By Tom Frantz
In the fight against global warming, there is a pressing need to take carbon dioxide (CO2) out of the air and put it into the ground. Reducing greenhouse gas (GHG) emission rates alone is not enough because the atmosphere is already too full of global warming gases. Emission rates not only have to decrease to close to zero but existing GHG levels in the air must be reduced at some point. It is similar to a bathtub running over. Some of the water needs to be removed. Adding more water, even at a drip, will only make things worse.
The California Air Resources Board (CARB) is currently holding workshops on various proposals for carbon capture and sequestration (CCS). Unfortunately, the bulk of their work concerns reducing emissions of CO2 from fossil fuel electrical generation. They are also considering the use of biomass for renewable energy and then capturing the CO2 emissions to theoretically reduce atmospheric CO2 levels. For several reasons, neither of these two ideas are going to get us to zero emissions, let alone lowered levels of atmospheric GHG.
Meanwhile, there is a third method of carbon capture and sequestration which is a viable solution. Basically, growing plants and returning all possible biomass directly to the soil can provide net reductions in atmospheric CO2 by building up carbon stored in soil. Even today, with carbon depleted soils around the world due to industrial farming and deforestation, there is three times as much carbon in soil than in the atmosphere. This idea is being promoted vaguely by CARB and Governor Brown but it needs more than just talk and lofty goals. Increasing soil carbon is a true and simple solution to the overflowing bathtub scenario.
Not counting increasing soil carbon, most proposals for CCS involve gasification of the fuel, fossil or otherwise, and separating the gases into CO2 and dirty forms of hydrogen. The CO2 can be used very effectively for enhanced oil recovery (EOR). The CO2 can also be injected into a saline layer deep in the ground and protected from leakage to the surface by a harder shale layer above.
The idea of CCS and subsequent EOR is promoted heavily by the oil industry as a climate solution. The dirty hydrogen gases can be burned in a boiler just like methane but with far fewer CO2 emissions. But, air pollution such as NOx and particulates from burning this gas is worse than burning clean natural gas.
One problem with CCS from fossil fuels is not all of the CO2 can be captured so it is not zero emission technology. It is also a very energy intensive process to gasify the fuel and separate the gases. This decreases significantly, compared to conventional power plants, the amount of energy available to the grid. Also, when the CO2 is injected for EOR in older oil fields, there is also a lot of potential leakage.
Not only are these oil fields full of disintegrating wells that can allow leaks to the surface, but most of the injected CO2 comes up with the recovered oil and must be recaptured, cleaned, pressurized, and reinjected multiple times until further oil production ceases and the CO2 finally becomes “sequestered”. Ironically, the CO2 injection recovers oil not available through other means. This surplus oil gives off massive amounts of new CO2 when it is consumed and helps to stimulate consumption by increasing supply. This is not a way to reduce CO2 in the atmosphere or even put a dent in our current rate of emissions.
Combining biomass as a fuel with CCS looks superficially attractive since new trees and plants regrow in the place of the ones consumed and the new plant growth absorbs CO2 from the air. If the CO2 released by combustion is captured and put into the ground, an over simplified equation shows this process is carbon negative. But, the process is much more complicated. Consider the following points.
One, there will never be enough biomass economically available to provide more than 2% of our electrical energy needs. The amount of energy absorbed by plants is a fraction of the energy consumed by humans. Also, surplus agricultural biomass is an oxymoron. All of this carbon based material should be returned to the soil for the growing of future crops and for enriching the productivity of the soil.
Building up the carbon levels in soil is a much more efficient way to sequester carbon than gathering, hauling and burning good, clean biomass at a power plant and subsequently capturing some of the CO2 emissions for injection deep into the ground. There is also no way to economically remove even a fraction of the biomass from our forests in order to make energy. Besides, removing forest biomass ultimately depletes the carbon in the forest soil slowing down future growth and leaving no net reductions from the artificial and partial sequestration.
Second, burning biomass, even with esoteric methods such as gasification, is inefficient in terms of energy production and extremely dirty in terms of local air pollution. No one will propose these plants for cities so places like the San Joaquin Valley get the biomass trucked from the forests and urban landfills for local incineration and it increases our air pollution levels.
Finally, there is also a push to increase burning biomass and perhaps garbage for energy even without CCS since it is described as a carbon neutral process. But, burning biomass releases massive amounts of CO2 into the air. This CO2 will theoretically be absorbed by growing plants over the next fifty to one hundred years. However, because of inefficiencies, the rate of CO2 emissions from biomass per megawatt hour of electricity is far greater than from the natural gas plant being replaced. It should be obvious the planet cannot afford to increase atmospheric CO2 right now while waiting dozens of years for CO2 levels to slowly decrease while new trees grow in the forest.
There is also talk of capturing and sequestering CO2 from the fermentation process at ethanol plants. The idea is this would produce ethanol with a much lower carbon footprint. Unfortunately, this keeps our internal combustion engines going forever and thereby keeps hope alive in the oil industry that their fossil fuel will continue to be useful. The moral issue with ethanol from plants is can the United States continue to grow food for fuel and subsequently build a wall to keep the masses of a starving world at bay.
Longtime clean air advocate Tom Frantz is a retired math teacher and Kern County almond farmer. A founding member of the Central Valley Air Quality Coalition, he serves on the CVAQ steering committee and as president of the Association of Irritated Residents. CVAQ is a partnership of more than 70 community, medical, public health, environmental, and environmental justice organizations representing thousands of residents in the San Joaquin Valley unified in their commitment to improving the health of Californians. For more information, visit www. calcleanair.org.