Biomass offers great energy potential

Most of what I write in this space is about innovations in electric generation and storage, because that’s where the biggest market changes are happening.

Innovations that will increase the use of renewable energy are also happening for liquid and gas fuels. Renewable liquid and gas fuels are derived from “biomass,” which is exactly what it sounds like: biologically derived matter. Plant materials (agricultural wastes, waste paper, purpose-grown crops) and animal-related waste materials can all be converted into a variety of fuels.

Biologically derived fuels can be used directly for heat, such as burning wood in a fireplace.

Renewable natural gas can be produced by processing manure and other animal byproducts in a digester. Farmers in countries with limited power infrastructure have long used this technique to produce natural gas for home electric generators and for water heating.

Biomass can be converted into electric energy, via gasification that produces a fuel that can be used in a generator, or via direct combustion to produce heat to boil water and run a generation turbine. Significant work is underway to improve the flexibility, scale, cost and accessibility of technologies like digesters and gasifiers. Research is also underway to develop new techniques to use biomass in various types of electrical generation and heating equipment. Some of these innovations are starting to gain commercial traction, e.g., small-scale machines that can convert shipboard wastes to heat or electricity, thus reducing the need for fossil fuels and reducing the long-standing process of throwing garbage overboard.

Liquid fuels can be produced through fermentation (e.g., of corn or sugar cane) to produce ethanol. Biomass like vegetable oil waste from restaurants can also be converted into biodiesel and used in trucks.

As I mentioned a few weeks ago in a column about aircraft, it’s even possible to combine renewable electricity, water and a source of carbon to synthesize highly refined products like gasoline, diesel or jet fuel. These products don’t have to be derived from petroleum – they can be manufactured, and they can even be renewable if the sources of carbon and electricity are renewable. They can be used as direct substitutes for conventional fuels. The U.S. Air Force has proven that such fuels work in fighter jets.

Wood chips, corn stover, leaves and similar plant-based waste products from crops that are already being grown can offer farmers a potential new source of revenue, if the infrastructure is developed to use these waste materials as energy. A more controversial idea, since it has the potential to put food crops into competition with energy crops, is to grow biomass crops. Specific fast-growing crops, like switchgrass, can be harvested annually and converted into energy. If the land used for energy crops would otherwise not be used for food crops, this potential conflict isn’t relevant.

Biomass as a renewable energy source is intended to be carbon neutral. When biomass is burned, it releases carbon dioxide into the atmosphere, just like fossil fuels. However, the difference is that the carbon released during the combustion of biomass was recently absorbed by plants through photosynthesis.

If the cycle is maintained, i.e., if the biomass is replenished, biomass can theoretically release no new net carbon emissions. However, for biomass to be truly sustainable, the rate of biomass production has to match or exceed the rate of consumption.