A biomass power plant generates electricity by burning organic materials, such as wood, agricultural waste, or municipal garbage, to produce steam that spins a turbine. It works on the same basic principle as a coal plant, but uses renewable or waste-derived fuel instead of fossil fuels. Biomass currently supplies a small but steady share of the world’s electricity, and these plants range from large industrial facilities to smaller community-scale operations.
How Biomass Becomes Electricity
The most common method is direct combustion. Organic fuel is fed into a boiler and burned at high temperatures. The heat turns water into high-pressure steam, which flows over a series of turbine blades and causes them to spin. That spinning turbine drives a generator, which produces electricity that feeds into the grid. If you’ve ever seen how a coal or natural gas plant works, the back half of the process is nearly identical.
Not all biomass plants burn their fuel directly, though. Two other conversion technologies are widely used:
- Gasification heats biomass in an oxygen-starved environment, breaking it down into a synthetic gas (called syngas) rich in carbon monoxide and hydrogen. That syngas can then be burned in a gas turbine, much like natural gas.
- Anaerobic digestion uses bacteria to ferment wet organic matter, like animal manure or food waste, in sealed tanks. The process produces biogas, which is mostly methane and can replace natural gas in turbines or engines.
Some facilities also convert biomass into a liquid bio-oil, which can substitute for diesel or fuel oil in turbines and industrial engines.
What Fuels a Biomass Plant
Biomass plants can run on a surprisingly wide range of organic materials. The U.S. Energy Information Administration groups them into four main categories:
- Wood and wood processing waste: firewood, wood pellets, wood chips, sawdust from lumber and furniture mills, and black liquor (a byproduct of pulp and paper manufacturing).
- Agricultural crops and residues: corn, soybeans, sugar cane, switchgrass, woody plants, algae, and leftover material from crop and food processing.
- Biogenic municipal solid waste: paper products, cotton and wool textiles, and food, yard, and wood scraps pulled from garbage streams.
- Animal manure and sewage: used primarily in anaerobic digesters to produce biogas.
The choice of fuel shapes everything about the plant, from its size to its efficiency to the composition of its ash. A facility burning clean wood chips operates differently than one processing wet municipal waste.
Efficiency Compared to Other Power Plants
Biomass plants are less thermally efficient than large coal or natural gas facilities. A dedicated biomass plant typically converts about 30% to 35% of the energy in its fuel into electricity. High-quality wood chips in a modern plant with optimized steam temperatures can push electrical efficiency to 33% or 34%, and up to 40% in electricity-only mode. Municipal solid waste plants tend to sit lower, around 22%.
One way to boost those numbers is co-firing, where biomass is blended with coal in an existing large-scale coal plant. Co-firing takes advantage of the coal plant’s larger, more efficient boilers and can reach 35% to 45% efficiency. According to the International Energy Agency, co-firing in modern coal plants is currently the most cost-effective way to use biomass for power generation.
For context, a modern natural gas combined-cycle plant typically hits 55% to 60% efficiency, so biomass lags behind fossil fuels on raw thermal performance. The trade-off is the renewable fuel source.
Cost of Biomass Power
Biomass electricity costs more than solar or wind. The EIA’s projections for new plants entering service in 2030 put the levelized cost of biomass power at about $58.54 per megawatt-hour, compared to $37.82 for solar and $29.58 for onshore wind (all in 2024 dollars, including tax credits). Capital costs for dedicated biomass steam plants run between $3,000 and $5,000 per kilowatt of capacity, while co-firing retrofits are cheaper at $1,100 to $1,300 per kilowatt.
Where biomass holds an advantage over wind and solar is dispatchability. A biomass plant can run around the clock and ramp output up or down on demand, while solar and wind depend on weather. That makes biomass useful as a baseload or backup source in grids that need reliable, controllable generation.
Carbon Emissions and the Neutrality Debate
Biomass is often called “carbon neutral” because the plants absorbed CO2 while growing, and burning them simply releases that same carbon back into the atmosphere. In theory, the cycle balances out over time as new plants regrow and reabsorb it.
In practice, the picture is more complicated. Life cycle assessments that account for harvesting, processing, and transporting the fuel find that biomass power does produce measurable emissions. One recent study of an advanced biomass system found a lifecycle global warming impact of about 98 kg of CO2 equivalent per megawatt-hour. That’s far lower than coal (typically 800 to 1,000 kg) but not zero. The same study found that in a co-fired system, net zero carbon emissions are achieved when biomass makes up more than 10% of the fuel mix.
The timeline matters too. Burning a mature tree releases its stored carbon immediately, but regrowing that tree to reabsorb the same amount takes decades. Whether biomass counts as truly carbon neutral depends heavily on what’s being burned, where it comes from, and how fast it regenerates.
What Happens to the Ash
Combustion produces two types of solid residue: bottom ash that collects at the base of the boiler, and fly ash carried upward with the exhaust gases and captured by filters. Rather than going to landfills, biomass ash is increasingly used as an ingredient in cement and concrete. It contains calcium, silicon, aluminum, and iron oxides, the same minerals needed in cement production.
Research published in PMC found that fly ash from wood-chip combustion works particularly well as a cement additive when captured by certain types of filters. The fine, spherical particles improve how the cement mix flows and can enhance the final strength of the hardened material. This gives biomass plants an additional revenue stream while diverting waste from disposal.
Carbon Capture and Biomass
One of the more ambitious applications of biomass power is pairing it with carbon capture and storage, a combination known as BECCS. Because the fuel absorbed CO2 while growing, capturing and permanently burying the emissions from burning it would, in theory, result in net negative emissions: pulling carbon out of the atmosphere rather than just balancing it.
The technology exists but remains small-scale. Only about 2 million tonnes of biogenic CO2 are captured per year globally, mostly from bioethanol production, and less than 1 million tonnes are stored in dedicated geological formations. The largest operating BECCS project is the Illinois Industrial CCS Project, which has been injecting captured CO2 into deep rock formations since 2018. Two more facilities at bioethanol plants in North Dakota came online in 2022 and 2023.
Based on projects currently in development, capture from biogenic sources could reach around 60 million tonnes per year by 2030. That falls well short of the roughly 185 million tonnes per year that the IEA’s Net Zero Emissions scenario calls for by the same date. Denmark, the United Kingdom, and the United States are all actively developing policy frameworks and subsidies to accelerate deployment, but BECCS remains far from mainstream.