|The methanation pathway for the production of SNG. Click to enlarge.|
Peabody Energy and ConocoPhillips are exploring the development of a commercial scale coal-to-substitute natural gas (SNG) facility using proprietary ConocoPhillips E-GAS gasifier technology.
The project would be developed as a mine-mouth facility at a location where Peabody has access to large reserves and existing infrastructure. It would be designed to produce 50 billion to 70 billion cubic feet of pipeline quality SNG annually from more than 3.5 million tons of Midwest sourced coal. In addition, presuming there is a supportive regulatory framework in place, the project scope will provide for carbon capture and storage.
There are a variety of production pathways the syngas resulting from coal (or other feedstock, such as biomass) gasification can take. One such is a Fischer-Tropsch pathway for the production of liquid fuels and chemicals. Another is a methanation pathway for the production of SNG. The methanation pathway has the following steps:
Coal gasification to produces a hydrogen- and carbon monoxide-rich syngas;
Shift reaction to adjust the ratio between hydrogen and CO;
Removal of sour gases in a washing process; and
Methanation: the catalytic reaction of carbon oxides and hydrogen to form methane (CH4), followed by drying and compression.
The basic methanation reactions are as follows:
CO + 3H2 → CH4 + H2O
CO2 + 4H2 → CH4 + 2H2O
Some researchers have argued that co-production of liquid fuels and SNG using both F-T and methanation pathways is the most economically efficient.
Peabody and ConocoPhillips would participate in project ownership along with other potential equity partners. The preliminary design and economic assessment is expected to be complete in early 2008.
Natural gas demand has grown rapidly in recent years, and development of coal-to-SNG projects is gaining increasing interest. In a 2006 study, the National Coal Council called for using coal to provide at least 15% of US natural gas consumption, or 4 trillion cubic feet per year using nearly 350 million tons of coal annually. (Earlier post.)
Peabody Energy is the world’s largest private-sector coal company, with 2006 sales of 248 million tons of coal and $5.3 billion in revenues. Its coal products fuel approximately 10% percent of all US electricity generation and more than 2% of worldwide electricity.
In 2005, Peabody took a 30% stake in Econo-Power International Corporation, which owns and markets modular coal gasifiers for industrial applications.