Daily Archives March 4, 2016


1.3 Overview

Economists have overwhelmingly favored fuel taxes over fuel economy standards as a means to reduce fuel consumption because taxes give maximum flexibility to both vehicle manufacturers and purcha­sers and because they influence fuel consumption through both fuel demand and vehicle supply by making travel more expensive (thereby reducing vehicle miles traveled) and by creating an economic incentive for manufacturers to build efficient vehicles and for consumers to purchase them. However, it is important to note that the presumed superior effectiveness of fuel taxes over CAFE standards depends on the assumption that markets for fuel economy and travel are very efficient...

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The Japanese Top-Runner Selection Process

The new Japanese weight class standards for LDV fuel economy are based on identifying top runners— vehicles with exemplary fuel economy—in each weight class and requiring future vehicles in that class to attain similarly high fuel economy. Accord­ing to Japanese industry sources, the top-runner selection process is more nuanced than simply selecting the highest fuel economy vehicle in each class and establishing that as the standard. Instead, the regulators—the Ministry of International Trade and Industry (MITI) and the Ministry of Transpor­tation (MOT)—with the consultation of the Japa­nese Auto Manufacturers Association (JAMA), select top-runner targets based on their judgment of the relevance of class-leading vehicles and their technology to the class as a whole...

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Japanese Weight Class Standards

The Japanese government has established a set of fuel economy standards for gasoline – and diesel-

powered light-duty passenger and commercial vehi­cles, with fuel economy targets based on vehicle weight classes. Table I shows the vehicle targets for gasoline – and diesel-powered passenger vehicles, as measured on the Japanese 10.15 driving cycle. The targets for gasoline-powered vehicles are to be met by 2010, and 2005 is the target year for diesel-powered vehicles. Figure 1 illustrates the percentage improvements required for each weight class of gasoline-powered vehicles as well as the market share for each class at the time the regula­tions wave created. The original regulations de­manded that the targets be met by each automaker
for each weight class; that is, automakers could not ...

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Superconducting Magnetic Energy Storage Superconducting magnetic energy storage (SMES) systems store energy in the field of a large magnetic coil with DC flowing. It can be converted back to AC electric current as needed. Low-temperature SMES cooled by liquid helium is commercially available. High-temperature SMES cooled by liquid nitrogen is still in the development stage and may become a viable commercial energy storage source in the future. SMES systems are large and generally used for short durations, such as utility switching events

1.1.2 Supercapacitor

Supercapacitors (also known as ultracapacitors) are DC energy sources and must be interfaced to the electric grid with a static power conditioner. Small supercapacitors are commercially available to extend battery life in electronic equipment, but large super­capacitors are still in development.

1.1.3 Compressed Air Energy Storage Compressed air energy storage uses pressurized air as the energy storage medium. An electric motor-driven compressor is used to pressurize the storage reservoir using off-peak energy and air is released from the reservoir through a turbine during peak hours to produce energy. Ideal locations for large compressed air energy storage reservoirs are aquifers, conven­tional mines in hard rock, and hydraulically mined salt caverns...

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Battery Storage

The standard battery used in energy storage applica­tions is the lead-acid battery. A lead-acid battery reaction is reversible, allowing the battery to be reused. There are also some advanced sodium-sulfur, zinc-bromine, and lithium-air batteries that are
nearing commercial readiness. Batteries suffer from limited storage capacity and environmental concerns over their manufacture and disposal processes.

1.1.1 Flywheel

A flywheel is an electromechanical device that couples a motor generator with a rotating mass to store energy for short durations. Conventional flywheels are ‘‘charged’’ and ‘‘discharged’’ via an integral motor/generator. The motor/generator draws power provided by the grid to spin the rotor of the flywheel...

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Additional important characteristics of the stan­dards are as follows

• Low-volume manufacturers. The standards can be waived for low-volume manufacturers, that is, those producing fewer than 10,000 passenger cars annually worldwide.

• Vehicle weight limits. The standards apply only to vehicles whose gross vehicle weight rating (GVWR) is 8500 pounds or less. A number of large sport utility vehicles have GVWRs above this level and are not subject to the standards.

• Setting and amending standards. The U. S. Congress set the original schedule for passenger car standards and authorized the National Highway Traffic Safety Administration (NHTSA), in the Department of Transportation, to set the light truck standards. Manufacturers were required by Congress to comply with the 27...

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Wind Turbines

Wind-based power generation may or may not be a DE technology, depending on whether it is located near the demand source or at a remote wind farm. Generally, wind turbines are located in areas with good winds and have annual capacity factors ranging from 20 to over 40%. The typical life span of a wind turbine is 20 years. Maintenance is required at 6- month intervals.

A wind turbine with fan blades is placed at the top of a tall tower. The tower is tall in order to harness the wind at a greater velocity and to be free of turbulence caused by interference from obstacles such as trees, hills, and buildings. As the turbine rotates in the wind, a generator produces electrical power. A single wind turbine can range in size from a few kilowatts for residential applications to greater than 5 MW.

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PV cells, or solar cells, convert sunlight directly into electricity. PV cells are assembled into flat plate systems that can be mounted on rooftops or other sunny areas. They generate electricity with no moving parts, operate quietly with no emissions, and require little maintenance. An individual photo­voltaic cell will typically produce between 1 and 2 W. To increase the power output, several cells are interconnected to form a module. Photovoltaic systems are available in the form of small rooftop residential systems (less than 10kWe), medium-sized systems in the range of 10 to 100 kWe, and larger systems greater than 100 kWe connected to utility distribution feeders.

Two semiconductor layers in the solar cell create the electron current...

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