- BECCS combines carbon dioxide removal (CDR) and carbon capture and storage (CCS) by converting CO₂-absorbing biomass into energy and capturing the emissions.
- Sources of biomass include fast-growing crops, forestry residues, agricultural waste, and potentially algae.
- Captured CO₂ is compressed and transported to suitable geological storage sites.
- Ongoing research aims to improve energy conversion efficiency, lower capture costs, and assess environmental and social impacts.

Bioenergy is derived from biomass—organic material like plants and, in some cases, animal waste.

Main production methods:
1. Combustion – biomass is burned to produce heat and generate electricity.
2. Fermentation – microorganisms convert biomass into biofuels such as ethanol.
3. Gasification – biomass is heated with limited oxygen to produce syngas (mainly carbon monoxide and hydrogen), which can be used as fuel.

How is bioenergy different from burning fossil fuels?
Although energy from biomass may be generated through similar methods—such as combustion—its carbon origin is fundamentally different. The CO₂ released during bioenergy production comes from biogenic sources, meaning it was recently absorbed from the atmosphere by living plants. This carbon is part of the short-term carbon cycle—the natural exchange of carbon between the atmosphere and living plants, which absorb CO₂ through photosynthesis and release it again when they are burned for energy or when they die and decompose. As a result, it does not add new CO₂ to the atmosphere..

In contrast, fossil fuels are derived from ancient organic matter stored underground for millions of years. Burning them releases fossil carbon, introducing long-stored CO₂ into the atmosphere and increasing its overall concentration.

However, the climate benefit of bioenergy depends not only on the carbon source, but also on the full range of associated lifecycle emissions—greenhouse gases released during the cultivation, harvesting, transport, and processing of biomass. These indirect emissions are essential to consider when evaluating whether bioenergy delivers meaningful carbon reductions.

If the CO₂ produced during bioenergy generation is captured and permanently stored, the process becomes a form of negative emissions technology—one that removes more greenhouse gases from the atmosphere than it emits.

BECCS qualifies as a negative emissions technology because:

- Plants absorb CO₂ as they grow.
- The CO₂ released when the biomass is converted into energy is then captured and permanently stored.
- If the total CO₂ stored exceeds the emissions generated throughout the process—including cultivation, transport and processing—the result is net removal of CO₂ from the atmosphere.

BECCS appears in many net-zero strategies because it offers the potential to remove carbon dioxide from the atmosphere while also producing energy, thereby reducing reliance on fossil fuels. Most climate solutions focus either on cutting emissions or removing carbon from the atmosphere; BECCS is distinctive in offering both.

The material used in BECCS—known as biomass feedstock—comes from a variety of sources:

- Purpose-grown energy crops, such as switchgrass and fast-growing trees
- Agricultural residues—the leftover parts of crops that are not used for food, such as corn stalks, wheat straw, and rice husks
- Forestry residues, including sawdust, small branches, and other by-products of timber production.
- Biodegradable household and commercial waste, such as food, garden clippings, cardboard and paper
- Algae, which are cultivated in water rather than on land, allowing biomass to be produced without competing for farmland or food crops

Municipal waste often contains both biogenic carbon (from food, paper, and plant material) and fossil carbon (from plastics and synthetic materials). For BECCS to contribute to carbon removal, it’s important to determine how much of the captured CO₂ comes from biogenic sources.

This can be assessed using carbon isotope analysis, specifically by measuring Carbon-14. While organic materials contain measurable levels of Carbon-14, fossil-derived materials such as plastics—being millions of years old—contain virtually none.

By analysing the Carbon-14 content in captured CO₂, scientists can estimate the proportion that originates from biogenic sources. This helps clarify how much CO₂ has actually been removed from the atmosphere, rather than simply preventing new fossil emissions.

BECCS can only function effectively as a negative emissions technology if the biomass is sourced sustainably.

Key considerations include:

- Avoiding land use changes that lead to deforestation or loss of biodiversity
- Ensuring that biomass production does not compete with food supply or place pressure on water resources
- Minimising the energy and emissions involved in cultivation, harvesting, and transport, so that they do not exceed the energy generated
- Ensuring that the overall process results in a net reduction in atmospheric CO₂

Lifecycle emissions include all greenhouse gas emissions associated with BECCS—from the initial stages of biomass cultivation through to CO₂ storage. Understanding the full lifecycle is essential to determining whether BECCS actually reduces CO₂ levels.

These emissions can arise from:

- Growing and harvesting the biomass
- Transporting it to power generation facilities.
- Processing and converting it into energy
- Capturing, transporting, and storing the resulting CO₂
- Building and maintaining the necessary infrastructure

Accurately assessing CO₂ removal involves:

- Biomass growth – Measuring how much CO₂ is absorbed during plant growth, including changes in soil carbon
- Supply chain emissions – Accounting for emissions from cultivation, harvesting, transport, and conversion to energy
- Capture efficiency – Determining how much CO₂ is actually captured at the facility
- Lifecycle analysis – Bringing all these factors together to assess the net CO₂ removed from the atmosphere

BECCS relies on several carbon capture technologies, each designed to separate CO₂ from biomass energy systems. The three main approaches are:

- Post-combustion capture
This is the most widely used method. CO₂ is removed from flue gases after the biomass is burned, typically by using a liquid solvent that absorbs the CO₂. The gas is then separated from the solvent by heating. This method is often preferred because it can be retrofitted to existing power plants and industrial sites.

- Pre-combustion capture
In this approach, biomass is first converted into syngas (a mixture of hydrogen and carbon monoxide). The carbon monoxide is then converted to CO₂, which is captured before the fuel is burned.

- Oxy-fuel combustion
Biomass is burned in pure oxygen rather than air, producing a flue gas that is mostly CO₂ and water vapour. Once the water is removed, the resulting stream of CO₂ is easier to capture and compress for storage.

For BECCS to work at scale, the captured CO₂ must be transported—often over long distances—to secure <b>geological storage sites</b>, such as former oil and gas reservoirs or deep underground rock formations filled with salty water (known as saline aquifers).

This will likely involve a combination of pipelines and shipping, depending on geography and location.

Deploying BECCS at a scale that meaningfully contributes to climate goals presents several significant challenges:

- Land use – Producing sufficient biomass could require large areas of land, potentially competing with food production and natural ecosystems
- Sustainable supply – Biomass must be cultivated and harvested in ways that avoid soil degradation, excessive water use, and unintended emissions. Ethical concerns—such as impacts on local food security, labour conditions, and land rights—must also be addressed. These concerns are not resolved simply by sourcing biomass from distant regions; sustainability standards must apply globally.
- Costs – BECCS is currently more expensive than many other energy sources or carbon removal methods, which limits its commercial viability
- Infrastructure – Widespread deployment requires major investment in CO₂ transport and long-term storage systems
- Energy efficiency – Capturing and compressing CO₂ consumes energy, which reduces the overall efficiency of BECCS facilities
- Technical integration – Combining bioenergy production with carbon capture technologies remains complex and requires further development
- Public acceptance – Large-scale land use changes and CO₂ storage projects may face opposition over environmental or safety concerns
- Policy uncertainty – Stable, long-term policies and incentives are needed to support investment and guide implementation

BECCS should not be viewed as a standalone solution but as one component in a broader portfolio of climate strategies. Its success will depend on efficient capture technologies, sustainable and ethically sourced biomass, and robust infrastructure for CO₂ transport and storage. Ethical concerns—such as land use, food security, and social impacts—must be addressed wherever biomass is grown, not outsourced to distant regions. Continued research, pilot projects, and comprehensive lifecycle assessments will be essential to determine BECCS’s role and value in global climate mitigation efforts.

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