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Turn out the lights, Isle of Wight

Don't worry if the power goes: it's Mr Green trying to save energy, writes David Derbyshire

With the click of a mouse, David Green's fridge will be switched off by a government minister several miles away. At the same time, his house lights will dim, his immersion heater will shut down and the small electric motor that powers his central heating will go quiet.

Green won't be alone. Homes and businesses across the Isle of Wight will experience similar temporary power cuts as day-to-day control of their electrical appliances is taken away.

Remarkably, they will all be delighted. Green and his neighbours are the willing volunteers in the first scheme of its kind in Britain — an attempt to cut the UK's electricity needs by getting ordinary households to reduce demand for 20 minutes or so when required.

This first demonstration — on October 17 at a ceremony in Cowes — will involve just a few homes and businesses, but it will be followed by a full trial involving up to 1,000 homes by the end of the year.

This extraordinary idea is at the heart of ambitious plans by Green — the appropriately named founder of the community-run business Ecoisland — to make the Isle of Wight selfsufficient in renewable energy within eight years.

In exchange for their sacrifices, homes and businesses taking part in the full trial will receive financial incentives and see annual fuel bills slashed. If it works, the scheme could be copied across Britain.

The experiment is the first serious attempt to let ordinary homes join the electricity balancing market — a trading system that ensures demand for electricity matches supply.

Demand varies hugely through the day, the week and the year. It peaks in winter evenings, reaching about 55 gigawatts (GW) at 5.30pm when Britons start arriving home from work to make supper and before commercial users have shut down fully for the night. It slumps to about 35GW at 4.30am in summer when most of us are tucked up in bed.

If the supply from power stations and wind farms exceeds demand, the national grid experiences overload, causing circuit breakers to trip and wreck electronics, plunging streets into darkness. Too little electricity in the system can be just as disastrous, with the potential to trigger blackouts.

The troughs and spikes in demand are predictable. National grid forecasters work around the clock drawing on weather forecasts, TV listings and historical records to plan for the next few hours and days. They keep an eye out for sudden changes in weather, power station faults and laterunning football matches on TV to make sure supply matches demand.

The national grid can increase supply by switching on hydroelectric power stations or importing electricity from overseas.

It cuts supply by paying wind farms and other generators not to connect to the grid. It can also balance the grid by asking big consumers to reduce demand. Large factories and steelworks have contracts with the national grid under which they power down, often at a few moments' notice. The contracts between the national grid and suppliers and consumers make up the electricity balancing market, worth up to 600m a year.

For environmentalists such as Green, using demand management makes more sense than cranking up another gasfired power station. But he does not just want big factories switching off — he wants to see thousands, maybe millions, of homes volunteering to cut consumption at times of need in exchange for a cash incentive.

"On October 17, we are going to start with a small number of houses and businesses," said Green, "but we want to get it to about 15,000 houses."

When the full scheme gets under way, participants could see savings of up to 25% on their energy bills. Some of that will come from changes in their behaviour as they learn more about their energy use. Some will come from the "remote control" switch-off of appliances and the dimming of lights.

"And they also get a share of the money that comes back because they are providing this balancing service. That could be another 10% off their bills," said Green.

The curtailment experiment will be launched at the Ecoislands Global Summit 2012, an event on the Isle of Wight bringing together 500 delegates to share information on sustainable communities. It will use a wireless "mesh" of linked boxes and controllers being created on the island by Cable & Wireless Worldwide and Silver Spring Networks.

Houses will get a home energy management system, or HEMS — a black box half the size of a shoebox that sits alongside the meter. The box talks to appliances around the home via wi-fi or by sending signals through the mains electricity. The homeowner can choose the appliances to be controlled.

Each appliance or group of lights is connected to a special plug that picks up signals from the HEMS. This allows the box to instruct the fridge to turn itself off for 20 minutes, doing no harm to the food inside, but cutting power use. It can switch off freezers, turn off immersion heaters, dim lights, shut down water fountains or put computers on stand-by.

The boxes can learn householders' habits to ensure that reducing electricity consumption is not inconvenient. The owners can over-ride the box at any time, or tell it what their status is — out, away on holiday, in but sleeping, in and awake — to ensure it doesn't switch off anything essential.

The boxes are connected to the outside world through the radio mesh of controllers placed on street lights, public buildings and telephone poles.

These controllers — called access points — are connected in turn to a central computer that monitors electricity consumption in the homes and passes on the order to cut demand when needed.

During the Isle of Wight trial, the HEMS network is being operated by Ecoisland. The organisation plans to give the network a dry run for two to three months before going live.

"It isn't without risk, because when we sign a contract with the national grid there are significant penalties if we fail to deliver," said Green.

"So we need to iron out the system to see exactly what we can do. But I'm hopeful we will be able to turn down 20MW within six months."

In the initial stages, there should be no shortage of homeowners keen to do their bit to save the planet, but difficulties may come in persuading more cynical consumers to take part.

Green believes the financial incentives will overcome concerns about big brother controlling power in people's homes. "In parts of America they went in heavy-handed with curtailment mechanisms without consent. We have a system where people get an immediate benefit if they take part."

The smart grid being used to cut demand can also be used to sell surplus small-scale renewable energy. It will also make it easier to store excess renewable energy, generated at times when there is little demand.

Surplus electricity from micro-wind technology or solar panels can be moved around the grid and used, say, to heat water in immersion tanks. After a blustery night, homes could wake up to free hot water.

Spare power can also be stored as hydrogen. The Technology Strategy Board, a funding body backed by the Department for Business, has given the go-ahead for the first commercial trial of hydrogen refuellers. The 4.6m project will use surplus renewable energy to convert water into hydrogen and oxygen. The hydrogen can be stored and used as fuel in vehicles.

Green — whose home will be part of the trial — says the island's goal of renewable energy self-sufficiency by 2020 is ambitious but not impossible.

"A lot of people have been saying, 'When are you going to be a net exporter of energy?' " he said. "On a Sunday morning recently, there was nearly 40MW of renewable electricity and we were exporting to the mainland. People think it's pie in the sky, but we have achieved it at the lowest point. The aim is to cover the peaks of demand, too."

Copyright David Derbyshire 2012