Technical and economic feasibility of a prototype 4 kW cogeneration package

We report on the technical and economic evaluation for a utility company of a new prototype, gas-fueled, 4-kW cogenerator. This unit is targeted for use by a small business or homeowner to heat water and generate electricity. We describe the experimental setup used to test this cogenerator and measure power output, electrical voltage and frequency, thermal output, natural gas consumption, noise levels, reliability, and economics. The prototype had an overall efficiency of 45% vs a target of 72% for economic viability. The electrical output did not meet the electric utility requirements of 60 ± 0.5 Hz and 240 ± 5% V; instead, the output varied from 55 to 60 Hz and 220 to 300 V. For most cases, a small business or homeowner would receive a low rate of return and a payback period that exceeds the life of the cogenerator unless the efficiency can be increased by about 25%.