1kW Recuperated Brayton-Cycle Engine
In 2013, centralized U.S. power plants had an average electricity generation efficiency of only 33%, wasting 67% of primary energy as heat and emitting 2 billion tons of CO2, about 38% of U.S. total emissions. Further, 6% of electricity is generally lost during transmission and distribution from the power plant to the customer. An alternative to centrally produced power is distributed generation, in which electricity is generated at the point of use. Residential combined heat and power (CHP) systems can burn natural gas to produce electricity for a home while also using the waste heat for space and water heating. The potential energy efficiency for CHP systems is more than 80% and significant adoption of such systems would enable dramatic reductions in primary energy use and concurrent CO2 emissions. However, usage of small CHP systems is not widespread because systems currently on the market are limited by high price, low efficiency, and short lifetime. The GENSETS program seeks to develop 1 kW (electric) CHP generators that have high fuel-to-electricity generation efficiency, long life, low cost, and low emissions.
Project Innovation + Advantages:
Brayton Energy will develop a 1 kW recuperated Brayton cycle engine to produce heat and electricity for residential use. To begin the cycle, compressed air is preheated in a recuperator before adding fuel, then the air-fuel mix is ignited in a combustion chamber. The high temperature exhaust gases then expand through the turbine, providing some of the work that drives the compressor and also produces electricity in a generator. Major project innovations include the use of a rotary screw-type compressor and expander that operate in a sub-atmospheric Brayton cycle i.e. below atmospheric pressure. In addition, Brayton will also use their innovative patented recuperator that is currently in production, and an ultra-low emission combustor.
If successful, Brayton Energy’s project will facilitate development and commercialization of economical, efficient, and durable CHP systems for residential use. These advancements support progress toward ARPA-E’s overall goals as follows:
Innovations developed in this project could help households and businesses become more energy self-reliant and less susceptible to energy-related outages through distributed, local generation of power and heat.
Widespread adoption of high-efficiency residential CHP systems could decrease overall primary energy consumption and therefore reduce CO2 emissions associated with electricity generation by up to 10%.
Cost-effective natural gas-fueled residential CHP systems could offer consumers lower electricity and heating bills.