Last February, I issued a significant zing to ASHRAE and TIAX concerning their biased coverage of fuel cells for distributed generation; see “Fuel Cell Optimists Get Called Out”. This series of articles appeared in the ASHRAE Journal between November 2006 and March 2007. My general impression was that the authors at TIAX, LLC were portraying fuel cells through far too rosy a lens while ignoring some significant fundamental technology issues that remain to be solved.
More recently, I ranted on the complete absurdity of the term “microturbine” to describe aero-engine-derived terrestrial gas turbine power plants because their working components are on the order of centimeters, not microns; see “There’s Nothing Micro about Microturbines”. In this article, I mentioned that microturbines have more serious problems than improper nomenclature, but I failed to go into detail.
Someone at TIAX must be reading my blog.
The TIAX folks have somewhat redeemed themselves through their short April 2007 ASHRAE Journal article, this time concerning microturbines. To my surprise, the previous rosy, utopian, Kumbaya take on advanced energy generation has been dropped for the microturbine article, and the drawbacks of this technology are laid bare for all to see. Why couldn’t we have had this kind of honesty in the fuel cell articles?
The problem with microturbines is their sub-par efficiency. According to the DOE Buildings Energy Databook, grid-supplied electricity is about 31.5% efficient. By contrast, commercially-available microturbines top out at about 28.9% efficiency, according to “Gas-Fired Distributed Energy Resource Technology Characteristics” published by the GTI and NREL. This disparity is nicely outlined in the April 2007 TIAX article.
Since microturbines mostly burn non-renewable fossil fuel (usually utility-supplied natural gas), their below-grid efficiency means that its better for the environment and the pocket book to pull electrons from the grid then generate them on-site with a microturbine. Only in a few niche markets do microturbines make economic sense.
Thanks TIAX for your honest coverage of microturbines!