Q1 2021: Britain’s transition from coal to biomass to BECCS

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Dr Nina Skorupska CBE, CEO — The Association for Renewable Energy & Clean Technology (REA); Dr Iain Staffell, Professor Richard Green, Professor Tim Green and Dr Malte Jansen — Imperial College London

Britain moved one step closer to its 2024/25 target of phasing out coal power completely, while biomass generation hit new record highs.  

On the 5th of March Drax announced that it had ceased commercial power generation from coal[1]after 47 years at the UK’s largest power station.  This leaves just two coal power stations operating in Britain, as 85% of the country’s coal fleet have retired over the last ten years.

Meanwhile, biomass power stations reached new records, generating 3.81 GW on 27th of March. Biomass output is likely to grow further, as a new biomass-powered combined heat and power unit at Teesside is expected to come online later this year.

Global leadership

Currently, biomass supplies 2% of the world’s electricity, though this share is higher in Europe, having grown five-fold since 2000 to hit 6% in 2020.[2] One explanation for this comes from countries such as Denmark and Sweden, which have extensive municipal electricity and combined heat and power production.

Another reason is the UK.  Our share of electricity generation from biomass has tripled over the past decade, hitting an all-time high of 11% in 2020[2].  This means the UK has the highest share of electricity production from biomass of any large country (ones with over 100 TWh/year electricity demand).The UK pioneered large-scale use of biomass for electricity generation, contributing to its world-leading success in decarbonising electricity over the last decade. This position means the UK has also played a major part in developing the science-led sustainability criteria that govern the use of biomass.

Share of electricity generated from biomass in 2020 across all countries worldwide which consume more than 100 TWh of electricity per year2

The transition from coal to biomass to BECCS[1] outlines the versatility of biomass for electricity generation to contribute at each stage of the decarbonisation journey. In a high-coal system (the UK’s past), biomass conversions allow for rapid carbon reductions whilst utilising existing infrastructure and preserving the reliable functionality of firm, dispatchable power. In a high-renewables system (increasingly the UK’s present), biomass offers flexibility services, including inertia and grid balancing. This helps the overall system to integrate variable renewables and lowers grid management costs. Finally, looking to the future, BECCS offers the possibility of negative emissions, which the Climate Change Committee describe as “a necessity” for net zero and beyond. 

Looking to the past

Coal dominated Britain’s electricity generation until just a decade ago.  However, since 2018, Britain has produced more electricity from biomass than it has from coal.  There are three main reasons why Britain’s coal plants closed down.

Clean air legislation forced older plants to close if they did not fit equipment to capture harmful sulphur and nitrous oxide emissions.  Secondly, many plants closed on economic grounds, either because they were reaching the end of their design life and the cost of maintaining them outweighed the revenue they could bring in, or they could simply no longer compete in the market.  A key factor in this was government policy raising the cost of emitting carbon so coal plants became more expensive than gas.  With demand falling and renewables taking a larger share, there was simply no room left for them to make a profit.

The change in coal power station capacity over the last decade and main categories of coal plant closures

When these units retired they needed to be replaced by a clean electricity source that could provide baseload generation, producing electricity when it is needed.  However, research shows that in addition, these coal retirements also led to a 30% increase in output from natural gas plants (37 TWh extra in 2019).[4]

The third source of coal plant closures was conversion to biomass.  Although they represent the smallest share of capacity (with 3.2 GW converted), they have delivered greater carbon savings because not only did they reduce the amount of coal burnt, they replaced it with a low-carbon source of electricity.  Coal to biomass conversions therefore limited – rather than increased – gas generation.  Comparing 2012 to 2019, they reduced carbon emissions by 10 MtCO2 per year, slightly more than achieved by the 8 GW of onshore wind farms installed in that time.2

Looking to the future

National Grid ESO’s Future Energy Scenarios see biomass playing an increased role in coming decades.  Current unabated biomass (where emissions from generating electricity are offset by regrowing it) plays a key step towards the deployment of BECCS (bioenergy with carbon capture and storage) from the late 2020s.  

Bioenergy (the ‘BE’ in ‘BECCS’) operates by growing and continuously regrowing plants that are then used for energy.  The carbon emitted during energy generation is reabsorbed by the regrowth of the plants, meaning net-zero emissions.  Supply chain emissions are then counted on top of this in accordance with a strict sustainability governance regime, hence Electric Insights considers biomass as producing 121 grams of CO2 per kWh of electricity.  

Annual electricity generation from solid fuels in Britain and the average carbon intensity of electricity, shown over the past three decades and the next three decades according to National Grid’s “Leading the Way” future energy scenario

If emissions from the power station are instead captured and locked away underground (the ‘CCS’ in ‘BECCS’), the plants being grown and regrown actually remove carbon from the atmosphere, over and above simply offsetting the bioenergy emissions. Therefore BECCS as a whole can deliver negative emissions as part of a major energy source.

The deployment of BECCS means annual carbon emissions from electricity generation could fall negative as early as 2030 in National Grid’s scenarios.  By the mid-2030s, BECCS could be removing 40 MtCO2 per year from the atmosphere, comparable to total annual emissions in 2020.

The IEA remarked in 2018 that “modern bioenergy is the overlooked giant of the renewable energy field”.  With the potential for sustainable expansion and the use of carbon capture to deliver negative emissions, this could take a more visible role in the UK’s future.

[1] These units will still operate in the capacity market until they are fully decommissioned in 2022, meaning they could be called upon to provide peak capacity at times of system stress.

[2] Data from Ember’s Global Electricity Review

[3] Bioenergy with carbon capture and storage

[4] R Green and I Staffell, 2021. The contribution of taxes, subsidies and regulations to British electricity decarbonisation.  EPRG 2105.

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