Coal: An energy bridge to the future

Because domestic coal supplies are plentiful, PNNL researchers are looking at whether it can be cleanly and efficiently converted to transportation fuels to replace some of the 12 million barrels of oil the United State now imports per day.

For years, coal drove the transportation business in this country, and it may be poised for a comeback. A hundred years ago, steam engines burned tons of coal as they pulled trains across the country. Now researchers are looking at converting that coal to liquid fuel to fill our gas tanks and move cars and trucks.

"With the price of gas painfully high and with the negative foreign trade balance and national security issues associated with importing oil from other countries, coal is getting more than a second look," said George Muntean, who manages PNNL's Energy Conversion Initiative.

The technology already exists to transform coal into a liquid fuel. In fact, Pacific Northwest National Laboratory scientists and engineers have researched forms of coal and hydrocarbon gasification on and off for more than 30 years. But oil has never sustained a high enough price to kickstart a coal-to-liquid fuel industry.

That might be changing now. Plus, experts agree worldwide petroleum resources won't last forever, and hydrocarbon resources like coal may be the only resources available, at a large enough scale, to off-set oil consumption, in the near term.

"If coal is used cleanly and efficiently, it can serve as an energy bridge to the future in which renewable energy and nuclear and hydrogen-based energy sources will make up our energy systems," said Mike Davis, associate laboratory director for the Energy Science and Technology Directorate.

The United States has the largest coal reserves anywhere--about one fourth of the world's supply. But, historically, its impact on the environment has been problematic. While the process of converting coal to a liquid is inherently cleaner than burning coal to produce electricity, there are still challenges with water usage and air emissions-- especially carbon dioxide. CO2 is implicated in global warming. Solving the CO2 problem is one of PNNL's biggest strengths when it comes to utilizing coal. "We are at the forefront of research into carbon capture and sequestration," said Muntean.

Gasifiying coal releases CO2 but also produces a very highquality synthesis gas. The process to convert this so-called syngas to liquid fuel is called Fischer-Tropsch, after two German scientists who developed the technology in the early 20th century. It was employed, in conjunction with coal gasification, during World War II when Germany had trouble importing sufficient petroleum.

The liquid fuel produced from coal can be blended with traditionally refined fuels, used by existing diesel engines and transported and delivered in the same manner as the diesel we're all familiar with, so no change in infrastructure is needed. PNNL recently launched an Energy Conversion Initiative--an investment in identifying the science and technology challenges and defining the conditions for commercial success needed for economically and environmentally sound use of domestic hydrocarbons, such as coal.

In addition to the Laboratory's expertise in carbon capture and sequestration, researchers are building on capabilities in FT synthesis, catalysis and nanotechnology, separations, materials and sensor development to make the conversion process more efficient--better, faster, cheaper--and to reduce capital costs of building coal-toliquid production plants.

PNNL is engaged with state governments that are interested in using their coal resources for transportation fuels. PNNL hopes to create government-industry partnerships that will develop process capabilities that can be demonstrated in pilot or full-scale commercial plants within five years. "If we can tap this domestic resource in a way that doesn't harm the environment, we can really make a dent in the 12 million barrels of oil we import each day," Davis said. "I believe it can be done."