Dear EarthTalk:

Why hasn’t biomass caught on more as a renewable energy source?

PJ, via email

Biomass is organic material derived from living or recently living organisms like plants, animals and microorganisms. It can be used as a renewable energy source via combustion, fermentation or conversion to biofuels. Some biomass sources, like oil or alcohol-rich crop residue and animal manure, are widely produced on an industrial scale. As we deplete and intentionally shift away from the pollutive natural gas, oil and coal, optimists believe that biofuel may become a viable widespread renewable alternative.   

First-generation biofuels use food crops, like corn and sugarcane, but this diverts resources from food production. Instead, second-generation biofuel uses inedible biomass, like wood and agricultural waste. These are low-cost and can serve also to reduce waste, as they use animal and plant waste that would otherwise go to landfills. The U.S. Department of Energy says using up to a billion tons of biomass each year for biofuel could reduce petroleum consumption by 30 percent and create new domestic jobs.

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Biomass proponents call biofuel carbon neutral because the carbon dioxide (CO2) released during its combustion is offset by the amount that is absorbed by the plants during growth. Others believe this overlooks factors like land use change, biomass processing emissions, and the methane released during decomposition. Biomass combustion also releases carbon monoxide, nitrogen oxides and particulate matter, highlighting the environmental and health risks associated with biomass utilization.

It takes decades for biomass-produced carbon to be removed from the atmosphere. Studies suggest that it may even be a dirtier business than fossil fuels, with wood and corn-based ethanol emitting from 1.25 to 1.5 times more CO2 than coal per kilowatt-hour of electricity generated. Research conducted by Harvard's Jonathan Buonocore suggests that biomass combustion causes more health-related deaths than conventional coal-fired power plants. Moreover, biomass production can contribute to loss of forests and biodiversity, and indirect land use change. Burning biomass can cause significant public health issues, including asthma, heart and respiratory diseases, birth defects, and even death.

Mitigating environmental and health drawbacks and enhancing the effectiveness of current technologies can help make biofuel more viable. Investing in advanced biomass conversion technologies, such as gasification and pyrolysis, can reduce greenhouse gas and toxic byproducts during combustion. Promoting sustainable sourcing practices, including the exclusive use of agricultural and forestry residues rather than dedicated energy crops, can minimize deforestation and habitat destruction.

Biofuels today are more expensive than conventional fuels like natural gas and crude oil. Researchers aim to design processes that better utilize lignin and sugars in biomass. If this can be achieved, biomass-derived aviation fuel could potentially achieve a break-even price as low as $3.15 per gallon of gasoline-equivalent, offering a competitive edge against traditional jet fuel costs. If we can address these health, environmental and technological challenges, we may well realize the full potential of biofuels.

CONTACTS

• Health consequences of using biomass for energy, https://www.hsph.harvard.edu/news/hsph-in-the-news/health-consequences-of-using-biomass-for-energy/
• Biomass Energy: Climate Solution or Potential Catastrophe? https://kleinmanenergy.upenn.edu/news-insights/biomass-energy-climate-solution-or-potential-catastrophe/
• Inexpensive, carbon-neutral biofuels are finally possible, https://www.sciencedaily.com/releases/2024/02/240207120424.htm.

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