George Monbiot : Build a Europe-wide "Super Grid"

Build a Europe-wide "Super Grid"

Many environmentalists love the idea of micro electricity generation: producing their own power at home, from wind turbines or solar panels on the roof. It seems instinctively right - small is beautiful, isn't it? Well I hate it. Let me try to explain why.

The first reason is that it is staggeringly inefficient. For good reasons, people tend not to live in the places where ambient energy is most abundant: deserts, mountaintops and oceans. In high latitudes (the UK, for example), sunlight is weak, especially when we need the most electricity (demand peaks between 5 and 7pm on winter evenings). Windspeeds in most cities are low. This means that microgeneration is an extremely expensive way of generating electricity. A pound spend on an inefficient solution is a pound not spend on an efficient one.

Worse still, a local electricity network of the kind recommended by Greenpeace (among others) confronts an intractable problem. If the local energy sources fail - in other words if night falls and the wind stops blowing - there is no fallback supply of renewable energy. This means that you must rely on either overcapacity and a great deal of battery power (which is a wasteful use of rare resources) or on fossil fuels to fill in the gaps. Microgeneration looks at the problem through the wrong end of the telescope.

We need to tap renewable energy where it is most abundant and transport it to the places (where we live) in which it is least abundant. The key task is to make renewable energy more reliable, and this means tapping the greatest possible diversity of sources, as far apart from each other as geography allows. Picture a system which is the precise opposite of Greenpeace's local micro-grids. Imagine a European supergrid tying together the richest sources of renewable energy: wind in the North Sea and the Atlantic, hydropower in the Alps and Scandanavia, geothermal power in Iceland, solar thermal power in the Sahara. If the wind fails in the North Sea, there's a high chance it's still blowing in the Atlantic. If it fails everywhere, you ask the Austrians and the Norwegians to open their sluices. The Sahara is the best source of all: not only is the sunlight there reliable and strong, but the desert runs from east to west, which means that soon after the sun goes down at one end it comes up at the other. Solar thermal plants strung out across the Sahara could supply Europe with something like 15 hours of solid renewable electricity per day, covering all the periods of peak demand.

Studies by the German government, the Centre for Alternative Technology and Mark Barrett at University College London suggest that we could produce all or nearly all of our electricity by this means, without any greater risk of power failure than we run at the moment.

Does this sound like science fiction to you? In the past people have objected that the distances are just too great: you would lose so much electricity across those thousands of miles of cables that it wouldn't be worth generating. But here's where the breakthrough technology comes in. The key environmental technology is not a generator or even an energy efficiency device. It's a transmission technology called the high voltage direct current cable.

At present we transmit almost all our electricity by means of alternating current. That's fine over short distances, but beyond a few hundred kilometres the "line losses" - the power dropped along the way - become overwhelming. Direct current cables, by contrast, lose very little energy in transmission. There's already an HVDC cable in the Democratic Republic of Congo 1800 kilometres long. The maximum economic length is some 4-5000km - quite long enough to build a European, possibly even a global, supergrid. The DC cables bring electricity in from afar, which is then tapped into our domestic AC networks. This, to me, is the key to decarbonising our electricity supplies, perhaps eventually our entire energy system.