Storing and Recycling CO2:  Lots of Ways to Do It with Biomass

Increasing storage and recycling of CO2 are among the critical imperatives if the climate is to be stabilized to a state that is beneficial for continued human development. There are many ways of doing this. We review a few them here.

Of course, the best way to stabilize the climate is to leave the remaining fossil fuels in the ground and reverse the loss of carbon stored in plants and soils that is occurring around the planet today. We are still working on that.

In the meantime, what are some of the ways we can capture, store, and recycle some of that excess CO2 with biomass? Four ideas have been in the news recently.

On November 28, Science Daily reported on the start of the first large scale injection of CO2 emissions from an ethanol plant deep underground for permanent storage. The experimental project will store one million tons of CO2 more than a mile deep in sandstone formations underneath Decatur, Illinois. The project is sponsored by the Department of Energy.

However, geologic sequestration is very expensive and still in the experimental stages. What else can be done now?

The Minneapolis StarTribune reported recently on a project at a Green Plains Renewable Energy plant in Iowa to recycle CO2 from its ethanol plants to produce algae. The algae will be processed into livestock feed, biofuels, or food and nutritional supplements. Although this does not permanently remove CO2 from the atmosphere, it recycles it in the production of additional bio-based products, thereby avoiding additional CO2 emissions. Green Plains plans eventually to install this technology at all nine of its ethanol refineries.

That still seems rather exotic and distant for those of us who live far away from Midwest corn fields. Is there something we could do to store carbon closer to home?

One method is to use more wood in the construction of buildings and products, and then use the residues for bioenergy. That is one of the recommendations in a recent study from the University of Washington “Carbon mitigation strategy uses wood for buildings first, bioenergy second” . When wood is used in building materials, the CO2 captured by the trees is sequestered for the life of the building – often spanning many decades. When wood is substituted for fossil fuel-intensive building materials like concrete and steel, even greater CO2 reductions are achieved. Finally, using the residues from the timber industry to produce biofuels can reduce emissions from fossil fuel and advance energy security. According to a press release: “ ‘When it comes to keeping carbon dioxide out of the atmosphere, it makes more sense to use trees to recycle as much carbon as we can and offset the burning of fossil fuel than it does to store carbon in standing forests and continuing burning fossil fuels,’ said Bruce Lippke, University of Washington professor emeritus of forest resources, one of the eight co-authors. . . The co-authors aren’t advocating that all forests be harvested, just the ones designated to help counter carbon dioxide in the atmosphere. Older forests, for instance, provide ecological values even though they absorb less carbon dioxide as they age.”

Finally, CO2 storage can be achieved by conserving and restoring more wetlands, grasslands, and forests. On December 5, the Department of the Interior released its first regional study evaluating the amount of carbon absorbed by wetlands, grasslands, and forests across the U.S. This study focuses on the Great Plains Region and finds that the region is a net carbon sink – soaking up more CO2 than it emits. The Department will release studies of additional regions in the months ahead.