Living off the grid

Microgrids, the concept of transforming the electricity network from a single, central network to small, localised clusters, can lead to far more reliable and environmentally friendly power supplies. So claimed Dr. Tomas Markvart of

University and Professor Ray Arnold of Siemens, in a recently published article in Ingenia, the magazine of the Royal Academy of Engineering.

Also known as 'distributed energy' or 'distributed generation', microgrids mirror the structure of early electricity distribution. In those days, hundreds of unregulated companies managed generators that each provided power to a tiny region.

Controlling supply and demand with these systems was impossible, and small generators were hopelessly inefficient, leading to a gradual transformation into a single national authority, and a few gigantic stations.

According to Markvart and Arnold's report, the "evolution of energy technologies and the consequent awareness of the environmental impacts that this can bring" has reshaped what we should be looking for. This new version of distributed energy is to have a large number of household generators connected into a low voltage local network, on the same scale as a housing estate.

Sophisticated computer systems could be used to regulate the system, exporting and importing power to larger networks only occasionally. The analogy is that of a peer-to-peer file-sharing network, where small numbers of users both contribute and benefit from the service on offer.

The advantages of such a scheme are manifold. A smaller network would find it easier to integrate electrical storage systems due to reduced size requirements. It would work better with environmentally friendly generator technologies like renewables, or micro-CHPs - combined generator/boilers which use waste heat to produce hot water. Their small power output would still be useful locally, and these generators' efficiencies are often not dependent on their size.

It would reduce the volatility of supply because failures would only affect a single isolatable network. It would cut waste during transmission, because the majority of power would only be transported a short distance, without a need for transformer stations to change voltages. Indeed, according to the report, efficiency is expected to soar to around 80%, compared to the 35-40% figure of today.

Prototype microgrids are already being designed and tested. In Germany's Nordheim-Westfalen, a training academy uses a small network containing a battery, a photovoltaic array, and a CHP system. In the US, the Consortium for Electric Reliability Technology Solutions developed a first-of-its-kind microgrid to serve Northern Power and its nearby corporate neighbourhood.

According to the report's authors, the real obstacle is regulatory and economic inertia. Ironically, the same problems that had to be addressed when centralising power must now be faced in decentralising it.

This article, written by Zhou Fang, was reproduced from

, the student newspaper of the

.