Courtesy Marathon Engine Systems

Though currently a footnote among conventional heating systems, the residential (or “micro”)-scaled version of industrial cogeneration is poised to find a foothold in housing.

Using natural gas or propane to fuel energy for space and water heating, micro CHP units measuring about the size of a large A/C compressor create on-site electricity as a free by-product of their combustion engines; that electricity offsets power from the grid, while any surplus spins the meter backward and earns energy credits.

The residential-sized version of the technology has been available in the United States for just a few years, much longer in Europe, with companies including Freewatt, Marathon Engine Systems, and Yanmar America Corp. pushing for larger market share and legitimacy, both goals aided after Marathon’s EcoPower unit earned the Energy Star Emerging Technology Award for 2011.

But in the more advanced European market, where Marathon has installed more that 3,000 micro CHP units in homes and (mostly) light commercial buildings since 2001, the next generation of cogeneration is emerging to produce electricity at peak-rate times.

In her recent article Making Renewable Energy Work Better: “Swarm Power” Cogeneration,’s Jennifer Atlee provides insight into the latest version of micro CHPs and the prospect of free (or at least less expensive) grid-supplied power and energy independence inching closer.