Biodiesel has a number of benefits. As an alternative to diesel, it can help reduce U.S. dependence on foreign oil. Biodiesel also provides significant greenhouse gas (GHG) emission reductions. In addition, biodiesel offers several emissions bene- fits for the existing vehicle fleet. It reduces emissions of carbon monoxide, particulate matter (PM) and sulfates, as well as hydrocarbon and air toxics emissions.
A 2002 EPA summary analysis of existing data suggests vehicles using biodiesel may emit slightly more nitrogen oxide (NOx) (about 2 percent for B20 and 10 percent for B100). Subsequent studies have yielded mixed results, with some showing small increases and others showing small decreases. The EPA plans a further investigation to fully assess this issue, including the emissions impact of using biodiesel in vehicles equipped with PM traps and NOx aftertreatment designed to meet strict new emission standards.
Headquartered at the EPA's National Vehicle and Fuel Emissions Laboratory in Ann Arbor, Mich., the EPA's engine research focuses on developing engines that are simultaneously clean, efficient and cost-effective.
Clean Diesel Combustion technology is one example of these innovative engine concepts. The EPA's testing suggests the potential for a diesel engine design. It uses a new air, fuel and combustion management with a conventional particulate matter aftertreatment to achieve lower NOx levels. The EPA is developing this technology as a potential alternative to other diesel emissions control approaches. Clean Diesel Combustion technology shows great potential for real world benefits. Thus, the EPA has partnered with several automotive and engine manufacturers to evaluate the production feasibility of this technology.
The EPA is a research leader in the application of hydraulics in vehicles. Hydraulic hybrid technology uses a hydraulic energy storage and propulsion system in the vehicle - and holds great promise for the future of urban driving.
A hydraulic system captures and stores a large fraction of the energy normally wasted in vehicle braking and uses this energy to help propel the vehicle during the next vehicle acceleration. The hydraulic system also enables the engine to operate more efficiently when it is needed.
Hydraulic hybrids draw from two sources of power to operate the vehicle - the diesel or gasoline engine and the hydraulic components. In other words, a typical diesel-powered or gasoline- powered vehicle can be fitted with hydraulic components as a secondary energy storage system.
BENEFITS OF HYDRAULIC TECHNOLOGY
Hydraulic drivetrains are particularly attractive for vehicle applications that entail a significant amount of stop-and-go driving, such as urban delivery trucks or buses. A major benefit of a hydraulic hybrid vehicle is the ability to capture and use a large percentage of the energy normally lost in vehicle braking. Hydraulic hybrids can quickly and efficiently store and release great amounts of energy. This is a critical factor in maximizing braking energy recovered and increasing the fuel economy benefit. While the primary benefit of hydraulics is higher fuel economy, hydraulics also increases vehicle acceleration performance. Hydraulic hybrid technology cost-effectively allows the engine speed or torque to be independent of vehicle speed, resulting in cleaner and more efficient engine operation.
HOW IT WORKS
The newest generation of hydraulic vehicles replaces the conventional drivetrain with a hydraulic drivetrain and eliminates the need for a transmission and transfer case. The primary components are the hydraulic accumulator and one or more hydraulic pump/motor units.
These components work together in a very simple way: