Because hydromethanation is a catalytic process that does not rely on combustion, it does not produce the nitrogen oxide (NOx), sulphur oxide (SOx) and particulate emissions typically associated with the burning of carbon feedstock. Instead, the process captures nearly all of the impurities found in coal, petroleum coke and biomass and converts them into valuable chemical-grade byproducts.
Ash, sulfur, nitrogen, and trace metals are all removed using industry standard gas clean-up processes and are either safely disposed of or used as raw materials for other products. For example, sulfur is converted to elemental sulfur or sulfuric acid, nitrogen is converted to fertilizer-quality ammonia, and mineral matter can be used as road bed material or as a component in activated carbon. GreatPoint Energy believes it is critical and environmentally responsible to make full use of all products and continues to investigate new value-added uses for the materials it produces.
When bluegas™ pipeline quality natural gas is used to supply a power plant, criteria pollutant emissions are significantly less than those from other coal combustion technologies, even with post-combustion emissions control technology, and are on a par with new natural gas combined cycle power plants as illustrated in the chart below.
In addition to this superior emissions profile for criteria pollutants, hydromethanation emits far less mercury than other coal combustion technologies such as old coal plants or integrated gasification, combined-cycle facilities. In order to meet all pipeline specifications in the production of bluegas™ natural gas, mercury is removed by an additional step that is not typically employed in other coal conversion processes, ensuring nearly all of this harmful pollutant is kept from being introduced into the atmosphere.