Coal may lead way to hydrogen economy
Coal is the leading contender to provide a
hydrogen source in the near term.
“While some day we may be able to produce hydrogen by breaking up water molecules in association with the high-temperature heat from nuclear power reactors, or through renewable energy technologies, right now the most cost-effective way to produce hydrogen is with coal,” says Chris Shaddix, principal investigator for clean coal combustion at Sandia’s Combustion Research Facility.
Two different approaches to burning coal are now under study:
* The first, called oxy-combustion, combines coal with pure oxygen.
* The second, called gasification, burns coal only partially to create a fuel-gas.
The first approach is driven by concern over emissions of CO2 and other pollutants. The burning of coal in oxygen is a near-term solution that with current knowledge can produce exhaust streams that are close to pure CO2, says Shaddix. Harmful pollutants like nitrogen oxides, sulfur compounds, and mercury are virtually eliminated.
The oxy-combustion approach is favored by companies in Japan, Canada, Germany, and elsewhere, where pilot plants are under construction.
U.S. companies tend to favor gasification technologies, which offer higher efficiency and low pollution formation. One of these technologies, called steam reformation, combines the coal with steam in a hot environment to produce a “syngas,” composed mostly of carbon monoxide (CO) and hydrogen.
Once the syngas is produced it can be burned directly in a turbine to produce power. Or the syngas can be further reacted with more steam to shift the remaining CO to CO2 and produce more hydrogen.
The competition between Sandia and Los Alamos is a spectator sport here in New Mexico. At least when they take the time to work at civilian rather than military tasks.
Posted: Thu - April 6, 2006 at 08:49 AM