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CCS Versus Carbon-Negative Bioenergy with Biochar

By John Bonitz | August 31, 2011

John Bonitz wrote this letter in response to an article that appeared earlier on the magazine website, and is published in this magazine on page 15. With debate raging over the carbon neutrality of bioenergy, America should embrace biomass technologies that are actually carbon negative. Thus, I applaud the article on the recent IEA Greenhouse Gas study, “Coupling with CCS.”

Thank you for jump-starting the conversation. Beyond this, the study has limited usefulness in the U.S., as policymakers and investors have already largely rejected carbon capture and sequestration (CCS). July’s cancellation of the Mountaineer coal-fired CCS project prompted Businessweek magazine to report, "Five largescale CCS projects have been canceled or postponed, while the fate of several others remains doubtful." In a policy regime where the costs of carbon pollution remain externalized, CCS projects fail due to complexity, high operational costs, large scale and high capital costs.

Current CCS technologies—often called "clean coal"—require 10 to 40 percent more energy input for the same output of a non- CCS power plant. If CCS with energy-dense coal is expensive, then CCS with low-energy density biomass will be even more expensive.

In contrast, the other carbon-negative bioenergy pathway— pyrolysis or gasification with coproduction of biochar—is less complex, can be built at smaller scales, and is less capital intensive. Biofuels and/or biopower are produced while also creating biochar for use as a soil amendment. Any “energy losses” perceived in the conversion of potential Btu into charred carbon is a justifiable form of tithing back to the earth. Afterall, this biochar puts stable, recalcitrant carbon back in the soil, where it has many beneficial impacts.

CCS has ready markets for CO2 pumped underground to enhance oil recovery (EOR). But biomass is a distributed resource, oil wells are not, and there is little biomass in oil country—inherently limiting the EOR market.

Soil scientists are finding biochar has many benefits, including increased crop yields, retention of nutrients and water, and suppression of greenhouse gas emissions.

Granted, until Americans put a price on carbon, both CCS and thermochemical bioenergy are precommercial technologies. Also, additional research is needed to determine the precise benefits of different types of biochar in different soils, for different crops. But investors and policymakers with limited capital might ask themselves, which is a better investment: complex, centralized engineering monoliths or heat-treating biomass for distributed energy and beneficial biochar?

Carbon-negative bioenergy with biochar is a pathway to rebuild the soil, provide for the needs of future generations and provide some of today’s energy needs, while helping to mitigate climate change.

Either way, let’s stop dithering over debatable carbon accounting and take actions that prove their merits with measurable physical sequestration of multibenefit biogenic carbon.

Author: John Bonitz
Southern Alliance for Clean Energy
Bonitz@cleanenergy.org