Micro Combined Heat and Power

About a year ago, I read an article about small-scale or micro combined heat and power (CHP) units. In the traditional situation, you burn fuel locally for water and space heating, and you get electricity from the grid. That electricity comes from a power plant that is producing an enormous amount of excess heat. Wouldn't it be good to be able to capture that heat for use in water and space heating? Alternatively, how about putting the power plant locally, so you can use the excess heat? That is what the micro-CHP is all about: local power generation combined with heat capture.

Immediately, I contacted the company that was offering CHP generators for commercial and residential applications. I signed a contract for a unit last February, and I've been waiting ever since for the installation. Part of the problem was that the engine was not UL rated, and apparently they spent some time getting the unit through all the tests. We are currently waiting for Connecticut Light and Power to grant approval to connect this to the power grid. There shouldn't be any problem, for the solar panels have already been approved for grid-tie. In pushing the envelope in this area, I've noticed you have to spend a lot of time waiting for things to get done.

In my mind, this co-generation technology will be revolutionizing power generation. We are about to the break the utility monopoly paradigm, and it will be economical, because, as shown in the last post, an enormous amount of energy is wasted in the traditional power generation scheme. With local production, you can gain back the lost heat for local uses, and the savings will offset the so-called economies of scale that larger power plants offer. It isn't clear if this is available everywhere, but in the State of Connecticut, they are committed to introducing cleaner power technologies, and CHP certainly qualifies.

Distributed or local generation offers other advantages as well. First among them is that the need for power lines is reduced, and so are the losses associated with them. Distributed generation also allows for (but does not guarantee) a more stable grid structure. This is a big deal locally, where the power company is running new underground high voltage lines in an effort to increase the grid robustness (and more than likely, to increase the amount of power they can sell into Long Island). If the distributed generation takes off, we will not be needing to do much more of that--ever.

Information on combined heat and power units is given at the Marathon Engine website. Here is a diagram of a typical layout. (Click on the figure for a larger image.)



I will be posting more information on our actual configuration at a later date. This technology presently is not economical for the average residence (although with some changes, I think it could be), but because we have geothermal heat pumps, we use about twice as much power (with a corresponding reducton in fuel use for heating) as the average residence, and this helps make our installation economical. I'm hoping on synergies between the the CHP and the geothermal that will then make the geothermal even more economical, but for now, I'm just waiting for this to get installed to actually measure how much we will be saving with the CHP.