fossil fuels, coal in particular, have been the main source of power.

However, as the effects of air pollution and CO2 produced from burning fossil fuels become increasingly apparent, renewable energy is gradually replacing sources which contribute to climate change.

In the year 2000 renewable energy accounted for 18% of global electricity generation, according to the IEA. By 2019, renewable sources made up 27% of the world’s electrical power.

Why renewable energy is essential to tackling climate change

The single biggest human contribution to climate change is greenhouse gas emissions, such as CO2, into the atmosphere. They create an insulating layer around the planet that causes temperatures on Earth to increase, making it less habitable.

Renewable sources of electricity can help to meet the world’s demand for power without contributing to global warming, unlike carbon-intensive fuels like coal, gas and oil.

Bioenergy can also be used to remove CO2 from the atmosphere while delivering renewable electricity through a process called bioenergy with carbon capture and storage (BECCS).

Forests absorb CO2 from the atmosphere, then when the biomass is used to generate electricity the same CO2 is captured and stored permanently underground – reducing the overall amount of CO2 in the atmosphere.

Humans have used renewable energy for millions for years, from wood for fires to wind powering boats to geothermal hot springs. 

What’s holding renewables back?

The world’s energy systems were built with fossil fuels in mind. This can make converting national grids difficult and installing new renewable energy sources expensive. However, as knowledge grows about how best to manufacture, build and operate renewable systems, the cost of deploying them at scale drops.

There are future changes needed. Renewables such as wind, solar and tidal power are known as intermittent renewables because they can’t generate electricity when there is no sun, wind or the tidal movement. For future energy systems to deliver enough power, large scale energy storage, as well as other flexible, reliable forms of generation will also be needed to meet demand and keep systems stable.

Renewable energy key facts:  

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Turning waste into watts

3 September 2020

Sustainable bioenergy
Fields being ploughed by tractor

Think of carbon emissions and the image that comes to mind is often of industrial sites or power generation – not of what we eat and what we throw away. But food waste is a major contributor of greenhouse gas emissions.

Globally, food loss and waste from across the food chain generates the equivalent of 4.4 gigatonnes of carbon dioxide (CO2) a year, or about 8% of total greenhouse gas emissions.

But what if there was a way to reduce those emissions and generate power by using discarded food and other organic waste like grass cuttings or nut shells? A technology known as anaerobic digestion is increasingly making this idea a reality.

How anaerobic digestion works

All organic waste products have energy in them, but it’s tied up in the form of calories. When food and vegetation rots, microorganisms break down those calories into gases and other products.

Methane or Ammonium molecules. Science concept. 3D rendered illustration.

Methane or Ammonium molecules.

Exactly what these ‘other products’ are depends on whether there is any oxygen present. With oxygen, the products are water, CO2 and ammonia, but remove oxygen from the equation and a very valuable gas is produced: methane (CH4). The lack of oxygen is also what gives anaerobic digestion its name – when oxygen is present it becomes aerobic digestion.

During the anaerobic digestion process, bacteria and other microorganisms break down organic matter, gradually deteriorating complex polymers like glucose or starch into progressively simpler elements, such as alcohol, ammonia, CO2 and, ultimately, CH4, a biogas with huge potential as a fuel for other processes.

Anaerobic power in practice

The CH4 produced in anaerobic digestion is incredibly useful as a fuel – turn on a gas hob or stovetop and it’s predominantly methane that provides the fuel for the flame. The chemical compound is also the main component in the natural gas that makes up much of Great Britain’s electricity supply.

This means using anaerobic digestion to create CH4 out of waste products turns that waste into a valuable power source. But it’s not as simple as putting a bag over a rubbish tip and hoping for the best.

Instead, anaerobic digestion is carried out in large tanks called digesters. These are filled with feedstocks from biological substances that can include anything from food scraps, to alcohol and distillery waste, to manure. Under the right conditions microorganisms and bacteria begin to digest and breakdown these substances into their basic elements.

The air quantity and temperature of the digesters is carefully regulated to ensure the microorganisms have the best possible environment to carry out the digestion of the feedstock, with different types of feedstock and microorganisms operating best in different conditions.

The biogas created as a result of this digestion is then captured, ready to be turned into something useful.

biogas plant

Making use of biogas

Three different things can happen to the biogas produced during the course of the digestion. Locally, it can be combusted on-site to provide further heat to regulate the temperature of the anaerobic digestion units.

Or, it can be combusted in a combined heat and power (CHP) generator, where it can generate electricity to be used on site — for example to power a farm — or sold through energy suppliers such as Opus Energy onto wider regional or national electricity networks. This biogas electricity is an important element of Great Britain’s energy supply, accounting for 6,600 GWh or 7.3% of all power generated by solid and gaseous fuels in 2017.

Some of the biogas can even be cleaned to remove CO2, leaving behind pure methane that can be pumped onto natural gas grids and used to provide heat and power to households. Government research estimates a fully utilised biogas sector could provide up to 30% of the UK’s household gas demands.

After the digestion process has been completed and the biogas has been removed, what is left behind in the digester is a mass of solid matter called digestate. This is extremely rich in nutrients and mineral, such as potassium and nitrogen, making it an excellent soil enhancer.

Where anaerobic digestion is being used today

Today, much of anaerobic digestion power is generated on farms – unsurprisingly, given the ready access to biological waste material to use as feedstock. As well as a potential source of electricity and heat, it also gives farmers access to a new revenue stream, by selling electricity or biogas, as well as reducing utility and fertiliser costs.

While many of these installations are smaller scale, some can get quite big. Linstock Castle Farm in North Cumbria, for example, has a biogas facility with a 1.1 megawatt(MW) operating capacity, enough to power as many as 2,000 homes at a time. It was originally installed by the farmers as a more cost-effective way of growing their business than buying more dairy cows.

Biogas plant on a farm processing cow dung as a secondary business activity

There is, however, potential for anaerobic digestion to operate on an even larger scale. In the US, the city of Philadelphia is developing a system that will link all newly built households together into a network where food waste is automatically collected and transported to a biogas generating facility.

Closer to home, Northumbrian Water uses 100% of its sludge, the waste produced from purifying water, to produce renewable power via anaerobic digestion. It’s estimated to have reduced the carbon footprint of the facility’s operations by around 20%, and saved millions of pounds in savings on operating costs.

There have also been experiments with using biogas to power vehicles. The ‘Bio-Bus’ was the first bus in the UK to be powered by biomethane made from food, sewage and commercial liquid waste, and ran between Bath and Bristol Airport.

But anaerobic digestion power is not a magic bullet. It will be right in certain situations, but not all. If utilised effectively, anaerobic digestion and biogas could fill a vital role in national electricity and gas networks, while at the same time helping dispose of waste products in an environmentally-friendly and cost-effective way.

5 exciting energy innovations that you should know about in 2020

5 June 2020

Power generation

As we head into the 2020s, it’s an exciting time for energy. A deeper level of climate consciousness has led to crucial changes in populations’ attitudes and thinking around how we power our lives – adapting to a new set of energy standards has become essential.

It’s also driving innovation in energy technology, leading to the rise of a number of emerging technologies designed to support the global energy transition in new ways. From domestic solar and wind generation, to leaps forward in recycling and aeroplane fuel, here are five new energy ideas in the 2020s pipeline.

Miniature turbines for your garden

Think of a wind farm and you might think of giant structures located in remote, windswept areas, but that’s quickly changing.

IceWind is developing residential wind turbines that use the same generator-principal as large-scale wind farms, just on a much smaller scale. A set of three outer and three inner vertical blades rotate when the wind passes through them, providing spinning mechanical energy that passes through the generator and is converted to electricity.

Constructed from durable stainless steel, carbon fibre and aluminium, the CW1000 model can handle wind speeds of up to 134 miles per hour. To ensure they’re fit for domestic use, the units are adapted to have a maximum height of just over 3 metres and make less than 40 decibels of noise – roughly equivalent to quiet conversation.

The Icelandic company says it aims to decentralise and democratise energy generation by making wind power accessible to people anywhere in the world.

Expanding solar to cover more surfaces

As solar technology becomes more widespread and easier to implement, more communities are turning to a prosumer approach and generating their own power.

Roof panels to date have been the most common way to domestically capture and convert rays, but Solecco is taking it a step further, offering solar roof tiles. These work in the same way as roof panels, using photovoltaic cells made of silicon to convert sunlight into electricity. But by covering more surface area, entire roofs can be used to generate solar energy, rather than single panels.

Environmental Street Furniture takes it a step further by bringing small scale solar generation into many aspects of the urban environment such as smart benches, rubbish bins, and solar lighting in green spaces. This opens up opportunities for powering cities, including incorporating charging stations and network connectivity, which in turn enables social power sharing.

Re-purposing plastic 

Global recycling rates currently sit at approximately 18%, indicating there are still further steps to take in ensuring single-use products are eliminated.

Plastic is a major target in the war on disposal, and for good reason. By 2015, the world had produced over seven billion tonnes of plastic. Greenology is tackling this by harnessing a process called pyrolysis to turn plastic into power. By heating waste at a very high temperature without oxygen, the plastic is breaks down without combusting.

This process produces bio-oils, which can be used to create biofuels. The benefits of this innovative approach to waste are twofold: not only can plastic be repurposed, which minimises the lasting impact single-use plastic has on the planet, but the creation of biofuel offers a power source for everything from transport to generating electricity.

Storing heat for the home

Decarbonising heating is one of the global challenges yet to have a clear answer. Pumped Heat Ltd (PHL) is developing a potential solution with its heat battery technology. The company has found a solution that enables its devices to charge up and store electricity during ‘off-peak’ hours (when electricity is at its cheapest) and then use this energy to generate heating and hot water for homes as it is required. As the grid continues to decarbonise, and as renewable power becomes cheaper and more accessible, the electricity used to charge these units will approach zero carbon content.

The heat battery technology utilises vacuum insulation, losing 10 times less heat than a conventional night storage heater. In contrast, air sourced heat pumps (a more commonly used type of heat pump), operate in real time when a home needs heating. They take water at its delivery temperature (which can be very cold, during the winter months) and heat it using electricity available at that time. Pumped Heat’s storage system instead ensures there is always heat available, maintaining a consistent temperature for hot water or central heating, rather than just when there is an excess of electricity.

The company claims the benefit of using a heat battery system is that it is cheaper than an oil or LPG boiler, in a world where renewable electricity production, both domestic and on a national level, is only set to increase.

Waste-powered planes

As some of the most fossil fuel-reliant industries in the world, travel and transport are actively seeking alternative and more sustainable ways to keep them powered in long run.

Velocys aims to do this using waste. The company is developing sustainable fuels for aviation and heavy goods transport, using the Fischer-Tropsch method of gasifying waste. This involves turning waste materials – such as domestic refuse and woody waste – into clean jet fuel using a catalytic chemical reaction, where synthesis gases (carbon monoxide and hydrogen) are converted into liquid hydrocarbons that can then be used for fuel.

Not only does this make use of waste products that could have ended up in landfill, but it produces much cleaner fuels, that emit less particle matter and harmful pollutants into the atmosphere.

As we enter a new decade of invention, the world is focusing on more sustainable alternatives to power our lives, and these innovative solutions to current environmental issues will continue to inspire creativity.

Why spin a turbine without generating power?

12 February 2020

Power generation
Turbine at Cruachan Power Station

Massive spinning machinery is a big part of electricity generation whether it’s a wind turbine, hydro plant or biomass generator.

But big spinning turbines don’t just pump electricity out onto the grid. They also play a crucial role in keeping the electricity system stable, safe and efficient. This is because big, heavy spinning turbines add something else to the grid: inertia.

This is defined as an object’s resistance to change but in the context of electricity it helps the grid remain at the right frequency and voltage level. In short, they help the grid remain stable.

However, as electricity systems in Great Britain and other parts of the world move away from coal and gas to renewables, such as wind turbines, solar panels and interconnectors, the level of inertia on the system is falling.

“We need the inertia, we don’t need the megawatts,” explains Julian Leslie, Head of Networks at the National Grid Electricity System Operator (ESO). “But in today’s market we have to supply the megawatts and receive the inertia as a consequence.”

Turbine at Drax Power Station

Engineer inspecting turbine blades at Drax Power Station

The National Grid ESO is taking a new approach to this aspect of grid stability by using what are called synchronous condensers. These complicated-sounding pieces of machinery are actually quite straightforward in their concept: they provide inertia to the grid without generating unnecessary power.

These come in the form of:

  • Existing generators that remain connected to the grid but refrain from producing electricity.
  • Purpose built machines whose only function is to act as synchronous condensers, never generating real power. These may be fitted with flywheels to increase their mass and, in consequence, their inertia.

This means that spinning without generating is about to become a very important part of Great Britain’s electricity system.

Around and around

Electricity generators that spin at 3,000 rpm are described as synchronous generators because they are in sync with the grid’s frequency of 50Hz. These include coal, gas, hydro, biomass turbines and nuclear units. Most spin at 3000 rpm, some machines much less (e.g. 750 rpm). Thanks to the way they are designed, they are all synchronised together at the same, higher speed.

Then there are wind turbines where the generated power is not synchronised to the grid system. Termed asynchronous generators, these machines do not have readily accessible stored energy (inertia) and do not contribute to the stability of the system. Interconnectors and solar panels are also asynchronous.

It’s important that Great Britain’s whole grid is kept within 1% of the 50Hz frequency, otherwise the voltage of electricity starts to fluctuate, damaging equipment, becoming less efficient, even dangerous, or resulting in blackouts.

Say a power station or a wind farm were to drop offline, as occurred in August 2019, this would cause the amount of power on the grid to suddenly fall. But it is not just the power that changes – the frequency and voltage also fluctuate dramatically which can cause equipment damage and ultimately, towns, cities or widespread areas to lose power.

Running machines that have inertia act like the suspension on a car – they dampen those fluctuations, so they are not as drastic. The big spinning machines keep spinning, buying valuable milliseconds for the grid to react, often automatically, before the damage becomes widespread.

However, as a consequence of decarbonisation, more solar panels and wind turbines are now on the system and there are fewer spinning turbines, leading to lower levels of inertia on the grid.

“There are periods when renewable generation and flow from interconnectors are so great that it displaces all conventional, rotational power plants,” says Leslie. “Today, bringing more inertia onto the grid may mean switching off renewables or interconnectors, and then replacing them with rotating plants and the megawatts associated with that.”

Creating a market for inertia and synchronous condensers offers a new way forward – providing inertia without unneeded megawatts or emissions from fossil fuels.

A new spin on grid stability

At the start of 2020, The National Grid ESO began contracting parties, including Drax’s Cruachan pumped-hydro power station, to operate synchronous condensers and provide inertia to the grid when needed.

The plans mark a departure from the previous system where inertia and voltage control from electricity generators was taken for granted.

Cruachan Power Station is already capable of running its units in synchronous condenser mode (one of its units, opened up for maintenance, is pictured at the top of this article). This involves an alternator acting as a motor, offering inertia to the grid without generating unneeded electricity. Other service providers will repurpose existing turbines, construct new machines or develop new technologies that can electronically respond to the grid’s need for stability.

Synchronous condensers, or the idea of spinning a turbine freely without generating power, are not new concepts; power stations in the second half of the 20th century could shut down certain generating units but keep them spinning online for voltage control.

In the 1960s and 70s, some substations – where the voltage of electricity is stepped up and down from the transmission system – also deployed stand-alone synchronous condensers. These were also used to provided inertia as well as voltage control but are long since decommissioned.

Synchronous condenser installation at Templestowe substation, Melbourne Victoria, Australia. By Mriya via Wikimedia.

“Synchronous condensers are a proven technology that have been used in the past,” says Leslie. “And there are many new technologies we are now exploring that can deliver a similar service.”

Cheaper, cleaner, more stable

Commercial UK wind turbines

The National Grid ESO estimates the technology will save electricity consumers up to £128 million over the next six years. Savings, which come from negating the need for the grid to call upon fossil fuels for inertia as coal, oil and gas, become increasingly uneconomical across the globe as carbon taxes grow.

The fact that synchronous condensers do not produce electricity also saves money the grid may have had to pay out to renewable generators to stop them producing electricity or to storage systems to absorb excess power.

“It means the market can deliver the renewable flow without the grid having to pay to restrain it or to pay for gas to stabilise the system,” says Leslie. “Not only does this allow more renewable generation, but it also reduces the cost to the consumer.”

In a future energy system, where there is an abundance of renewable electricity generations, synchronous condensers will be crucial in keeping the grid stable. The National Grid ESO’s investment in the technology further highlights the importance of new ideas and innovation to balance the grid through this energy transition.

Synchronous generation provides benefits to system stability beyond the provision of inertia. In a subsequent article we’ll also explore how synchronous condensers can assist with voltage stability and help regional electricity networks and customers to remain connected to the national system during and after faults.

Read about the past, present and future of the country’s electricity system in Could Great Britain go off grid? 

How the market decides where Great Britain gets its electricity from

11 June 2019

Power generation
Set of vintage glowing light bulbs on black background

The make-up of Great Britain’s power system changes constantly. Demand is always changing; in winter it may peak at 50 gigawatts (GW) but overnight in summer it will be less than 20 GW. Some days wind is the biggest source of the country’s electricity generation, other days it’s gas. Then there are days when, for a few hours, solar takes the top spot in the middle of the day and nuclear during the night.

In the past, Great Britain’s electricity came almost entirely from big coal and nuclear power stations. But as the need for decarbonisation has grown, so has the number of sources feeding electricity to the grid, creating an ever more complex and varied system made up of technologies that behave in very different ways. For example, some sources are weather dependent and can’t generate all day every day others stop and start flexibly to smooth out changes in demand or intermittent generation.

But in the event all sources are available, what dictates which sources actually generate, and when? The overriding influence is economics – the costs of starting up and running a turbine, the price of fuel or taxes on carbon emissions.

In Great Britain, electricity’s wholesale price is not set in stone by an entity such as a regulator. Instead it’s negotiated via trading over the course of a day between generators (power stations, storage and wind turbines) and suppliers, who transmit that electricity to consumers.

As a result, the price of electricity fluctuates every half hour, responding to factors such as demand, cost of fuels, availability of resources (such as sun and wind), and carbon taxes.

For an example of the scale at which it fluctuates, we can look at the period 1-4 June this year, when the index price of electricity ranged from over £55/MWh down to around £5/MWh (see chart, above).

But while these figures speak to the overall price of a megawatt on the system, they don’t reflect all the individual sources, nor their individual costs. Each of the multiple sources on the grid have their own operating costs fluctuating on a similar basis.

These changing prices give rise to what is known as the merit order, a fluid, theoretical ranking of generation sources. This is not set by any regulator, economist or even by traders. Rather it is a naturally occurring, financial occurrence that explains what sources of electricity generation are feeding power onto the grid day-to-day.

What is the merit order?

The merit order dictates which sources of generation will deliver power to the grid by ranking them in ascending order of price together with the amount of electricity generated. This then determines the order in which power sources are brought onto the system. Ultimately, suppliers want the right amount of electricity for the best possible price, so in a system made up of many sources, it is the lowest cost, highest yield option that is brought online first, which in theory helps keep overall electricity prices down.

North Sea Wind Farm, Redcar

This means it is often sources such as wind and solar, which have no fuel costs, that sit at the top of the merit order. Nuclear may come next as it continually generates a large amount of power for a low cost, while taking a long time to turn down or off. At the opposite end of the merit order are sources like coal and oil, which have high fuel and carbon dioxide (CO2) emission costs (such as carbon taxes and the European Emission Trading scheme).

However, the merit order isn’t a set of hard and fast rules. “It’s an assumption used by traders or market commentators to guide what is likely to run and thereby the likely market price,” says Ian Foy, Drax Head of Ancillary Services. “There is no published merit order. It is like Santa Claus – it doesn’t exist, but it makes explaining Christmas easier.”

 The intricacies of being in and out of merit

If a generating unit is required to meet demand then it’s described as ‘in merit’, if it is not required at any particular point in time then it’s ‘out of merit’ – there’s no point in suppliers paying for another power station, for example, to start generating if demand is already being met.

“If the market is efficient, we generate from the lowest cost source at all times,” says Foy. “Costs are not simple, for example, you have to take into account the cost of starting or shutting down generating units. However, costs are not publicly shared so there’s no single view of the merit order. Each party has its own perspective on it.”

It means the merit order changes from season-to-season, day-to-day and hour-to-hour, as rates of supply and demand, and the availability of resources change.

Dungeness Nuclear Power Station in Kent

“An obvious example is gas tends to be cheaper in summer than winter, when it’s not being used for heating. Coal and gas also switch as global prices change,” says Foy. “Availability also changes over the year. There’s more solar in summer, but none in the morning and evening peaks of winter.”

There are also practical issues, such as repairs being made on wind and hydro turbines or planned maintenance outages on thermal and nuclear power stations, putting those generators out of action and knocking them out of merit.

And because the merit order is not an implemented working scheme, it can be deliberately manipulated by outside forces. One of the ways this is most clearly seen is in carbon pricing.

Merit in a changing system

The Carbon Price Support tax paid by coal and gas generators in Great Britain, alongside the European Emissions Trading System have increased the cost of fossil fuel generation: gas, oil and coal. Levied as £/tonne of CO2 emitted this has the effect of pushing fossil generation down the merit order. With coal emitting double the CO2 per unit of electricity compared to gas, we can see how the merit order can be influenced to achieve environmental outcomes.

This has helped steer Great Britain towards record breaking coal-free periods and stimulated the building of low carbon generation sources.

Other sources, such as interconnection with Europe and power storage facilities, also slot into the merit order. Their position often shifts due to highly variable prices dependent on power generation in neighbouring countries or the amount of electricity that can be stored at a low cost, respectively.

The grid is ever-changing. Over the last two decades we’ve seen huge shifts in how power is generated and delivered. This is unlikely to slow down in the near future, but the merit order will remain. Like the grid, it is in a constant state of change, adapting to the many moving parts of the electricity system. As long as Great Britain maintains its open electricity trading market, the merit order will continue to dictate where the country’s power comes from.

How getting renewable energy from your supplier actually works

2 April 2019

Sustainable bioenergy

Where does our electricity come from? One answer might be the power stations, wind turbines and solar panels that generate it. You might even go as far as to say the wind, sun, water, biomass and gas powering those stations. Or even the network companies transporting that power around the country. But there’s also a very important middle-man in this process: electricity suppliers.

Most of Great Britain gets its power from one of the ‘Big Six’ energy suppliers, which buy electricity from the wholesale market and then sells it to consumers. However, with more businesses and consumers looking for less carbon-intense electricity sources, there are now a whole host of smaller companies taking on the incumbents and offering all-renewable electricity.

From Ovo to Bulb to Drax’s own Haven Power and Opus Energy, consumers and businesses have more and greener options than ever about where to buy their electricity, with many even offering 100% renewable electricity.

But how do these companies ensure the megawatts powering homes, offices and street lights come from renewable sources?

Cleaning up the river

The electricity we use doesn’t just flow through a single cable from a power station to our houses. It travels through what’s called the transmissions system, which is run by National Grid ESO and local distribution network operators.

Apart from off-grid installations like solar panels on buildings, some of which are unable to export their unused power, all the electricity generated by different sources around the country goes into this same system. It means megawatts generated by a wind turbine get mixed up with those generated by a nuclear reactor or a coal power station.

Think of it as a river. Although it is its own entity, it is fed by multiple streams of water coming from different sources. In the case of electricity, megawatts from various generators are fed into a central system, which then enter homes, offices and devices around the country.

So, what makes green power generated from renewable sources, green power used in homes?

Suppliers can’t control exactly what megawatts you use, but they can influence the makeup of the overall ‘river’ your electricity is pulled from by what electricity they agree to buy and offer to their customers.

Renewable suppliers match the amount of electricity their customers use with the amount they buy from renewable sources. So, if a home uses 4 megawatt-hours (MWh) a year, a supplier will need to ensure it buys an equal amount of power from National Grid, which National Grid sources from generators. If that supplier offers 100% renewable power, it will need to ensure it has the right kinds of deals in place with renewable generators to deliver that amount of power.

It means that while the river of electricity is still a mix from different streams, more of the water will come from renewable streams. Therefore, if more homes and businesses switch to renewable suppliers, more of the overall river will be renewable, which will in turn help to decarbonise the electricity system, enabling a lower-carbon economy.

But how does this fit into the existing electricity business and infrastructure?

But how do suppliers actually buy renewable power from generators?

The business of electricity

To understand how suppliers ensure they are buying renewable power you first need to understand how the business works. Or at least, how it used to. The most obvious place to start is with the generators.

Be they gas power stations or an offshore wind farm, the generator is where electricity is produced and are often owned by a supplier.

Suppliers can buy electricity from their own generators, often months or years ahead of delivery. But if there is a shortfall, the supplier can also buy electricity on the wholesale market, where other generators can sell their electricity.

Because suppliers are on a competitive market, their aim is to buy the electricity for the lowest possible price and sell it for more – but at a better rate than rivals. Measures like carbon prices or green incentives help lower the cost of renewable and low-carbon generation, and position it as a more economically viable purchase than more expensive fossil fuels like coal.

Renewable-only suppliers also want to buy electricity as cheap as possible and sell it as affordably as possible. But unlike standard suppliers they only buy electricity from renewable sources.

This can be done by purchasing electricity from independent renewable generators on the wholesale market, or arranged through what are known as Power Purchase Agreements (PPAs) – longer-term contracts between generators and suppliers agreeing on a specific amount of power.

The advantage of these for the renewable generator is it secures revenue for the future, while for the supplier it means a dependable source of electricity. For large installations, these deals are often signed before construction even begins to ensure investors there will be a return.

Transitioning to a low-carbon electricity system, however, is not just about suppliers buying more electricity from renewable sources.

The future of electricity suppliers

As more businesses, individuals and communities are becoming prosumers and generating their own electricity, the wider role of the supplier in the system is changing.

The government’s feed-in-tariffs financially reward customers for generating their own electricity, even if they don’t export it to the grid. But even small generators can sign deals with suppliers to sell electricity through schemes such as Good Energy’s SmartGen policy, which is open to generators with between 10 and 100 kilowatts (kW) of installed capacity. Similarly Opus Energy helps over 2,100 businesses sell more than 1,100 gigawatt-hours (GWh) of excess wind, solar, anaerobic digestion and hydro power.

For larger prosumer businesses, the relationship with suppliers and the grid is different. Rather than the traditional buying and selling of electricity, it requires a cooperative approach to understand how the prosumer can best utilise their assets.

Beyond increasing the amount of low-carbon electricity, decarbonising the electricity system also means making more efficient use of energy and managing the data that can help improve efficiency. Haven Power’s partnership with Thames Water sees it analyse an average of 68 million half-hour smart meter readings every year, using the data to help the company improve its billing and forecasting. As the wider system becomes more intelligent, suppliers will be able to better forecast how much electricity its customers use and help them reduce their consumption.

The role required of suppliers in a changing system will create opportunities for more renewable and efficient use of electricity. And empower more consumers to get their electricity from low-carbon sources that can help to make the whole country’s electricity greener.

Want a different perspective on the same story? Watch TV’s Jonny Ball explain.

Where does global electricity go next?

12 December 2018

Power generation

Since the Paris Agreement came into effect in November 2016, it’s fair to say many countries have taken up the vital challenge of decarbonisation in earnest.

However, not all are making progress at the same rate. Many are not implementing the agreement at the pace needed to mitigate climate change, and keep the average global temperature increase well below 2oC of pre-industrial levels. Certainly not enough to limit the increase to 1.5oC by 2050, which the majority of climate scientists believe is necessary for the planet is to avoid dire consequences.

Last year even saw renewable energy investment fall 7%, while the money going into fossil fuels grew for the first time since 2014. And data released by the International Energy Agency (IEA) at the beginning of this month’s UN Climate Change Conference (COP24) in Katowice, Poland, found that 2017 was also the first for five years seeing an increase in advanced economies’ carbon emissions.

Despite this, there is much positive work towards decarbonisation.

A new report, Energy Revolution: A Global Outlook, by academics from Imperial College London and E4tech, commissioned by Drax, looks into the core areas and activities required to decarbonise the global energy system – and which countries are performing them to good effect. In doing this, the report also looks at how the UK stands in comparison and what steps countries need to take to truly decarbonise.

Here are the key indicators of decarbonisation and how countries around the world are performing towards them.

Dam in Hardangervidda, Norway

Clean power

At the forefront of reducing emissions and curbing climate change is the need to decarbonise electricity generation and move towards renewable sources.

Last year the global average carbon intensity was 440 grams of carbon dioxide (CO2) per kilowatt-hour (g/kWh). Out of the 25 major countries the report tracks, 16 came in below average, with seven of these falling under the long-term 50 g/kWh goal.

Leading the rankings are Norway, France and New Zealand, which have a near-zero carbon intensity for electricity generation, thanks to extensive hydro and nuclear power capacity.

At the other end of the table, China, India, Poland and South Africa remain wedded to coal, producing up to twice the global average CO2 for electricity generation. This comes despite China having installed two and a half times more renewables than any other country – it now boasts 600 gigawatts (GW) of renewable capacity.

Per person, Germany is leading the renewablesdrive with almost 1 kW of wind and solar capacity installed per person over the last decade. Despite this, as much as 40% of its electricity still comes from coal.

Part of the challenge in moving away from coal to renewables is economic, as many countries continue to subsidise their coal industries to keep electricity affordable. Phasing out these subsidies is therefore key to switching to a low-carbon generation system. Doing this works, as demonstrated by the example of Denmark, which cut its fossil fuel subsidies by 90% over the past decade, in turn successfully cutting its coal generation by 25%.

The UK’s carbon pricing strategy, which adds £16 per tonne of CO2emitted on top of the price set by the European emissions trading system (EU ETS), has led the carbon intensity of Great Britain’s electricity to more than halve in a decade. It highlights how quickly and effectively these kinds of fees can make fossil fuels uneconomical. Since 2008 the UK has removed more than 250 g/kWh from its electricity production.

Carbon capture and storage

In many future looking climate scenarios, keeping the earth’s temperature below a 2oC increase depends on extensive deployment of carbon capture technology – capturing as much as 100 billion tonnes of CO2 per year. Storing and using carbon is clearly forecast to be a major part of any attempt to meet the Paris Agreement, but at present there are few facilities carrying it out at scale.

Around the world today there are 18 large-scale carbon capture and storage (CCS) units running across six countries with a total capacity to capture 32 million tonnes of CO2 per year (MtCO2p.a). Another five facilities are under construction in three countries to add another 7 MtCO2p.a of global capacity. In the UK, Drax Power Station is piloting a bioenergy carbon capture and storage programme that could make it the world’s first negative emissions power station.

The USA has the greatest total installed capacity at 20 MtCO2p.a., but per person it ranks behind Norway, Canada and Australia. Their smaller populations give them more than 200 kg of carbon capture capacity per person per year.

Oil platform off the coast of Australia

These figures are well below the 100 billion tonnes the IEA estimates need to be stored by 2060 to prevent temperatures reaching 2oC more. However, considering the US alone has a potential storage capacity of more than 10 trillion tonnes of CO2, the potential of storage is not expected to be a problem.

Using depleted oil or natural gas fields as storage for captured carbon is being explored in a number of regions, with the US establishing several projects with more than 1 million tonnes in capacity. In 2019, Australia will open the world’s largest CO2store with the capacity to capture between 3.4 million and 4 million tonnes a year from Chevron’s Gorgon gas facility.

Considering the storage capacity available globally, it’s a matter of deploying the necessary technology for CCS to have a significant impact on emissions and global warming. The UK is perhaps a typical example of where CCS is at present with estimated storage capacity of 70 billion tonnes, as much as half of the entire EU combined. By repurposing North Sea oil and gas fields in partnership with Norway, the UK could pool its carbon storage capacity.

Electrification

Electricity generation is one of the main targets for emissions reductions globally. As a result of the progress that’s been made in this field, many future-looking scenarios highlight the important of electrification in other sectors, such as transport, in turn making them less carbon intensive.

Transport is leading the charge globally – there are now 10 different countries where one of every 50 new vehicles sold is electric. In Norway, this ratio is almost one in two, thanks in part to generous tax exemptions as well as non-financial incentives like access to bus lanes and half-price ferries.

Perhaps surprisingly, China is the world’s largest electric vehicle (EV) market. It may still use significant amounts of coal, but its commitment to reducing urban air pollution has seen it push EVs heavily, and it now accounts for 50% of the global battery EV market on its own.

Chinese electric car charging stations

Of course, adoption of EVs requires the supporting infrastructure to be truly successful. In conjunction with its high sales, Norway leads the way in charging points per capita, with one for every 500 people. This compares to one charger for every 5,000 people in the UK and one for every 10,000 people in China.

Electrification also affects the energy intensity of country’s transport systems and while it may be the largest EV market, China’s rise in private vehicles has been largely driven by petrol and diesel models. The result is the largest increases in transport energy intensity and emissions has taken place in China, Indonesia and India, respectively.

Domestic energy intensity is also rising in China, Indonesia and South Africa, as greater numbers of people gain access to appliances and home comforts. Conversely in Europe, Portugal, Germany and the Netherlands have all seen their domestic energy intensity drop in the last decade. However, this may be the lingering effect of the 2008 recession rather than long-term efficiency improvements.

The efficiency of industrial processes is also an important barometer in decarbonisation. Activities like mining and manufacturing require heavy-duty diesel-powered machinery and often coal-powered generators, especially in BRIC nations. The exception is China, where plans to get the 1,000 most energy-intensive companies to reduce their energy consumption per unit of GDP produced by 20% over the last five years, has proved fruitful.

Norway’s heavily-electrified industries, however, are still energy intensive and its level of carbon intensity is vulnerable to fluctuations in power generation prices.

Electrification and reduced emissions require government policies to put in motion behavioural changes that can lead to lasting decarbonisation. “Robust carbon pricing is one of the most effective tools to enabling a zero carbon, lower cost energy future,” Drax Group CEO Will Gardiner commented recently.

Welcoming a November report by the Energy Transitions Commission, Gardiner said:

“The cost of inaction far outweighs the cost of doing something now.”

Explore the full report: Energy Revolution: A Global Outlook.

I. Staffell, M. Jansen, A. Chase, E. Cotton and C. Lewis (2018). Energy Revolution: Global Outlook. Drax: Selby.

Drax commissioned independent researchers from Imperial College London and E4tech to write Energy Revolution: A Global Outlook, which looks into the core areas and activities required to achieve decarbonisation – and which countries are performing them to good effect. In doing this it also looks at how the UK stands in comparison and what steps countries need to take to truly decarbonise.