The grid beneath

Feature story - 13 April, 2005
Even without an advanced degree, you can admire the technology behind offshore wind farms - the underwater construction, the towers, the turbines, the elegant physics of the whole thing. That these spinning blades can power homes, factories and whole cities is, well, pretty cool. This is easy to see. Obvious. What people rarely ever think about is how all that electricity gets back to shore. Enter the humble power grid.

The UK's first wind farm in the Irish Sea which will supply 50,000 homes with power.

Thoughtabout or not, power grids take years to build - especially across theocean floor. It's not like you can make do with a few kilometers ofextension cord and duct tape. There are, first off, the technicalchallenges. Salt water is not the best for electrical components, so itwill have to be kept out despite hundreds of kilos of water pressure.Then there are the distances involved, and the various environmentalconsiderations - the effects of electro-magnetic fields, noise andconstruction on marine wildlife.

Fortunately, most of these challenges already have solutions gainedfrom experience with existing wind farm instillations. No doubt a lotof hard work and cleverness will still be needed, but the technologiesinvolved are proven enough that, from an engineering perspective, thereis every reason to expect success at sea.

It's on shore that the real troubles begin - troubles that are morepolitical, institutional and bureaucratic than technical. On land thepower grid has often been built by existing old guard companies thathave their own power plants (coal, nuclear, etc.), and aren't keenabout competition from the emerging wind industry. Of course, theexisting grids are mostly optimized for the benefit of these old guardpower companies.

To put it simplistically: Starting at the power plants, big electriccable trunks branch out to smaller and smaller cables that carry asmaller and smaller amount of power. Another way to picture it is tolook at how thick the cable running into your home is. Compare this tothe much smaller wires going to individual appliances (like a lamp ormicrowave). It's sort of like water pipes, big ones branch out tolittle ones, and the one that goes to your tap is a lot smaller thenthe one going into your house from the street.

With this in mind, you can see how it doesn't work to take a big1000-megawatt cable, supplying electricity from a wind farm, and plugit into a much smaller regular street cable. But odds are that wherethe cable from a wind farm comes to shore is at the edge of the landgrid - where there are only regular street cables serving residentialneeds. Therefore, new trunk cables, and other grid infrastructure,needs to be added to accommodate the wind farm. This is not a seriousengineering problem, and is done all the time when a power plant isbuilt someplace new. Of course, the old guard power companies resistchanges to "their" power grid that will let the wind industry compete.

But if these entrenched forces can be overcome, offshore wind has hugepotential. Although it's comparatively small now, the wind industry isalready growing despite these odds (by 20 percent last year), andfuture payoffs are going to be huge. For example, with gridmodernization by 2020 offshore wind power could be supplying enoughenergy to the European Union for every single one of its 150 millionhouseholds. And, naturally, the EU doesn't have a monopoly on wind -vast potential exists around the world - but without the humble powergrid it goes nowhere.

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