Synthetic natural gas is chemically similar to natural gas. Synthetic natural gas may sound like an oxymoron, but it is a valid name, like synthetic fibers which look and feel similar to natural fibers. Substitute Natural Gas is another name for Synthetic Natural Gas. Perhaps Synthetic Methane would be a better name.
Today, the USA has abundant cheap natural gas, but with expanded use for transportation fuel and electricity generation the natural gas supply will need to be supplemented with synthetic or substitute natural gas (SNG).
The USA has enormous natural resources of coal and oil shale. Advanced gasification technology, located directly at the coal mine or oil shale field can be used to gasify the hydrocarbon resource for methanation, producing pipeline quality SNG. The synthetic natural gas would then be sent via pipeline from the mine site to the nation’s electric power plants. Coal would no longer need to be shipped to the electric power plant or burned directly. Carbon capture and sequestration (CCS) of CO2 emitted by the gasification process would be performed on-site at the mine.
Carbon Neutral SNG
After all emissions and waste products produced by the gasification process have been captured and sequestered, SNG will be as clean as natural gas, but as natural gas, SNG is not carbon neutral. Natural gas is primarily methane: CH4. The ‘C’ in the chemical formula for methane represents a carbon atom, the ‘H4’ represents four hydrogen atoms.
If biomass is gasified with the coal, it is possible to make the SNG completely carbon neutral: but only if carbon capture and sequestration (CSS) of the process waste emissions is performed as part of the SNG production. If CSS is performed, and the carbon in the SNG is equal to the carbon in the biomass that has been gasified, then the SNG would be carbon neutral, because all of the coal carbon would be captured and sequestered as part of the cleanup process before the SNG is sent to the pipeline. In other words, the coal would provide the energy for the process and for the hydrogen production required for methanation, and all CO2 emitted by the process and hydrogen production will be sequestered at the mine site.
In this way, carbon-neutral SNG can be delivered to the electric utility plant by pipeline, and thus, the electric utility would not need to be involved with CO2 emission regulations or carbon capture.
The mine site SNG production plant could also produce methanol, and eventually synthetic ethanol as catalysts become available. Carbon neutral SNG would produce carbon-neutral alcohol fuels.
The USA has a large enough coal and oil shale resource base to support SNG production that could fuel U.S. electric generation and transportation for over 100 years. Biomass alone would not be large enough to do this, but biomass (non-food biomass) can be produced in large enough quantity to provide the carbon-neutral ‘C’ in the SNG CH4 allowing coal and oil shale to provide the hydrogen and process energy with carbon capture and sequestration.