Local ag waste prized as fuel source, carbon for storage
To the lingering question of what to do with woody ag waste and other forms of Central Valley biomass, carbon scientists and investors agree on an answer: gasify it, sell some of the byproduct as fuel and bury the leftover carbon deep underground. Doing so would produce a net decrease in greenhouse gas emissions while forestalling pollution from open burning and even preventing groundwater contamination if some of the waste involved is manure. What’s more, the whole process appears to be a moneymaker, thanks to a growing market for both hydrogen and carbon credits. At a symposium on carbon capture and storage Friday at Cal State Bakersfield, great hope was placed in the process, referred to during the inaugural meeting as BiCRS (pronounced “bikers”): bioenergy with carbon removal and storage. Two such projects have been proposed in Kern, but neither has taken more than early steps toward development. Expectations are that considerably more money will be invested as part of a wider push to capture and sequester carbon. Other means include removing it from smokestacks and pulling carbon dioxide straight out of the atmosphere.
Energy Program Chief Scientist Roger Aines at Lawrence Livermore National Laboratory told Friday’s audience BiCRS is a “clear winner” in combined economics and environmental benefit, as long as the biomass used is low-moisture and the carbon is not allowed to return to the atmosphere. If done right, he said, BiCRS results in an overall decrease in greenhouse gas emissions. Aines dismissed the idea of merely burying biomass, as is sometimes done in local almond orchards, because he said it continues to emit methane. He said a better option is injecting it deep underground to keep it there permanently. He noted the process works with everything from almond shells to forest waste. Biomass used to be a greater producer of energy in the Central Valley than it is now. Utilities contracting for cleaner power found that other renewable sources of electricity beat the cost of most biomass plants. Plus, environmental justice groups have targeted them as significant producers of particulate air pollution. Gasification works differently. It does not combust but super-heats waste feedstock to break it down into gases like hydrogen and carbon dioxide. The process puts out much less air pollution.
If the process is used on manure, such as is produced in large quantities at local dairies, it avoids methane emissions and keeps nitrates out of local groundwater, which would reduce risks of cancer, fetal growth retardation and other negative health outcomes, Lawrence Livermore staff scientist Kim Mayfield noted at Friday’s symposium. Still, more research is needed to document the complete and complex carbon lifecycle of BiCRS, said Deputy Director Colin Murphy at the UC Davis Policy Institute for Energy, Environment and the Economy. He emphasized the concept has been greeted with some skepticism by California’s Spanish-speaking communities and others living in agricultural and industrial areas. His recommendation was for better engagement with such communities.
One project proposed in Kern would gasify local ag waste and turn it into hydrogen and carbon dioxide. The latter byproduct would be stored permanently in concrete or injected into a depleted or nearly depleted oil or gas reservoir. Southern California-based Mote says it has begun preparations on a $100 million facility outside Bakersfield that would capture 150,000 metric tons of CO2 yearly starting as soon as 2024. The startup expects to sell hydrogen for use by heavy-duty trucks in the Central Valley. It would also cash in on federal tax credits, revenue from sales of carbon credits and state incentives. Speaking at Friday’s symposium, Mote co-founder and CTO Josh Stolaroff said the project’s economics allow it to gather biomass across a wider radius than conventional biomass power plants. BiCRS is also a relatively large job creator per dollar of investment, he said.
The other BiCRS project that has been disclosed publicly in Kern would work differently. It would produce methane for injection into a local natural gas pipeline for use as transportation fuel. CO2 from the process would be injected underground, while the carbon-rich byproduct biochar could be used in different ways, such as a soil amendment or water filtration or odor-absorber. Frontline Bioenergy LLC, the Iowa-based technology company behind the proposal, wants to build the plant in McFarland and employ about 50 local residents. It has estimated the plant would gasify about 300,000 tons per year of nut shells and other local ag waste and produce the natural gas equivalent of 22 million gallons of gasoline, plus 125 tons per day of biochar.