U. S. EPA Technology Chief: Clean Diesels Best Way To Cut Oil Imports

Detroit — Assuming that diesels evolve quickly to achieve U.S. EPA’s toughest-in-the-world vehicle emissions standards, then clean-diesels will continue to beat everything for the fastest, easiest, most economical path to cut oil dependence, according to EPA’s advanced technology division director Charles Gray.

In a presentation to a Society of Automotive Engineers (SAE) World Congress panel on oil-dependence and powertrain options, Gray predicted here that the next decade “will be the most critical for the auto industry in history.”

Rationale: soaring fuel prices, energy supply insecurity and growing consumer demand for higher-efficiency vehicles will put tremendous pressure on automakers.

“The survivors [in the auto business] will be those who act decisively now to develop high-efficiency powertrains that can enter the marketplace soon — in two to five years — and grow to high volume so they make an impact,” Gray said.

The powertrain technologies with “greatest likelihood for success” are, in order, clean-diesels, then series hydraulic-hybrids, then “high-efficiency alcohol fuel engines,” then gasoline-fueled homogenous charge compression ignition (HCCI) engines, or “free-piston engines in series hydraulic-hybrid vehicles,” although the latter two schemes will require more years of development, he cautioned. Besides consumer demands for better fuel efficiency, governments likewise are calling for actions to cut growing dependence on oil from politically unstable regions, he pointed out.

“Renewable” fuels can help somewhat, but the fact is that most of the world’s energy sources (aside from crude oil and gas) are tied up in coal, he pointed out.

“The U.S. has most of its energy in the form of coal,” with the world’s single largest reserves, whereas most of the natural gas is outside of the U.S., he said. China — the world’s fastest-growing energy market — likewise has huge coal reserves and similar worries about crude oil dependence, he added. Hence it seems logical that coal-to liquids (CTL) and gas-to-liquids (GTL) would emerge as large-volume alternatives to crude based fuels, he said. Because of the CO2 emissions problems with coal gasification, either sequestration schemes or low-CO2 process schemes must emerge, such as using nuclear, solar or wind power to provide the hydrogen and oxygen required to drive CTL processes, he said. Meantime, vehicle technologies likewise must evolve to exploit fuels more efficiently, he pointed out. That’s why EPA is cooperating in development efforts such as the hydraulic hybrid and the “clean diesel combustion” (CDC) engine.

EPA hopes to announce a third partner joining the CDC development program this spring, Gray told us in a post-presentation interview. So far, both Ford and International are working with EPA (along with engine technology developer FEV) on a project that requires an exceptionally high-boost engine as well as ultra-high-pressure fuel injection equipment (FIE) — above 2,000 bar — that’s not yet commercially available from major common-rail FIE vendors.

The CDC engine, now running in highway tests, has no problem meeting upcoming EPA nitrogen oxides (NOx) limits. But it requires refinements in exhaust-gas temperature management (including new insulation schemes), boost and FIE pressure. Ironically, CDC exhaust is actually too cold for conventional turbochargers — just the opposite problem of conventional diesel combustion. Hence the need for another expert partner to help solve boost problems, Gray told us.

Other highlights from the SAE oil dependence/powertrain futures panel here:

• National Renewable Energy Lab principal researcher Wendy Clark pointed to a recent U.S. Department of Energy/Dept. of Agriculture study showing that the U.S. potentially could replace 30% of its transportation fuel from “renewable” crops, without compromising food-grain production.
• Shell cited growing potential for both GTL and biomass to liquids (BTL) as well as cellulosic ethanol (for gasoline blending) to help offset eventual declines in crude oil supply.
• DaimlerChrysler (DCX) powertrain product engineering VP Bob Lee urged government policymakers not to push too many choices in vehicle fuels, because of the huge cost of developing engines/powertrains for specific fuels. “It’s better to have fewer fuel choices to minimize financial risk for our companies,” Lee urged.
• While DCX is rapidly expanding its “flex-fuel” vehicle offerings to enable up to 85% ethanol, it’s also moving to expand possibilities for biodiesel, especially if a uniform quality standard and quality assurance can emerge for blends of up to 20% biodiesel, he said. Hybrid vehicles, including plug-in hybrids that recharge batteries while parked, can have a positive fuel-economy impact in heavy stop-and-go duty cycles, he said. But “plug hybrids are not the appreciable answer to the tremendous challenge of energy demand,” DCX’s Lee cautioned.
• Stefan Pischinger, president of engine technology developer FEV, said that while clean-diesels are an obvious choice for reducing oil demand, high-tech gasoline evolution likewise can help. Gasoline direct-injection (GDI) technology combined with turbocharging and engine down-sizing can yield excellent fuel economy gains along with very good drivability. While hybrids can help in certain duty cycles, “the less expensive alternative to the hybrid is diesel,” he said. While the base diesel engine can cost twice as much as a base gasoline engine, “the hybrid is much higher cost” in the “full” hybrid configuration, he added.