As the UK races to decarbonize its energy grid and achieve ambitious climate targets, biofuels have become a popular yet contentious topic in the renewable energy conversation. In theory, biomass—organic material from plants and animals—can offer a low-carbon alternative to fossil fuels. However, a closer look at how biomass is used to generate electricity reveals a more complex reality. Some biofuel-sourced electricity on the UK grid comes from biomass plants that burn waste materials in incinerators, a practice that may have a carbon footprint rivalling, or even exceeding, that of coal.


The Promise of Biomass and Biofuels
Biomass energy production uses organic materials such as wood, agricultural residues, and sometimes animal waste to generate electricity. Theoretically, biofuels are “carbon-neutral,” as the carbon dioxide (CO₂) released during combustion is roughly equal to the amount absorbed during the material's growth. With proper management, biofuel sources can be replenished, making this energy source sustainable over time.

In practice, biofuels, including wood pellets, municipal waste, and agricultural residues, have become an integral part of the UK’s renewable energy mix. The UK’s Renewable Obligation Certificates (ROC) scheme provides incentives for electricity generated from renewable sources, including biofuels, which has encouraged biomass plants across the country to ramp up production.


When Biofuels Aren’t So Green
Biofuels, however, aren’t always as sustainable as they may seem. A significant portion of biofuel-generated electricity in the UK comes from biomass plants that use waste incineration. Burning waste materials, including non-recyclable plastics and municipal solid waste, does produce energy, but it also emits a high level of CO₂ and other pollutants, making this process a questionable renewable option.

When municipal solid waste is burned, it releases CO₂ along with other harmful pollutants such as sulphur dioxide, nitrogen oxides, and particulate matter, which contribute to air pollution. Moreover, when plastics derived from fossil fuels are incinerated, they release carbon that has been stored for millions of years back into the atmosphere, negating any “renewable” benefit. In many cases, this form of biomass generation produces higher CO₂ emissions per kilowatt-hour than coal plants.


Biomass Plants and the Risk of Greenwashing
Using waste incineration to produce electricity is an example of greenwashing, where the practice is marketed as green energy despite a negative environmental impact. Biomass plants burning municipal solid waste are often classified as “renewable” under the UK’s ROC scheme, allowing them to benefit from subsidies meant for genuinely low-carbon technologies. This classification not only skews the renewable energy mix but also risks misleading the public and policymakers into believing the grid is greener than it actually is.

While some biomass power plants use sustainably sourced wood and agricultural waste, the fact that waste incineration is allowed under the same classification complicates the picture. Emissions from these plants are not fully offset by the carbon absorption during the biomass growth phase, particularly for waste materials like plastics that never absorbed carbon from the atmosphere to begin with.


Are Biomass Emissions Really Lower Than Coal?
The carbon intensity of biomass plants that use waste incineration can exceed that of coal. Coal emits approximately 820 grams of CO₂ per kilowatt-hour, while some waste incineration plants emit over 1,000 grams of CO₂ per kilowatt-hour. This is due to the lower energy density of waste materials compared to coal, requiring more fuel to produce the same amount of electricity. Additionally, burning waste often releases methane and nitrous oxide, potent greenhouse gases that contribute significantly to global warming.

Given these emission levels, the environmental benefit of biomass-generated electricity—particularly from waste incineration—becomes highly questionable. Many argue that this practice is counterproductive to the UK’s climate goals and risks prolonging dependency on high-emission energy sources.


Rethinking Biomass in the UK Energy Mix
To ensure that biofuels contribute positively to the UK’s carbon reduction efforts, stricter regulations may be necessary. One approach could involve more rigorous classification criteria for what qualifies as renewable biomass. Only biofuels that can demonstrate a net carbon reduction compared to fossil fuels should qualify for government incentives.

Additionally, policies encouraging the use of sustainably sourced biomass, such as locally grown wood pellets, agricultural residues, and manure, could help reduce the carbon footprint of biofuel energy production. Establishing a life-cycle assessment for each type of biomass used in power generation can ensure transparency about its true environmental impact. Finally, transitioning from waste-to-energy practices to more robust recycling and waste reduction strategies could further decarbonize the grid.

Biofuels, when sourced and managed sustainably, can play a role in decarbonizing the UK’s grid. However, the inclusion of waste incineration as a “renewable” biofuel undermines the UK’s carbon reduction efforts, potentially resulting in higher emissions than coal. Without clearer regulations and a commitment to transparency, biomass energy risks becoming a greenwashing tool rather than a genuine solution for climate action. For the UK to reach its net-zero goals, it’s time to critically assess what qualifies as renewable energy and ensure that biofuels truly contribute to a cleaner, greener future.

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