The heart of the bluegas™ technology is catalytic hydromethanation, an elegant process by which carbon-rich feedstocks – such as coal, petcoke, and biomass – are converted through a combination of catalytic reactions in the presence of water into a methane-rich gas stream. Figure below illustrates the basic process to produce Substitute Natural Gas (SNG).
The first step in the hydromethantion process is to disperse the catalyst throughout the matrix of a carbon-rich feedstock under specific conditions so as to ensure effective reactivity. The catalyst/feedstock material is then loaded into the hydromethanation reactor. Inside the reactor, pressurized steam is injected to "fluidize" the mixture and ensure constant contact between the catalyst and the carbon particles. In this environment, the catalyst facilitates multiple chemical reactions between the carbon and the steam on the surface of the particles. These reactions (shown below), catalyzed in a single reactor and at the same low temperature, generate a mixture predominately composed of methane and CO2.
The overall combination of reactions (shown below) is thermally neutral, requiring no addition or removal of energy, making it highly efficient.
The proprietary sulfur-tolerant catalyst formulation is made up of abundantly available, low cost metal materials specifically designed to promote gasification at the low temperatures where water-gas shift and methanation reactions concurrently take place. The catalyst is continuously recycled and reused within the process.
By adding this catalyst to the system, GreatPoint Energy is able to reduce the operating temperature in the gasifier while directly promoting the reactions that yield methane. Under these mild "catalytic" conditions, less expensive reactor components can be utilized, pipeline grade methane is produced, and very low-cost carbon sources (such as lignites, sub-bituminous coals, petroleum coke and biomass) can be used as feedstock.
As part of the overall process, the bluegas™ technology enables the recovery of contaminants in coal, petroleum coke and biomass as useful byproducts. In addition, nearly all of the CO2 produced in the process is captured as a pure stream suitable for sequestration or enhanced oil recovery.