Penn State press release:
Adding a little coal and processing the papermaking industry's black liquor waste into synthesis gas is a better choice than burning it for heat, improves the carbon footprint of coal-to-liquid processes, and can produce a fuel versatile enough to run a cooking stove or a truck, according to a team of Penn state engineers.
"Black liquor is routinely burned in a recovery boiler," said Andre Boehman, professor of fuel science. "But it has more energy value as a synthesis gas, which is then used to create other fuels."
Black liquor is a combination of lignin from the wood, the chemicals used in papermaking and water. Normally, after burning, mills extract the inorganic chemicals and recycle them. Synthesis gas or syngas can be made from a variety of organic wastes and is a combination of hydrogen and carbon monoxide. The final product looked at by the researchers is DME or dimethyl ether. . . .
DME is building new markets in both heat producing fuel applications and transportation. In Japan and China, some demonstration diesel trucks and buses already run on DME. Volvo has a third-generation experimental truck that runs on DME, and other companies are also testing vehicles.
(Penn State) students looked at the efficiency of using black liquor as the feedstock for manufacturing synthesis gas and then DME, and realized that they needed the economy of scale for the process to be really efficient and economical. The capacity of paper mills for fuel production could be expanded by co-processing coal with the black liquor.