According to the latest US Greenhouse Gas Inventory Report, electricity generation is the largest contributor to greenhouse gas emissions, accounting for 30 % of the total. On a global basis according to the Intergovernmental Panel on Climate Change (IPCC), carbon dioxide emitted from fossil fuel and industrial processes is the largest contributor, accounting for 65 % of all GHG emissions. It’s no wonder then that a considerable amount of research and development is spent on capturing the carbon dioxide resulting from the combustion of fossil fuels used for electricity generation and other industrial processes such as cement manufacture.
Most of these processes involve contacting the combustion gases, also known as flue gases, with a solvent to absorb the CO2 so when the scrubbed flue gases are eventually released to the atmosphere, they are essentially CO2 free. Such carbon capture processes are known as post-combustion. There are many types of solvents and/or reactants that are effective in capturing most or all of the CO2. The most common systems utilize some type of amine-based chemical, such as mono-ethanol amine (MEA) to absorb the CO2 from the combustion gases. A subsequent step is then employed to release the CO2 and recycle the lean solvent/reagent back to the absorption step.
Additional capital investment is required to install the necessary hardware. There is as well a significant increase in energy usage required to strip the CO2 from the solvent/reagent so it can be recycled to the absorption step. Considerable amount of research has gone into identifying and testing various solvents/reactants that maximize the capture of CO2 from the combustion gases and also minimize the energy required to release the CO2 from the solvent/reagent.
One of these processes is currently being tested at the Technology Center in Mongstad, Norway (TCM,) which is the world’s largest facility for testing and improving CO2 capture technology. TCM was established in 2012 as a joint venture among the Norwegian State, represented by Gassnova (75.12%), Statoil (20.0%), Shell (2.44%) and Sasol (2.44%). Recently it was announced that Gassnova, Statoil, Shell and Total (replacing Sasol) wish to participate in continuation of test operations through 2020.
The carbon capture process being tested is US-based ION Engineering’s proprietary solvent system. Their system is based on research by Dr. Jason E. Bara of the University of Alabama who received several patents based on the use of imidazole containing systems and imido-acid salts. Imidazole, with a chemical formula of C3N2H4, has the following structure:
and is a white or colorless solid soluble in water producing a mildly alkaline solution.
According to the patents, (8,506,914 and 8,673,956), imido-acid salts with an anionic group attached have the same effectiveness as imidazoles, can capture the same or more CO2 than MEA systems, but with correspondingly much less energy required for the regeneration step.
The University of Alabama licensed its patents to Ion Engineering to further develop the technology as a commercial alternative for carbon capture. Based on a grant from the Department of Energy, the technology was originally tested in a small pilot plant at the DOE funded National Carbon Capture Center in Alabama. Success at this stage led to the current testing at TCM, funded through a $7.6 million award from the DOE plus a $6.7 million cost share provided by TCM.
The TCM test site, which is part of Statoil’s Mongstad Refinery has two sources of flue gases; one from a gas turbine power plant with CO2 content at 3.5 %; the other from the refinery’s catalytic cracking unit with CO2 at 13.5 %. There is flexibility to dilute and/or enrich the CO2 content to simulate flue gases from both coal and natural gas-fired power plants; typically at 14% and 3.0% respectively. Two existing gas treating units are available, each approximately 12 MWe in size. Total amount of available CO2 that can be captured is equivalent to 100,000 metric tons/yr. For reference, a 500 MW coal-fired power plant generates around 3.5 million tons/yr of CO2, with a gas-fired power plant emitting around 45% of that amount.
Regardless of whether Ion Engineering’s carbon capture technology is successfully commercialized, this is really only one half of the whole carbon emissions issue. Something must be done with the captured CO2 so that it is not released to the atmosphere. A popular option, part of the Carbon Capture and Storage (CCS) www.ccsassociation.org technology protocol, is transporting the captured CO2 and storing it underground in depleted oil and gas fields or deep salt caverns. The CO2 can also be utilized for enhanced oil recovery (EOR) operations. Another option is to convert the CO2 into a non-emitting product. See my June 3, 2016 blog (Three Carbon Dioxide Utilization Technologies) for a description of three such CO2 conversion processes being developed.
In February of this year the Department of Energy’s Fossil Fuel Division announced funding of $5.9 million to be divided among seven novel CO2 utilization technologies. Each project has to cost share at least 20%. According to the announcement:
“The seven funded project fall under three technical areas of interest: (1) biological-based concepts for beneficial use of CO2, (2) mineralization concepts utilizing CO2 with industrial wastes, and (3) novel physical and chemical processes for beneficial use of CO2.”
Click on the following link for the Feb. 22, 2017 news release with a brief description of each of the seven projects.
As all of these projects are at a very early stage of development, it is unlikely to see any commercial applications any time soon. And under the current mood of the US Government regarding climate change, it may be highly unlikely that any additional funding will be available should any of these technologies show promise for effectively and economically reducing carbon dioxide emissions.