Blending ethanol into petroleum diesel at levels of between about 7 and 15% has been demonstrated to yield significant reductions in particulate emissions, even with new engines equipped with state-of-the-art emissions control technologies. Keeping ethanol and diesel in a single, clear solution can be accomplished using a variety of materials (some proprietary), including biodiesel. More work is needed to definitively establish effects on horsepower and fuel economy, and on emissions of hydrocarbons, CO, and NOx. The National Renewable Energy Laboratory is preparing an ethanol–diesel blends technical assessment and will present an October 2001 workshop on critical technical barriers and how to address them, with the objective of establishing an ethanol–diesel blend government–industry consortium for commercial advancement.

Using a "clean-sheet-of-paper" design approach, EPA researchers have begun developing a direct-injection, four-cylinder powerplant that runs on alcohol. Currently fueled with methanol, the engine is expected to run on ethanol, and was designed for integration with an electric motor in a hybrid powertrain. According to EPA, the engine should cut NOx emissions by 50 to 80% while operating 5% more efficiently than a diesel engine. The EPA prototype will have to compete with direct-injection diesels, which the automakers believe will be able to meet tougher air quality standards with upcoming pollution control technologies.

Medis Technologies recently announced that is has successfully demonstrated that its DLM fuel cell can utilize a broad range of alcohols (including ethanol) or mixture of alcohols as fuel without affecting the performance or longevity of the fuel cell. The company said its DLM fuel cell is able to utilize alcohol fuels such as ethanol because of a special architecture in the fuel cell that prevents fuel migration to the cathode. In addition, the fuel cell uses a liquid electrolyte instead of a proton exchange membrane.

Commercial fuel cell configurations include proton exchange membrane (polymer electrolyte), direct methanol, alkaline, phosphoric acid, molten carbonate, solid oxide, and others. Each configuration has its own unique set of operating conditions and requirements, and none is ideally suited for all energy applications. The EERC is preparing an assessment of which configurations and applications offer the best technical, logistical, and economic match for ethanol, both in the near and long term. A near-term option being explored is PEM fuel cells integrated with a reformer capable of extracting hydrogen from ethanol, methanol, or any mixture of the two. Under this scenario, ethanol could be denatured using methanol instead of gasoline, which would eliminate the higher energy requirement associated with reforming gasoline. Another option involves using ethanol to fuel smaller (300-kW to 1-MW) hybrid solid oxide fuel cell–gas turbine powerplants for stationary electricity generation.

NREL is initiating a long-term program to look at critical technical issues associated with making renewable fuels work in fuel cells. Issues related to ethanol will likely include fundamental research on impurity levels and their effects on fuel cell performance, and hydrogen concentration requirements. A workshop on research needs for transportation fuel cell fuels is scheduled for October 2001.

In response to a recent request from the U.S. Federal Aviation Administration (FAA), the AGE85 team is designing a joint-venture project with major aviation industry partners to demonstrate the safety and performance of ethanol-based aviation fuel for piston engine aircraft, and begin the process for achieving ASTM certification of an ethanol-based aviation fuel. The general aviation industry is in recovery mode and currently represents a fuel market of about 400 million gallons per year, which is down from its historic high of about 700 million gallons per year during the late 1970s and early ‘80s, but up from its historic low of about 300 million during the early ‘90s.

Producing ethanol from grains at low temperatures may be more feasible due to improved enzymes developed in the laboratory, according to ARS scientists. Currently, starch is cooked at about 223°F to enable enzymes to convert it into simple sugars. ARS scientists have developed variants of a natural starch-degrading enzyme that breaks down starch 50 times faster than the original enzyme in the laboratory, at about 99°F. Enzymes with greater activity at low temperatures could facilitate development of more energy-efficient ethanol production methods and improve production from wheat, barley, and other grains.

BRI has developed biomass gasification–fermentation technology that can produce ethanol from cellulosic wastes at high yields and rates. The process uses gasification to produce a "syngas" of carbon monoxide, carbon dioxide, and hydrogen, which is then converted to ethanol by anaerobic bacteria such as Clostridium ljungdahlii. Conversion rates are high because the process is limited by the transfer of gas into the liquid phase, instead of the rate of substrate uptake by the bacteria. Feasibility of the technology has been demonstrated, and a pilot plant project is underway. Unlike acid hydrolysis-based processes, which do not result in conversion of lignin to ethanol, gasification–fermentation processes can convert all feedstock to ethanol except ash and metal. Other groups are working on gasification followed by Fisher–Tropsch condensation to yield ethanol. Gasification approaches have always worked well technically, and recent developments have improved their economics.

"Permeation" is the migration of molecules through the various elastomers in a vehicle’s fuel system. According to the Haskew report, the substitution of ethanol for MTBE in California gasoline will increase hydrocarbon evaporative emissions of the existing fleet, mainly because ethanol increases permeation, even from newer vehicles, and also from non-road vehicles, lawn and garden equipment, and plastic fuel storage containers. The report recommends a "quick test program" to estimate permeation rates from ethanol-blended and nonethanol fuels using six different vehicles. The recommended vehicle model years: one 1984, two 1985s, and a ‘92, ‘93, and ‘94.