Advanced Energy Perspectives

The U.S. Environmental Protection Agency’s (EPA’s) plan to regulate carbon emissions is just the latest challenge facing the U.S. electric power system. Technological innovation is disrupting old ways of doing business and accelerating grid modernization. Earlier this year, AEE released Advanced Energy Technologies for Greenhouse Gas Reduction, a report detailing the use, application, and benefits of 40 specific advanced energy technologies and services. This post is one in a series drawn from the technology profiles within that report.

Gas turbine technology is mature and in wide use. In its most basic configuration – the simple cycle gas turbine (SCGT) – air is compressed, mixed with fuel (most frequently natural-gas), and the mixture is burned in a combustor. The resulting hot, pressurized gases are expanded through a turbine that drives the compressor and an electric generator. SCGTs have conversion efficiencies of up to about 40%. In a combined cycle gas turbine (CCGT) plant, the hot exhaust gases leaving the turbine pass through a heat recovery steam generator, which produces high-pressure steam that drives a steam turbine connected to a generator, producing more electricity with no additional fuel input. This increases overall electrical efficiency to nearly 60%, making CCGTs the most efficient conventional power plants available.

The U.S. Environmental Protection Agency’s (EPA’s) plan to regulate carbon emissions is just the latest challenge facing the U.S. electric power system. Technological innovation is disrupting old ways of doing business and accelerating grid modernization. Earlier this year, AEE released Advanced Energy Technologies for Greenhouse Gas Reduction, a report detailing the use, application, and benefits of 40 specific advanced energy technologies and services. This post is one in a series drawn from the technology profiles within that report.

A fuel cell generates electricity by electrochemical reaction, converting the chemical energy in fuel into electricity without combustion. It relies on the same principle as a battery except that the reactants are fuel and air (or pure oxygen), as opposed to the chemicals stored in a battery. Most fuel cells utilize hydrogen as fuel, with water and heat the only byproducts. With natural gas the main source of hydrogen widely available, fuel cell power plants also contain equipment for “extracting” hydrogen from natural gas through a process called steam reforming. Other fuels that have been used with fuel cells include biogas (e.g., from landfills or anaerobic digestion), and for transportation or portable applications, methanol, ethanol, and even gasoline and diesel. Fuel cells are efficient uses of fuel for electricity generation, especially compared to onsite diesel or gas generators, with conversion efficiencies approaching 60%.

The U.S. Environmental Protection Agency’s (EPA’s) plan to regulate carbon emissions is just the latest challenge facing the U.S. electric power system. Technological innovation is disrupting old ways of doing business and accelerating grid modernization. Earlier this year, AEE released Advanced Energy Technologies for Greenhouse Gas Reduction, a report detailing the use, application, and benefits of 40 specific advanced energy technologies and services. This post is one in a series drawn from the technology profiles within that report.

The U.S. Environmental Protection Agency’s (EPA’s) plan to regulate carbon emissions is just the latest challenge facing the U.S. electric power system. Technological innovation is disrupting old ways of doing business and accelerating grid modernization. Earlier this year, AEE released Advanced Energy Technologies for Greenhouse Gas Reduction, a report detailing the use, application, and benefits of 40 specific advanced energy technologies and services. This post is one in a series drawn from the technology profiles within that report.

Solid biomass has been used as fuel in power plants for many decades. The dominant technology is direct combustion in which biomass is burned in a boiler to generate high-pressure steam, which is used to turn a steam turbine-generator set. Other technologies also exist, such as gasification, in which the biomass is first converted to a synthesis gas that can be burned in boilers, reciprocating engines and gas turbines. Solid biomass resources include logging and agriculture residues, forest products residues such as sawdust, bark and spent pulping liquors, as well as dedicated energy crops, both woody and herbaceous.

The U.S. Environmental Protection Agency’s (EPA’s) plan to regulate carbon emissions is just the latest challenge facing the U.S. electric power system. Technological innovation is disrupting old ways of doing business and accelerating grid modernization. Earlier this year, AEE released Advanced Energy Technologies for Greenhouse Gas Reduction, a report detailing the use, application, and benefits of 40 specific advanced energy technologies and services. This post is one in a series drawn from the technology profiles within that report.

Water heating technology spans a range of options, from conventional technologies to renewable systems. Conventional storage water heaters typically run on natural gas or electricity and keep water hot in an insulated tank and ready for use at all times. They have a simple design and are relatively low cost, but they also have standby losses associated with storing hot water for long periods of time. High-efficiency models are available that increase the heat transfer efficiency and reduce the standby losses with more insulation. Tankless (instantaneous) water heaters eliminate standby losses by heating water on demand, creating a continuous supply, though there may be a limit on simultaneous use of hot water devices. Heat pump water heaters are electric water heaters that use heat pump technology to increase efficiency over conventional electric resistance units. Solar hot water systems harness the sun’s energy using solar thermal collectors. They typically require a larger storage tank and a backup fuel (such as electricity or natural gas) for times when the sun cannot produce enough hot water.