A new energy system that harvests energy from urban and agricultural waste and then stores carbon dioxide emissions underground could help California’s electric grid become carbon-negative in the future, according to a recent study by UC Berkeley researchers.
The proposed system would use carbon capture and sequestration, which involves capturing carbon-dioxide emissions from electric power plants, converting them into high-pressure form and storing the substance underground “for several millennia,” according to study leader Daniel Sanchez, a graduate student with UC Berkeley’s Energy and Resources Group.
The study, run out of UC Berkeley’s Renewable and Appropriate Energy Laboratory, is designed in direct response to climate change. Combined with carbon-neutral sources of energy, such as wind and solar, the plan could help California exceed its goal of reducing carbon emissions by 80 percent by 2050.
“The big benefit is that we can (achieve negative carbon emissions),” said campus professor Daniel Kammen, who worked on the study. “(Wind and solar) can go to zero, but they can’t go negative.”
The system would use sustainable energy gained from biomass, a term that includes urban and agricultural waste such as wood from construction sites, corn stalks left in fields and trees thinned from California’s forests, according to the study.
These sustainable fuels — combined with putting carbon dioxide underground, using wind and solar energy and reducing fossil fuels — would create up to a “145 percent emissions reduction from 1990 levels,” according to the study, turning the western Northern American power grid carbon-negative.
In contrast, electric power plants using coal and natural gas could potentially use carbon sequestration, which is rarely used, to capture about 85 percent of carbon-dioxide emissions, thus creating a low-carbon system. Wind and solar energy are carbon-neutral.
“We’re trying to understand how you might operate the electricity grid in the future,” Sanchez said.
The new system would also produce electricity, but its main benefit would be from the carbon storage, according to Sanchez. The system is designed to work with the power grid in certain parts of western North America.
There are still several potential problems, however, with actually putting the system into practice. Biomass wouldn’t be sufficient to run the energy grid alone. Carbon sequestration is largely untested, with limited industrial usage so far.
Additionally, Kammen said it remains to be seen whether the the system is “economically viable.” Companies in Norway and North Dakota have used carbon sequestration.
“We have to see if real companies can do it. If this works, there’s a very exciting story,” Kammen said. “But those ifs are really big ifs.”
The study will be published in the March edition of the scientific journal Nature.
Contact Anna Sturla at [email protected].