BURNING coal polluted our skies well into this century. Then the burning of other carbon-based fuels continued the pollution. As a result, we face concerns today about possible climate change from emitting carbon into the atmosphere. In the Energy Directorate, where we join together the expertise of multiple disciplines from throughout Lawrence Livermore, we are addressing these concerns with innovative research in carbon management technologies.|
There are three basic strategies for reducing carbon emissions into the atmosphere. First, we can use fuels that contain less carbon (for example, natural gas), find better ways to manufacture low-carbon fuels (methanol, liquefied natural gas, and hydrogen), and produce electricity with renewable resources and nuclear fission instead of coal. Second, we can improve energy efficiency in all use sectors-whether utility, transportation, industrial, residential, or commercial. And third, we can develop low-cost carbon separation and sequestration technologies.
The article entitled The Internal Combustion Engine at Work--Modeling Considers All Factors addresses part of the second strategy: improved efficiency for the transportation sector. By applying our fundamental understanding of combustion chemistry, nonthermal plasmas, and catalytic processes to the venerable piston engine, we are working to improve engine efficiency and thereby allow the public more engine choices.
Over the past 25 years, Livermore has developed chemical kinetic models for studying ever-more complex systems of hydrocarbon fuels. Livermore scientists have gained insight into the processes that produce pollutants-the hydrocarbons, oxides of nitrogen, carbon monoxide, and particulates-that now are regulated. Using the models, designers have modified engines to reduce emissions to the point that with after-treatment technologies (catalytic converters), the engines can meet ever-tightening regulatory limits.
Now the challenge is to reduce the amount of carbon dioxide that automobiles and trucks emit per mile. Not yet regulated, these emissions are at the heart of carbon management for vehicles. The Partnership for a New Generation of Vehicles-a consortium of the three U.S. automakers, national laboratories, and industry for studying fuel-engine relationships-has concluded that the most viable technology for reducing the carbon dioxide emissions of lightweight vehicles is the diesel engine, probably in hybrid drivetrain configurations. Using lightweight materials, improved aerodynamics, and lower rolling resistance, we can build diesel cars that provide 60- to 70-mile-per-gallon efficiency with only a small increase to their cost. But the current diesel engine does not meet the regulatory standards that will be in place in the next decade, so we are researching after-treatment technologies for diesels.
We are also examining modified, or reformulated, diesel fuels. We are keenly aware of the recent history of MTBE contamination of water supplies and understand that the full environmental effects of fuel modifications must be carefully examined.
Another major project is a totally new engine combustion system known as Homogeneous Charge Compression Ignition. It does not produce significant emissions of oxides of nitrogen, thus making after-treatment of the hydrocarbons simple. If control mechanisms can be found for these engines, they may be as efficient as diesels and cost less.
Of course, none of this research will have any effect if it does not move into the marketplace. We are working closely with industry to understand the real-world constraints of all of these technologies. We want our work to result in viable options while also reducing industry's technical risk.