LATER this year, when Queen Elizabeth turns 80, she will see a dramatic drop
in her electricity bills. This is not a special deal for the
The £1 million scheme, which will supply up to 200 kilowatts of electricity, is being developed by the electricity generating company Npower. The generators will be driven by four turbines now being built into Romney weir, about 800 metres from the castle. The generators will make a substantial dent in the royal electricity bill, supplying about a third of the castle's needs. And the cost of the upkeep will be minimal. "Once they're in you can pretty much leave them alone," says Patrick Spink of Npower Renewables, the company installing the turbines. "They are likely to be there for 100 years."
Not everyone has a large river at the bottom of their garden. But almost all
of us can trim our utility bills by generating our own energy. Photovoltaic
tiles or a small wind turbine on the roofs of houses or apartment blocks are no
longer a rarity. If these and similar small-scale generators were installed in
large numbers they could have a significant impact on energy policy, helping to
slash carbon emissions and taking the strain off overloaded distribution grids.
A growing enthusiasm for renewable energy has also stimulated development of
new small-scale energy generators that are reliable, simpler to install and,
most importantly, capable of exporting the power they create onto the grid.
"The potential is pretty significant," says Dave Sowden of the
Micropower Council, the
Faced with record oil prices and a desire to cut carbon emissions, most governments are looking at alternatives to fossil fuels. But can converting homes into power stations really turn conventional energy policy on its head? How much power can microgeneration contribute, and what technical issues must be solved before we can all begin to harvest and sell our own energy?
A single 1.5-kilowatt wind turbine seems insignificant compared to a
1000-megawatt nuclear power station, which some tout as the only hope of
curbing greenhouse emissions. But according to a recent
Microgeneration can bring several advantages. Energy from wind, water or the
sun does not depend on gas or oil from countries whose governments can turn off
the tap without warning or hike up the price. On top of that, the EST estimates
that by 2050, microgeneration could cut the
So what qualifies as a microgenerator? In the
Even the Archimedes screw has been transformed into a microgenerator, thanks
to Ritz-Atro, a company based in
A study last year by Amory Lovins of the Rocky Mountain Institute in
Part of the attraction of small-scale generation is that it is well suited to renewable sources of energy such as wind, water and solar. These can be used in conjunction with micro-combined heat and power (micro-CHP) units, in which some of the heat output of a gas boiler is used to make electricity. "One of the beauties of microgeneration is that the technologies are complementary," says Walt Patterson, an energy specialist with the London-based think tank Chatham House. "If the sun isn't shining, it's often windy." Just as usefully, the electrical output of a micro-CHP unit follows a consumer's demand for heat. So while photovoltaic cells produce electricity during daylight hours, micro-CHP can kick in when people come home in the evening and switch on their heating.
Small-scale power generation has other advantages, too. Producing power
locally avoids distribution losses, which account for about 10 per cent of the
electricity fed into the grid. This also helps ensure security of supply, says
Lovins, by avoiding the power cuts that arise when the grid fails - the main
reason for power failures in the
According to Mike Bergey, president of Bergey Windpower of
One problem with small-scale generators is that their power output
fluctuates. If you have a wind turbine on your roof, you'll need electricity
from some other source when the wind dies. And if you're away from home when
it's windy, you'll generate more electricity than you can use. The obvious
answer is to buy in extra power from the grid when needed, and sell power back
to the grid at times when you are generating a surplus. But the electricity
grid was built to distribute power, not receive it. As a result there are a
number of obstacles, both technical and commercial, to doing this. Power companies
in many countries prefer not to let smaller generators connect to their grids
as they fear technical problems could arise. There is often no system for
paying microgenerators either. In the
Power companies are frequently obstructive, says Lovins, and may demand
exhaustive engineering studies before allowing a connection. "I think the
basic problem is that most
There also needs to be a fair system to pay people for the electricity they generate. But what price is fair? There is general agreement that households should be paid less for the power they sell than they are charged for the power they buy, to cover the cost of installing and maintaining the distribution network. It's just how much the difference should be that is in dispute.
Such commercial problems are mirrored by technical ones. Electricity meters
were designed to monitor how much power a household consumes, not how much it
produces. A survey by the
The simplest solution would be to wire in a separate meter to measure electricity exports, so that they can be paid at the appropriate rate. Alternatively, smart meter systems that use processors and software can record energy flow accurately, calculate the exact costs of power usage and automate energy export.
The electricity industry has voiced fears that microgeneration on a large
scale would create unacceptable voltage fluctuations on the distribution grid.
The grid was, after all, designed to transmit electricity from power stations through substations to the low-voltage cables that connect homes. It was not designed to receive power from a large number of small sources.
Yet according to a report in 2004 by consultants Mott MacDonald, such fears
are unfounded, in the
Most microgenerators are not yet the simple-to-install consumer products that advocates hope they will become. Micro-CHP must show that it is reliable, for instance. And the manufacturers of small wind generators will have to convince the public that they have eliminated the noise that many people still see as a problem with wind turbines.
Crucially, the prospects for microgeneration depend on how quickly the cost of installing the equipment can be recouped. Utility bills tend to track the price of oil, so last year's sharp rise in the oil price should improve the economics of microgeneration. A micro-CHP system will now pay for itself in about 12 years, a small wind or water turbine in slightly less. But it still takes around 50 years for most photovoltaic systems to pay for themselves.
At the root of the problem is the obstacle that often faces new
technologies: production runs for domestic power generators are still small, so
individual units are expensive. The EST report suggests that governments could
help by subsidising the cost to consumers, and introducing a requirement that
all new buildings should include microgenerators. Yet
Microgenerators can harness energy from sources ranging from natural gas to
the sun's rays. But in the
Two of the rooftop wind turbines undergoing trials in the
The 1.75-metre Windsave turbine produces 1 kilowatt in winds of 12 metres per second, and trials of it are being backed by British Gas. Key to the design is that it simply plugs into a standard mains socket. An inverter converts the output from the turbine into 230 volts AC, and a sensor adjusts the phase of the output to match that of the mains. "It's counter-intuitive," says Walt Patterson of Chatham House. "You plug it in to generate electricity." Both turbines are expected to cost about £1 per watt to install and could pay for themselves in eight years or so.
The outlook is less bright for photovoltaic panels. Global PV capacity is doubling
every two years, but less than a quarter of existing PV installations are
economic, and only pay off where there is no mains electricity. The Eddystone
lighthouse off the coast of south-west
Microgeneration is not just about generating electricity: you can make your
own heat too. One option is to extract heat from the ground using a heat pump
that pulls heat out of a mixture of water and antifreeze flowing through a
closed loop of pipes laid in the ground. Ideal for underfloor heating, heat
pump systems are already as cheap as oil-fired central heating. Solar heating
is also widely used to provide hot water - and not just in sunny locations like
the Mediterranean and southern