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Saturday, December 13, 2003

Intelligent Energy: Combined Heat and Power + Stirling engines
Last week Earth-Info.Net attended a presentation given by a company called Microgen who produce domestic combined heat and power (CHP or co-generation) units.

Their wall mounted units use natural gas to produce hot water, heating + electricity within individual households.

Micro CHP units are very efficient, as they allow hot water to be produced on demand, heating to be generated without energy disappearing up power station chimnies, and electricity to be produced without the losses associated with dissipation over long-distance transmission lines (see the illustration on page 4 of their brochure).

These units combine a modern boiler (that produces low carbon dioxide emissions) with a sterling engine, that can be used to generate electricty...

A sterling engine is a highly efficient (up to 50% of the theoretical maximum), four phase external combustion engine invented, in 1816, by a Scottish clergyman, Rev. Robert Sterling, who was shocked at the danger exploding steam engines then posed to his parishioners.

There are now two main types of sterling engine, both of which rely on a external heat source causing gas within a cylinder to expand, while cooler air contracts in another part of the engine, resulting a flow of air that can, when carefully timed, be used to drive pistons.

Normally, this is done via either two strokes (one hot + one cold) within a single cylinder or single strokes within two cylinders (this will probably only make sense if you look at the animations these two links offer!).

Combined heat and power was first brought to Earth-Info.Net, as an emerging trend, by one of the alternate scenario reports produced by Shell, called Energy Needs, Choices + Possibilities.

This report and the others in the series are of general interest because they give well argued hints as to the social, economic and resources issues that what will be driving decision making within big business, government + society over the next 20-50 years.

Many of the scenarios are quite alarming, especially if you are poor, have low skills or need to import energy... they also suggest that the companies and countries which are slow to learn about, prepare for, and adapt to, new types and sources of global change, including energy supply, will be left in increasingly vulnerable positions.