How green of a fuel is Biomass?

The conversion to biomass energy has played a key role in reducing our dependence on fossil fuels across the world. But is this renewable energy source really as green as some claim?

Biomass is derived from organic material such as trees, plants, and agricultural and urban waste. The energy from these materials can be transformed into usable energy through direct and indirect means. Biomass can be burned to create heat (direct), converted into electricity (direct), or processed into biofuel (indirect).

Plans to burn more wood to generate renewable electricity has recently come under fire from environmental groups and sustainable investment campaigners over the controversial claim that biomass energy is carbon-neutral. Carbon-neutrality is allegedly reached when trees absorb as much carbon dioxide when they grow as they emit when they are burnt. Capturing the carbon emissions from biomass power plants would then effectively create “negative carbon emissions”. But wood bioenergy can only reduce atmospheric CO2 gradually over time, and only if harvesting the wood to supply the biofuel induces additional growth of the forests that would not have occurred otherwise.

Burning more imported wood pellets could in fact have the opposite effect and accelerate the climate crisis, lead to an increase in emissions due to long-distance transport, cause biodiversity loss in the habitats where the materials are harvested, and threaten Indigenous people’s land rights in exporting countries such as US and Canada.

In other words, claiming that burning trees is sustainable just because an equivalent quantity of carbon is going to be absorbed somewhere, sometime in the future by the regrowth, is questionable. If biomass feedstocks are not replenished as quickly as they are used, they can become non-renewable. A forest, for instance, can take hundreds of years to re-establish itself. In addition, most biomass requires arable land to develop. This means that land used for biofuel crops such as corn and soybeans are unavailable to grow food or provide natural habitats.

It is also important to note that forested areas that have matured for decades are able to sequester more carbon than newly planted areas. Therefore, if forested areas are not sustainably cut, re-planted, and given time to grow and sequester carbon, the advantages of using the wood for fuel are not offset by the trees’ regrowth.

Looking at its physical properties, biomass has a lower energy density than fossil fuels. As much as 50% of biomass is water, which is lost in the energy conversion process, making it a rather inefficient fuel, not best suited for long-distance transport. On the bright side, unlike other renewable energy sources, such as wind or solar, its energy is naturally stored within the organism, and can be harvested when needed. Burning waste (e.g. waste wood) is seen as a particularly sustainable practice, as this kind of biomass would anyhow slowly release CO2 via natural decay if not burned.

Burning biomass still releases carbon monoxide, carbon dioxide, nitrogen oxides, and other pollutants and particulates. If these pollutants are not captured and recycled, burning biomass can create smog and even exceed the number of pollutants released by fossil fuels. However, we believe biomass could play an important role in reaching climate targets, but only with strict safeguards in place to ensure its sustainability.

How do we evaluate a fuel's degree of sustainability? And how do we deal with biomass sustainability requirements at Uniper?

"In the EU, the Renewable Energy Directive (RED) defines specific criteria to evaluate which types of biomass bring the most benefits from a climate and environmental perspective. The conversion into biofuels of certain types of biomass, such as organic bio-waste, manure, sludge and others is highly recommended as part of a circular economy approach, to have zero waste in our cities  and communities. For example, used cooking oil can be transformed into biodiesel", explains Giangiacomo Dandrea, VP ESG Risk and Business Coordination at Uniper, "Many NGOs are pushing to stop subsidizing solid biomass for electricity production, while the industry is strengthening and improving certification standards to demonstrate compliance with the RED requirements."

Since 2021, the EU Taxonomy on Sustainable Finance has included as potentially sustainable certain business activities related to bioenergy (e.g. solid, liquid and gaseous biofuels), provided that they meet various technical criteria. And the list could soon become longer. But the core principle is that only the most advanced and efficient bioenergy Power or Combined Heat and Power (CHP) plants will be considered sustainable. For example, a biomass plant must demonstrate at least 80% lower greenhouse gas emissions compared to fossil fuels. At the same time the biomass needs to be originated from responsible sources (as per RED) and the local air emissions need to stay below established limits.

At Uniper, bioenergy can and will play a significant role to decarbonize some of our existing assets and also meet the needs for reliable heat and power production for certain industrial customers, provided that they meet the applicable sustainability criteria. From a biomass supply perspective, this means that activities are always aligned with the EU and national rules for sustainable biomass, by sourcing only certified biomass within a certain maximum distance.