Tag: decarbonisation

What is the carbon cycle?

3 March 2023

Carbon capture

What is the carbon cycle?

All living things contain carbon and the carbon cycle is the process through which the element continuously moves from one place in nature to another. Most carbon is stored in rock and sediment, but it’s also found in soil, oceans, and the atmosphere, and is produced by all living organisms – including plants, animals, and humans.

Carbon atoms move between the atmosphere and various storage locations, also known as reservoirs, on Earth. They do this through mechanisms such as photosynthesis, the decomposition and respiration of living organisms, and the eruption of volcanoes.

As our planet is a closed system, the overall amount of carbon doesn’t change. However, the level of carbon stored in a particular reservoir, including the atmosphere, can and does change, as does the speed at which carbon moves from one reservoir to another.

What is the role of photosynthesis in the carbon cycle?

Carbon exists in many different forms, including the colourless and odourless gas that is carbon dioxide (CO2). During photosynthesis, plants absorb light energy from the sun, water through their roots, and CO2 from the air – converting them into oxygen and glucose.

The oxygen is then released back into the air, while the carbon is stored in glucose, and used for energy by the plant to feed its stem, branches, leaves, and roots. Plants also release CO2 into the atmosphere through respiration.

Animals – including humans – who consume plants similarly digest the glucose for energy purposes. The cells in the human body then break down the glucose, with CO2 emitted as a waste product as we exhale.

CO2 is also produced when plants and animals die and are broken down by organisms such as fungi and bacteria during decomposition.

What is the fast carbon cycle?

The natural process of plants and animals releasing CO2 into the atmosphere through respiration and decomposition and plants absorbing it via photosynthesis is known as the biogenic carbon cycle. Biogenic refers to something that is produced by or originates from a living organism. This cycle also incorporates CO2 absorbed and released by the world’s oceans.

The biogenic carbon cycle is also called the “fast” carbon cycle, as the carbon that circulates through it does so comparatively quickly. There are nevertheless substantial variations within this faster cycle. Reservoir turnover times – a measure of how long the carbon remains in one location – range from years for the atmosphere to decades through to millennia for major carbon sinks on land and in the ocean.

What is the slow carbon cycle?

In some circumstances, plant and animal remains can become fossilised. This process, which takes millions of years, eventually leads to the formation of fossil fuels. Coal comes from the remains of plants that have been transformed into sedimentary rock. And we get crude oil and natural gas from plankton that once fell to the ocean floor and was, over time, buried by sediment.

The rocks and sedimentary layers where coal, crude oil, and natural gas are found form part of what is known as the geological or slow carbon cycle. From this cycle, carbon is returned to the atmosphere through, for example, volcanic eruptions and the weathering of rocks. In the slow carbon cycle, reservoir turnover times exceed 10,000 years and can stretch to millions of years.

How do humans impact the carbon cycle?

Left to its own devices, Earth can keep CO2 levels balanced, with similar amounts of CO2 released into and absorbed from the air. Carbon stored in rocks and sediment would slowly be emitted over a long period of time. However, human activity has upset this natural equilibrium.

Burning fossil fuel releases carbon that’s been sequestered in geological formations for millions of years, transferring it from the slow to the fast (biogenic) carbon cycle. This influx of fossil carbon leads to excessive levels of atmospheric CO2, that the biogenic carbon cycle can’t cope with.

As a greenhouse gas that traps heat from the sun between the Earth and its atmosphere, CO2 is essential to human existence. Without CO2 and other greenhouse gases, the planet could become too cold to sustain life.

However, the drastic increase in atmospheric CO2 due to human activity means that too much heat is now retained between Earth and the atmosphere. This has led to a continued rise in the average global temperature, a development that is part of climate change.

Where does biomass fit into the carbon cycle?

One way to help reduce fossil carbon is to replace fossil fuels with renewable energy, including sustainably sourced biomass. Feedstock for biomass energy includes plant material, wood, and forest residue – organic matter that absorbs CO2 as part of the biogenic carbon cycle. When the biomass is combusted in energy or electricity generation, the biogenic carbon stored in the organic matter is released back into the atmosphere as CO2.

This is distinctly different from the fossil carbon released by oil, gas, and coal. The addition of carbon capture and storage to bioenergy – creating BECCS – means the biogenic carbon absorbed by the organic matter is captured and sequestered, permanently removing it from the atmosphere. By capturing CO2 and transporting it to geological formations – such as porous rocks – for permanent storage, BECCS moves CO2 from the fast to the slow carbon cycle.

This is the opposite of burning fossil fuels, which takes carbon out of geological formations (the slow carbon cycle) and emits it into the atmosphere (the fast carbon cycle). Because BECCS removes more carbon than it emits, it delivers negative emissions.

Fast facts

  • According to a 2019 study, human activity including the burning of fossil fuels releases between 40 and 100 times more carbon every year than all volcanic eruptions around the world.
  • In March 2021, the Mauna Loa Observatory in Hawaii reported that average CO2 in the atmosphere for that month was 14 parts per million. This was 50% higher than at the time of the Industrial Revolution (1750-1800).
  • There is an estimated 85 billion gigatonne (Gt) of carbon stored below the surface of the Earth. In comparison, just 43,500 Gt is stored on land, in oceans, and in the atmosphere.
  • Forests around the world are vital carbon sinks, absorbing around 7.6 million tonnes of CO2 every year.

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Carbon markets will be essential in reaching net zero – we must ensure they support high standards

9 November 2022

Carbon capture

Angela Hepworth, Commercial Director, Drax

In brief:

  • The voluntary carbon market will be essential in deploying engineered carbon removals technologies like Bioenergy with carbon capture and storage (BECCS), and direct air carbon capture and storage (DACS) at scale.
  • The Integrity Council for the Voluntary Carbon Market is developing a set of Core Carbon Principles (CCPs).
  • Drax support proposed principals if they’re applied in ways appropriate for engineered carbon removals.
  • Standards around additionality and the permeance of carbon removals may apply very differently to nature-based and engineered removals, something that needs to be addressed explicitly.

There’s growing recognition, in governments and environmental organisations, of the urgent need to develop high-integrity engineered carbon removals at scale if the world has any chance of meeting our collective Paris-aligned climate goals.

Bioenergy with carbon capture and storage (BECCS), and direct air carbon capture and storage (DACS) are two technologies on the cusp of deployment at scale that can remove carbon from the atmosphere and store it permanently and safely. The technology is proven, developers are bringing forward projects, and the most forward-thinking companies are actively seeking to buy removal credits from BECCS and DACS developers.

Yet there’s a risk that the frameworks being developed in the voluntary carbon market could stifle rather than support the development of engineered carbon removals.

Drax is a world-leader in the deployment of bioenergy solutions. Our goal is to produce 12 million tonnes of high-integrity, permanent CO2 removals by 2030 from its BECCS projects in the U.K. and the U.S. We support the development of rigorous standards for CO2 removals that give purchasers confidence in the integrity of the CO2 removals they’re buying. Such standards are also important in providing a clear framework for project developers to work to.

However, the market and its standards have largely developed around carbon reduction and avoidance credits, rather than removals. To create a market that can enable engineered carbon removals at scale, re-thinking is needed to create standards that are fit for purpose to tackle the climate emergency.

Core Carbon Principles

The Integrity Council for the Voluntary Carbon Market is in the process of developing a set of Core Carbon Principles (CCPs) and Assessment Framework (AF) intended to set new threshold standards for high-quality carbon credits.

At Drax, we welcome and support the principals proposed by the Integrity Council. However, it’s crucial they’re applied in ways that are appropriate for engineered carbon removals, and support rather than prevent their development.

Many CCPs are directly applicable to engineered carbon removals and can offer important standards for projects developing removals technologies. Among the most important principals include those stating:

  • Removals must be robustly quantified, with appropriate conservatism in any assumptions made.
  • Key information must be provided in the public domain to enable appropriate scrutiny of the carbon removal activity, while safeguarding commercially sensitive information.
  • Removal credits should be subject to robust, independent third-party validation and verification.
  • Credits should be held in a registry which deals appropriately with removal credits.
  • Registries must be subject to appropriate governance, to ensure their integrity without becoming disproportionately bureaucratic or burdensome.
  • Removals must adhere to high standards of sustainability, taking account of impacts on nature, the climate and society.
  • There should be no double counting of carbon removals between corporates, or between countries. Bearing in mind that both corporates and countries may count the same removals in parallel, and that the Article 6 mechanism means countries can decide whether trades between corporates should or shouldn’t trigger corresponding adjustments to countries’ carbon inventories.

However, as pioneers in the field, we believe that two of the Core Carbon Principles need to be adapted to the specific characteristics of engineered carbon removals.

Supporting additionality and development incentives

The CCPs state: “The greenhouse gas (GHG) emission reductions or removals from the mitigation activity shall be additional, i.e., they would not have occurred in the absence of the incentive created by carbon credit revenues.”

Engineered carbon removal credits such as BECCS and DACS are by their nature additional. They are developed for the specific purpose of removing CO2 from the atmosphere and putting it back in the geosphere. They also rely on revenue from carbon markets – largely the voluntary market at present, but potentially compliance markets such as the U.K. and E.U. ETS in the future.

However, most early projects are likely to have some form of Government support (e.g., 45Q in the U.S., or Contracts for Difference in the U.K.) from outside carbon credit revenues. But that support isn’t intended to be sufficient on its own for their deployment – project developers will be expected to sell credits in compliance or voluntary markets.

Engineered carbon removals have high up-front capital costs, and it’s clear that revenue from voluntary or compliance markets will be essential to make them viable.

Additionality assessments should be risk-based. If it’s clear that a technology-type is additional, a technology-level assessment should be sufficient. This should be supplemented with full transparency on any government support provided to projects.

Compensating against non-permanent storage

On the topic of permeance that CCPs state: “The GHG emission reductions or removals from the mitigation activity shall be permanent, or if they have a risk of reversal, any reversals shall be fully compensated.”  A key benefit of engineered carbon removals with geological storage is that they effectively provide permanent carbon removal. Any risk of reversal over tens of thousands of years is extremely small.

The risk of reversal for nature-based credits, by contrast, is much greater. Schemes for managing reversal risk in the voluntary carbon market that have been developed for nature-based credits, are not necessarily appropriate for engineered removals.

Requirements for project developers to set aside a significant proportion of credits generated in a buffer pool, potentially as much as 10%, are disproportionate to the real risk of reversal from a well-manged geological store. They also fail to take account of the stringent regulatory requirements for geological storage that already exist or are being put in place.

Any ongoing requirements for monitoring should be consistent with existing regulatory requirements placed on storage owners and operators. Similarly, where jurisdictions have robust regulatory arrangements for dealing with CO2 storage risk, which place liabilities on storage owners, operators, or governments, the arrangements in the voluntary carbon market should mirror these arrangements rather than cutting across them, and no additional liabilities should be put on project developers.

At Drax, we believe the CCPs provide a suitable framework to ensure the integrity of engineered carbon removals. If applied pragmatically, they can give purchasers of engineered carbon removal credits confidence in the integrity of the product they’re buying and provide a clear framework for project developers. They can ensure that standards support, rather than stifle the development of high integrity carbon removal projects such as BECCS and DACS, which are essential to achieving our global climate goals.

Why and how is carbon dioxide transported?

11 April 2022

Carbon capture

What is carbon transportation?

Carbon transportation is the movement of carbon from one place to another. In nature, carbon moves through the carbon cycle. In industries like energy, however, carbon transportation refers to the physical transfer of carbon dioxide (CO2) emissions from the point of capture to the point of usage or storage.

Why does carbon need to be transported?

Anthropogenic (man-made) CO2 released in processes like power generation leads to the direct increase of CO2 in the atmosphere and contributes to global warming.

However, these emissions can be captured as part of carbon capture and storage (CCS). The CO2 is then transported for safe and permanent storage in geological formations deep underground.

Capturing and storing CO2 prevents it from entering the atmosphere and contributing to global warming. Processes that can deliver negative emissions – such as bioenergy with carbon capture and storage (BECCS) and direct air capture and storage (DACS) – aim to permanently remove CO2 from the atmosphere through CCS.

In CCS, carbon must be transported from the site where it’s captured to a site where it can be permanently stored. This means it needs to travel from a power station or factory to a geological formation like a saline aquifer or depleted oil and gas reservoirs.

As of September 2021, there were 27 operational CCS facilities around the world, with the combined capacity to capture around 40 million tonnes per annum (Mtpa) of CO2. It’s estimated that the UK alone has 70 billion tonnes of potential CO2 storage space in sandstone rock formations under the North Sea.

How is carbon transported?

CO2 can be transported via trucks or ships, but the most common and efficient method is by pipeline. Moving gases of any kind through pipelines is based on pressure. Gases travel from areas of high pressure to areas of low pressure. Compressing gas to a high pressure allows it to flow to other locations.

Gas pipelines are common all around the world, including those transporting CO2. In the US there are, for instance, more than 50 CO2 pipelines – covering around 6,500 km and transporting approximately 68 million tonnes of CO2 a year.

Gas takes up less volume when it’s compressed, and even less when it is liquefied, solidified, or hydrated. Therefore, before being transported, captured CO2 is often compressed and liquefied until it becomes a supercritical fluid.

In a supercritical state, CO2 has the density of a liquid but the viscosity (thickness) of a gas and is, therefore, easier to transport through pipelines. It’s also 50-80% less dense than water, with a viscosity that is 100 times lower than liquid.

This means it can be loaded onto ships in greater quantities and that there is less friction when it’s moving through pipes and, subsequently, into geological storage sites.

How safe is it to transport carbon?

It’s no riskier to transport CO2 via pipeline or ship than it is to transport oil and natural gas, and existing oil and natural gas pipelines can be repurposed to transport CO2.

To enable the safe use of CO2 pipelines, CCS projects must ensure captured CO2 complies with strict purity and temperature specifications, as well as making sure CO2 is dry and free from impurities that could impact pipelines’ operations.

Whilst there are a growing number of CCS transport systems around the world, CCS is still is a relatively new field but research is underway to identify best practises, materials and technologies to optimise the process. This includes research around potential risks and techniques for leak mitigation and remediation.

In the UK, the Health and Safety Executive regulates health, safety, and integrity issues for all natural gas pipelines, which are covered by legislation. The legislation ensures the safety of pipelines, pressure systems and offshore installations and can serve as a strong foundation for CO2 transport regulation.

Fast facts

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How is carbon stored?

13 January 2022

Carbon capture

Carbon storage is the process of capturing and trapping that CO2. This can occur naturally in the form of carbon sinks like forests, oceans, and soils that store carbon. However, it can also be manually carried out through technology.   

One of the most well-established ways of storing carbon through the use of technology is by injecting CO2 into naturally occurring geological formations that can lock in or sequester the molecule on a permanent basis. Carbon storage is the final phase of the carbon capture, usage, and storage (CCUS) process.

Why do we need to store carbon?

Global bodies like the UN’s Intergovernmental Panel on Climate Change (IPCC), as well as the UK’s own Climate Change Committee, emphasise carbon capture and storage as crucial to achieving net zero emissions and meeting the Paris Agreement’s goal of limiting temperature rises to within 1.5oC.

This includes supporting forest growth through afforestation and reforestation, and other nature-based solutions to store carbon, alongside CCUS technology.

The European Commission also highlights CCUS’s role in balancing increased energy demand and continued fossil fuel use in the future, with the need to reduce greenhouse gas emissions and prevent them entering the atmosphere.

How is carbon captured and transported to storage?

In naturally occurring examples, forests and ocean fauna absorb carbon through photosynthesis. When the vegetation eventually decomposes the carbon is sequestered into soil and seabeds.

Carbon can also be captured from emissions sources such as factories or power plants. The carbon is captured either pre-combustion, where it is removed from the fuel source, or post-combustion, where it is removed from exhaust fumes in the form of CO2.

The CO2 is then converted into a supercritical state where it has the viscosity of a gas but the density of a liquid, meaning it can travel more easily through pipelines. It can also be transported via trucks and ships, but pipelines are the most efficient.

Where can carbon be stored?

Natural carbon sinks differ all over the world, from peatlands in Scotland to Pacific coral reefs to the massive forests that cover countries like Russia, Canada, and Brazil. Wooden buildings also act as carbon storage as they maintain the carbon within the wood for long time periods.

The CO2 captured by manmade technologies can also be stored in different types of geological formation: unused natural gas reserves, saline aquifers, and un-minable coal mines.

The North Sea, with its expansive layers of porous sandstone, also offers the UK alone an estimated 70 billion tonnes of potential CO2 storage space.

If negative emissions technologies (which actively remove emissions from the atmosphere) were to capture and store the equivalent amount of CO2 as the 258 million tonnes expected to remain in the UK economy in 2050, it would take up just 0.36% of the available storage space.

Years of research by the oil and gas industries mean many such geological structures have been mapped and are well understood all around the world.

Carbon storage fast facts

How is the carbon kept in place?

In nature-based carbon sinks the carbon does not always remain in one location. In a forest, for example, trees and plants will hold carbon until the end of their lifetime after which they decompose, releasing some CO2 into the atmosphere while some is sequestered into soil.

When CO2 captured through CCUS is stored several things can happen to it in a geological storage site. It can be caught in the minute intervening spaces within the rock through capillary action, or trapped by a layer of impermeable cap-rock, which prevents it from moving upwards.

CO2 may also dissolve in the water and then sinks as it is heavier than normal water. The carbonated water reacts with basaltic rocks which cover most of the ocean floor. The reaction releases elements like calcium, magnesium, and iron into the water stream. Over time, these elements combine with the dissolved CO2 to form stable carbonate minerals that permanently fill pores within the rock.

How does CO2 enter the storage sites?

The CO2 is injected into the porous rocks of depleted or unused natural gas or oil reserves, as well as saline aquifers – geologic strata, filled with brine or saline water. Porous rock is filled with holes and gaps between the grains that make up the rock. When CO2 is injected into these structures, the CO2 floods the pores, displacing the brine or remnants of oil and gas. It then spreads out and is trapped in the dome-like structures of the rock strata called anticlines.

How long can CO2 be stored?

Appropriately selected and maintained geological reservoirs are “very likely” to retain 99% of sequestered carbon for more than 100 years and are “likely” to retain 99% of sequestered carbon for more than 1,000 years, according to the 2005 Special Report on CCS by the IPCC. Another study by Nature found that more than 98% of injected CO2 will remain stored for over 10,000 years.

In natural carbon sinks, the length of time that carbon is stored varies and depends on environments being preserved. Peatland, for example, builds up over thousands of years storing carbon. However, as peatlands degrade from attempts to drain them to create arable land, as well as peat extraction for fuel, they begin to emit CO2. The lifecycle of a tree by contrast is relatively short before it decomposes and releases some CO2 back into the atmosphere.

The ability for geological storage to contain CO2 for millennia means it can truly remove and permanently store emissions.

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Expanding Cruachan: An epic energy storage project to help unlock a renewable future

12 January 2022

Power generation
Loch Awe from Cruachan

At the beginning of March 2021, Britain experienced its longest ‘wind drought’ in a decade. For eleven days, wind output averaged just 11% of the UK electricity mix – less than a quarter of the average output in the month before and the month after. The power system was able to cope as gas power stations made up most of the shortfall.

But keeping the lights on will become increasingly challenging as electricity generation shifts from carbon-intensive coal and gas towards weather-dependent wind and solar technologies, where supply is variable and intermittent. One solution to maintain a stable, resilient power supply as the electricity system decarbonises is increasing the amount of long-duration energy storage that can plug gaps and balance the gird.

Pumped hydro storage – a tried and tested solution

The largest-capacity form of electricity storage by far, pumped storage hydro plays a key role in the energy mix and stabilising the grid. Which is why, following a feasibility study, Drax has kickstarted plans to extend our pumped hydro storage power station at Cruachan in the Scottish Highlands.

By drilling a second cavern inside Ben Cruachan, Cruachan 2, to the east of the original power station, will add up to 600 MW in generating capacity, more than doubling the site’s total capacity to more than 1GW. It’s an epic project and one that could provide power for around a million homes.

The original Cruachan facility has been supplying and absorbing excess power to the grid since 1965. Acting as a ‘green battery’, it stores low-carbon energy when there is over supply and releases it when demand is high.

Designed at a time when the grid was powered by nuclear or coal-fired plants that could only adjust output slowly, Cruachan’s technology is still cutting edge and has proved equally successful at balancing more volatile supply and demand as power generation has shifted towards renewables and low-carbon sources.

“Cruachan plays a critical role in the UK energy system today because it provides a unique range of services for a single asset – it can both generate electricity at 440 MW but it can also pump which means it takes that power off the system so in effect you can deploy greater renewable resources. And if there’s too much wind in the system, rather than curtail wind farms you can pump to take 482 MW off the system,” says Steve Marshall, Development Manager at Cruachan 2.

Cruachan Power Station

Pumped Storage Hydro (PSH) at Cruachan Power Station [click to view/download]

Enabling more renewables on the system

As Marshall points out, too much wind can be as problematic as too little. With the government’s ambition to quadruple offshore wind capacity by 2030 to 40 gigawatts (GW), the grid will have to manage significantly more wind-generated power, and consequently much greater fluctuations in supply.

Currently, the demand left to be met by renewable generation ranges from 10 GW to 30 GW throughout the year. But modelling by Imperial College London suggests that with 40 GW of offshore wind this range could expand, from 30 GW right down to minus 30 GW, in other words, renewables would produce significantly more than national demand. Without long-term storage capacity, this energy will be wasted, forcing the grid to pay wind farms to stop generating.

“There’s a lot of offshore wind coming online in Scotland that has to be transported through the transmission system to England where the demand is,” says Marshall. “The transmission system in 2030 could become saturated more than 20-30% of the time because there’s too much renewable power. You have a choice: either build more transmission lines or more energy storage that can take that power off the system.”

Turbine Hall at Cruachan Power Station

Plugging the inertia gap

As well integrating more renewables into the electricity mix, the Cruachan expansion may also help meet the inertia shortfall. Inertia – stored kinetic energy – acts as a ‘shock absorber’ in the system, smoothing out sudden changes in power supply and demand and ensuring that frequency remains stable at 50 Hz. This is a critical, as just 1% variation above or below this standard can damage equipment and infrastructure.

Many renewable technologies, such as wind turbines and solar PV panels, aren’t built around spinning turbines that synchronise with the grid and so lack inherent inertia. Cruachan’s turbines, on the other hand, spin at 500/600rpm and produce electricity at the grid frequency of 50 Hz providing inertia that helps the grid remain stable. Indeed in 2020, National Grid ESO contracted a unit at Cruachan to provide inertia 24/7 as part of a 6 year contract

“The grid calls on Cruachan three to four hundred times a month, with generation mode changes ranging from hours to very short bursts,” explains Marshall. Increasing the number of turbines would allow Cruachan to respond to a greater range of the grid’s needs.

“With more units you have more flexibility,” says Marshall. “If you start to change the generating unit sizes to 150 MW or 200MW machines you get different levels of inertia that offers more options to the grid.”

Building on Cruachan’s legacy

While automated drilling processes mean that the rock will no longer need to be excavated by ‘Tunnel Tigers’, the crews that hand-drilled, blasted, and excavated granite from the mountainside, Cruachan 2 will still create an estimated 300 jobs during peak construction and support around 900 jobs across the country. And by bringing around 300 GW a year of renewable energy to the grid, and reducing requirement for further transmission lines the expansion has the potential to save consumers more than £350 million in energy costs by 2050.

“With the increased deployment of renewables there is a need for more assets like Cruachan,” says Marshall. The ambition is to have Cruachan 2 operational by 2030 and work could start as early as 2024.

But progress is dependent on the government providing support through a revenue stabilisation mechanism for such a long-term, large-scale energy storage project. A study by KPMG found that a Cap and Floor regime, similar to what has unlocked a wave of investment in cross-border inter-connectors, could be the best mechanism for long-duration storage. If this is forthcoming, the expansion could play a vital role in stabilising the grid and smoothing the UK’s transition to a net zero power system.

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.

The jobs needed to build a net zero energy future

11 November 2021

Sustainable business

Many components are needed to tackle climate change and reach environmental milestones such as meeting the goals of the Paris Agreement. One of those components is the right workforce, large enough and with the necessary skills and knowledge to take on the green energy jobs of a low-carbon future. In 2020, the renewable energy sector employed 11.5 million people around the world, but as the industry continues to expand that workforce will only grow.

Last year, a National Grid report found that in the UK alone, 120,000 jobs will need to be filled in the low-carbon energy sector by 2030, to meet the country’s climate objectives. That figure is expected to rise to 400,000 by 2050.  The UK energy sector as a whole currently supports 738,000 jobs and much of this workforce already has the skills needed for a low carbon society . Others can be reskilled and retrained, helping to bolster the future workforce by supporting employees through the green transition.

At a global level energy sector jobs are expected to increase from 18 million to 26 million by 2050. Jobs that will span the full energy spectrum; from researching and advising on low-carbon solutions to installing and implementing them.

Here are some of the roles that will be key to the low-carbon energy transformation:

A wind farm under construction off the English coast

Wind turbine technicians

According to the International Energy Agency (IEA), wind power is this year set for a 17% increase in global energy generation compared to 2020, the biggest increase of any renewable power source. The IEA also forecasts that wind power will need to grow tenfold by 2050 if the world is to meet the goals of the Paris Agreement. It’s not surprising, therefore, that wind turbine technicians – the professionals who install, inspect, maintain, and repair wind turbines – are in high demand. In the US, wind turbine technician is the fastest-growing job in the country – with 68% growth projected over the 2020-2030 period – to give just one example.

In the UK, many wind turbine technicians have a background in engineering or experience from the wider energy sector. Although there are wind turbine technician and maintenance courses available, they are not a prerequisite, and many employers offer apprenticeships and on-the-job training – smoothing the path for energy professionals to transition into the role.

Solar panel installers

Today, solar photovoltaic (solar PV) is the biggest global employer in renewable energy, accounting for 3.8 million jobs. The IEA also reported a 23% uptick in solar PV installations around the world in 2020. In the UK, there are currently 13.2 gigawatts (GW) of installed solar power capacity. Trade association Solar Energy UK predicts this will need to rise to at least 40 GW by 2030 if the UK is to succeed in becoming a net zero economy by 2050. The trade association believes this could see the creation of 13,000 new solar energy jobs.

Solar panel installers – who carry out the important job of installing and maintaining solar PV – are essential to a low-carbon future. Many solar panel installers in the UK come from a background in electrical installation or have transitioned from engineering. While there are training courses specifically designed for solar panel installers, they are not a necessity, particularly if you already have on-the-job experience in a relevant sector. This makes a move to becoming a solar panel installer relatively easy for someone already working in energy or with a mind for engineering.

Energy consultants

Businesses of all kinds must play a role in the transition to net zero. Organisations must be able to manage their energy use and begin switching to renewable sources. As professionals who advise companies on this process, renewable energy consultants are a key part of the green energy workforce. Aspects of the job include identifying how organisations use their electric assets and helping businesses optimise those assets to build responsiveness and flexibility into energy-intensive operations. The core responsibilities of a renewable energy consultant are to reduce a company’s environmental impact while helping the business reduce energy costs and identifying opportunities.

Carbon accountants

A growing number of businesses are setting targets for reducing their greenhouse gas (GHG) emissions. But that’s only possible if you can first determine what your GHG emissions are and where they come from, which is where the relatively young field of carbon accounting comes in. Through what is known as physical carbon accounting, companies can assess the emissions their activities generate, and where in the supply chain the emissions are occurring. This allows businesses to implement more accurate actions and be realistic in their timelines for reducing emissions.

On a wider scale, accurate carbon accounting will be crucial in certifying emissions reductions or abatement, as well as in the distribution of carbon credits or penalties as whole economies push towards net zero.

Battery technology researchers

Energy storage is essential to a low-carbon energy future.  The ability to store and release energy from intermittent sources such as wind and solar will be crucial in meeting demand and balancing a renewables-driven grid. While many forms of energy storage already exist, developing electric batteries that can be deployed at scale is still a comparatively new and expanding area.

Global patenting activities in the field of batteries and other electricity storage increased at an annual rate of 14% –  four times faster than the average for technology – between 2005 and 2018. However, it’s estimated that to meet climate objectives, the world will need nearly 10,000 GW hours of battery and other electricity storage by 2040. This is 50 times the current level and research and innovation will be crucial to delivering bigger and more efficient batteries.

Farmers and foresters

How we use and manage land will be important in lowering carbon emissions and creating a sustainable future for people and the planet. Crops like corn, sugarcane, and soybean can serve as feedstock for biofuel and bioenergy, and farming by-products such as cow manure can be used in the development of biofuel.

Techniques adopted in the agricultural sector will also be important in optimising soil sequestration capabilities while ensuring it is nutrient-rich enough to grow food. These techniques include the use of biochar, a solid form of charcoal produced by heating biomass without oxygen. Research indicates that biochar can sequester carbon in the soil for centuries or longer. It also helps soil retain water and could contribute to reducing the use of fertilisers by making the soil more nutrient-dense.

Forests, meanwhile, provide material for industries like construction, the by-products from which can serve as feedstock for woody biomass, primarily in the shape of low-grade wood that would otherwise remain unused. Sustainably managed forests, such as those from which Drax sources its biomass, have two-fold importance. They both enable woody biomass for bioenergy and ensure CO2 is removed from the atmosphere as part of the natural carbon cycle.

Biofuel engineers and scientists

Farmers and foresters provide feedstock for biofuels, but it’s biofuel scientists and engineers who research, develop, and enhance them, opening the door to alternative fuels for vehicles, heating, and even jet engines.

According to the IEA, production of biofuel that can be used as an alternative to fossil fuels in the transport sector grew 6% in 2019. However, the organisation forecasts that production will need to increase 10% annually until 2030to be in line with Paris Agreement climate targets.

Scientific innovations that can help boost the production of biofuel around the world, therefore, continues to be vital. As is the work of biofuel engineers who assess and improve existing biofuel systems and develop new ones that can replace fossil fuels like petrol and diesel.

The wealth of knowledge around fuels in the oil and gas industries means there is ample opportunity for scientists and engineers who work with fossil fuels to bring their skills to crucial low-carbon roles.

Geologists

The overriding goal of the Paris Agreement is to limit global warming to “well below” 2 and preferably to 1.5 degrees Celsius, compared to pre-industrial levels. This is an objective the IEA has said will be “virtually impossible” to fulfil without carbon capture and storage (CCS) technologies. CCS entails capturing CO2 and transporting it for safe and permanent underground storage in geological formations such as depleted oil and gas fields, coal seams, and saline aquifers.

According to the Global CCS Institute, the world will need a 100-fold increase on the 27 CCS project currently in operation by 2050. Knowledge and research into rock types, formations, and reactivity will be important in helping identify sites deep underground that can be used for safe, permanent carbon storage, and sequestration. Skills and expertise gained in the oil and gas industries will allow professionals in these sectors to make the switch from careers in fossil fuel to roles that help power a net zero economy.  

Employees working at Drax Power Station

Chemists

The role of chemists is also vital to decarbonisation. Knowledge and research around CO2 is a potent force in the effort to reduce and remove it from the atmosphere.

Technologies like CCS, bioenergy with carbon capture and storage (BECSS) and direct air carbon capture and storage (DACCS) are based around such research. Carbon capture processes are chemical reactions between emissions streams and solvents, often based on amines, and GHGs. Understanding and controlling these processes makes chemistry a key component of delivering carbon capture at the scale needed to help meet climate targets.

Chemists’ role in decarbonisation is far from limited to carbon capture methods. From battery technology to reforestation, chemists’ understanding of the elements can help drive action against climate change.

Bringing together disciplines

Tackling climate change on the scale needed to achieve the aims of the Paris Agreement depends on collaboration between industries, countries, and disciplines. Decarbonisation projects such as the UK’s East Coast Cluster, which encompasses both Zero Carbon Humber and Net Zero Teesside, fuse engineering and construction jobs with scientific and academic work.

Zero Carbon Humber, which brings together 12 organisations, including Drax, is expected to create as many as 47,800 jobs in the region by 2027. Among these are construction sector jobs for welders, pipefitters, machine installers and technicians. In addition, indirect jobs are predicted to be created across supply chains, from material manufacturing to the logistics of supporting a workforce.

Meeting climate challenges and delivering projects on the scale of Zero Carbon Humber, depends on creating an energy workforce that combines the knowledge of the past with the green energy skills of the future.

Drax’s apprenticeships have readied workers for the energy sector for decades, and will continue to do so as we build a low-carbon future. Options include four-year technical apprenticeships in mechanical, electrical, and control and instrumentation engineering. Getting on-the-job training and practical experience, apprentices receive a nationally recognised qualification, such as a BTEC or an NVQ Level 3, at the end of the programme.

Apprentices at Drax Power Station [2021]

The workforce needed to make low carbon societies a reality will be a diverse one – stretching from apprentices to experienced professionals with a background in traditional or renewable energy. It will also span every aspect of the renewable energy field, from the chemists and biofuel scientists who develop key technologies to the solar panel installers and wind turbine technicians who fit and maintain the necessary equipment.

The skills needed to take on these roles are already plentiful in the UK and around the world. Overcoming challenges on the road to net zero requires refocussing these existing talents, skills, and careers towards a new goal.

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 CO2 from 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 CO2 from the atmosphere as they grow. Atmospheric CO2 released 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 CO2 is 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 CO2 across 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 direct air carbon capture and storage (DACS)?

9 July 2021

Carbon capture

What is direct air carbon capture and storage (DACS)?

Direct air carbon capture and storage (DACS, sometimes referred to as DAC or DACCS) is one of the few technologies that can remove carbon dioxide (CO2) from the atmosphere. Unlike other carbon removal technologies that capture CO2 emissions during the process of generating electricity or heat, DACS can be deployed anywhere in the world it can tap into a supply of electricity.

CO2 removal is crucial to meeting the international climate goals set by the 2015 Paris Agreement. But it’s not enough just to cut CO2 emissions, to achieve net zero, it will also be necessary to remove the CO2 that two centuries of industrialisation have released into the environment. As a technology that removes more CO2 from the atmosphere than it releases – assuming it is powered by green electricity – DACS has the potential to play a key role in this process.

Key direct air capture facts

How does DACS work?

DACS could be described as a form of industrial photosynthesis. Just as plants use photosynthesis to convert sunlight and CO2 into sugar, DACS systems use electricity to remove CO2 from the atmosphere using fans and filters.

Air is drawn into the DACS system using an industrial scale fan. Liquid DACS systems pass the air through a chemical solution which removes the CO2 and returns the rest of the air back into the atmosphere.

Solid DACS systems captures CO2 on the surface of a filter covered in a chemical agent, where it then forms a compound. The new compound is heated, releasing the CO2 to be captured and separating it from the chemical agent, which can then be recycled.

The captured CO2 can then be compressed under very high pressure and pumped via pipelines into deep geological formations. This permanent storage process is known as ‘sequestration’.

Alternatively, the CO2 can be pumped under low pressure for immediate use in commercial processes, such as carbonating drinks or cement manufacturing.

A 2021 study by the Coalition for Negative Emissions shows that DACS could provide at least 1Gt of sustainable negative emissions by 2025

DACS fast facts

What role can DACS play in decarbonisation?

CO2 is in the air at the same concentration everywhere in the world. This means that DACS plants can be located anywhere, unlike carbon capture systems that remove CO2 from industrial processes at source.

There are 15 DACS plants currently in operation worldwide – Climeworks operates three in Switzerland, Iceland and Italy. Together, these small-scale plants capture approximately 9,000 tonnes of CO2 per annum. The first large-scale plant, currently being developed in the Permian Basin, Texas, is expected to capture 1,000,000 tonnes (one megatonne) per annum when it becomes operational in 2025.

At just 0.04%, the concentration of CO2 in the atmosphere is very dilute which makes removing and storing it a challenge. This means that DACS costs significantly more than some other CO2 capture technologies – between $200 and $600 (£156-468) per metric tonne. The process also requires large amounts of energy, which adds to the demand for electricity.

However, DACS has the potential to become an important piece in the jigsaw of CO2 removal technologies and techniques that includes nature-based solutions such as planting forests, along with bioenergy with carbon capture and storage (BECCS), soil sequestration and ‘blue carbon’ marine initiatives.

Go deeper

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