Biomass energy is power derived from organic materials, primarily plants and animal waste, that can be burned directly for heat or converted into liquid and gaseous fuels. It is one of the oldest energy sources humans have used and remains a significant part of the renewable energy landscape today. Unlike fossil fuels, which take millions of years to form, biomass can be regrown within a human lifetime, making it technically renewable.
Where Biomass Comes From
The raw materials for biomass energy fall into four broad categories. Wood and wood processing waste make up the largest share: firewood, wood pellets, wood chips, sawdust from lumber and furniture mills, and a byproduct called black liquor from pulp and paper manufacturing. Agricultural crops and their residues form the second category, including corn, soybeans, sugarcane, switchgrass, and algae, most of which go toward producing liquid biofuels. Municipal solid waste contributes a third stream, specifically the organic fraction: paper products, cotton and wool textiles, and food, yard, and wood scraps. Finally, animal manure and human sewage can be broken down by bacteria to produce biogas, a renewable form of natural gas.
Three Generations of Feedstock
Researchers classify biomass feedstocks by generation. First-generation feedstocks are food crops like corn, sugar, and vegetable oil. They’re the easiest to convert into fuel but come with a significant trade-off: using edible crops for energy raises food prices and competes for farmland. Second-generation feedstocks sidestep that problem by using non-food plant material, things like forestry residues, crop stalks, and wood waste. These are harder to break down chemically but don’t pull food off the table. Third-generation feedstocks are algae, which can be cultivated in water and don’t require arable land at all, though large-scale algae-based fuel production is still in early stages.
How Biomass Becomes Energy
There are two main pathways for turning organic matter into usable energy: thermochemical and biochemical.
Thermochemical methods use heat. The simplest is direct combustion, burning wood or waste to produce heat or steam that drives a turbine. Gasification heats biomass at very high temperatures to break it down into a gas mixture called syngas, which can then be burned in engines or turbines or further refined into liquid fuels. Pyrolysis heats biomass in the absence of oxygen, producing a crude bio-oil along with gases and a solid charcoal-like residue. Liquefaction uses moderate heat and high pressure, often with water, to break biomass into smaller chemical fragments that recombine into new liquid compounds.
Biochemical methods rely on microorganisms. Anaerobic digestion uses bacteria to decompose organic waste (food scraps, manure, sewage) in the absence of oxygen, producing methane-rich biogas. Fermentation uses yeast or other microbes to convert sugars and starches into ethanol, the same basic process behind brewing beer, just scaled up for fuel production.
Biofuels: The Liquid Side of Biomass
When biomass is converted into liquid form, the resulting products are called biofuels, and they’re used mostly for transportation. Ethanol dominates the U.S. biofuel market, accounting for 82% of domestic biofuel production in 2022. It’s blended with gasoline (the “E10” or “E15” labels at the pump mean 10% or 15% ethanol). Biodiesel, made from vegetable oils or animal fats, represented about 9% of production and is typically blended with petroleum diesel. Renewable diesel, a newer product that is chemically identical to petroleum diesel and can replace it directly, made up roughly 8% of production.
Beyond those three, a growing list of biofuel products includes renewable jet fuel (often called sustainable aviation fuel), renewable heating oil, and renewable gasoline, all at various stages of commercialization.
The Carbon Neutrality Question
Biomass is often described as carbon-neutral, and the logic is straightforward: the plants used as feedstock absorb CO2 from the atmosphere as they grow, and burning them releases roughly the same amount back. In theory, it’s a closed loop. Fossil fuels, by contrast, release carbon that has been locked underground for millions of years, adding new CO2 to the atmosphere on a net basis.
In practice, the picture is more complicated. Growing, harvesting, and transporting biomass all consume energy, often from fossil fuels. Burning municipal solid waste emits about 1.3 tons of CO2 equivalent per ton incinerated, comparable to petroleum-based power plants. And if forests are cleared to grow energy crops, the carbon stored in those trees is released immediately while new plantings take decades to reabsorb it. This delay is sometimes called “carbon debt.” So while biomass can reduce net emissions compared to fossil fuels, calling it perfectly carbon-neutral oversimplifies the math.
One clear win: capturing methane from manure or landfills and burning it for energy. Methane is a far more potent greenhouse gas than CO2, so converting it to CO2 through combustion actually lowers the overall warming effect, even though combustion still releases carbon.
Bioenergy With Carbon Capture
A technology called BECCS (bioenergy with carbon capture and storage) aims to make biomass energy not just carbon-neutral but carbon-negative. The concept has three steps: grow biomass that absorbs CO2, burn it to generate electricity, then capture the CO2 from the exhaust and store it underground instead of releasing it. The result, in theory, is energy production that actively removes carbon from the atmosphere.
Current capture technology can grab 85% to 95% of the CO2 produced during combustion, depending on the method used. The Intergovernmental Panel on Climate Change considers BECCS essential to meeting global warming targets. In its modeling, 87% of scenarios that keep warming below 2 degrees Celsius include large-scale BECCS deployment. However, the technology faces real hurdles: it works best when biomass sources and storage sites are close together, it requires significant transportation infrastructure, and underground CO2 injection carries concerns about induced seismic activity.
Water and Land Constraints
Biomass energy requires substantial natural resources beyond the organic material itself. Agricultural production already consumes roughly 86% of global freshwater use for food and fiber. Scaling up biomass for energy adds pressure to an already strained system.
Water intensity varies enormously depending on the crop and the end product. For generating electricity, sugarcane, sugar beet, and corn are the most water-efficient options, requiring around 50 cubic meters of water per gigajoule of energy. Rapeseed and jatropha are far thirstier at 400 cubic meters per gigajoule. For ethanol production, sugar beet and potato perform best (60 to 100 cubic meters per gigajoule), while sorghum requires about 400. To put it in more tangible terms, producing a single liter of biofuel can require anywhere from 1,400 to 20,000 liters of water.
One practical insight from the research: using whole biomass for electricity or heat is more water-efficient than converting only a fraction of a crop (its sugar, starch, or oil) into liquid biofuel. This is because electricity generation uses the entire plant, while biofuel production discards much of it.
Cost of Biomass Power
The U.S. Energy Information Administration projects the levelized cost of new biomass power plants entering service in 2030 at roughly $53 to $59 per megawatt-hour in 2024 dollars. Levelized cost accounts for construction, fuel, maintenance, and financing over a plant’s lifetime, making it a useful apples-to-apples comparison across energy sources. Biomass falls in a middle range: cheaper than some fossil fuel options with carbon capture but generally more expensive than utility-scale solar or onshore wind, which have dropped dramatically in recent years.
The economics of biomass depend heavily on local conditions. A sawmill with mountains of wood waste can produce heat and power cheaply because the fuel is essentially free. A facility that needs to grow, harvest, and truck in dedicated energy crops faces much higher costs. Proximity to feedstock is one of the single biggest factors determining whether a biomass project pencils out financially.