Wind, sun, earth or water: greener ways to fuel home

Reducing your contribution to climate change doesn't have to mean putting on a hair shirt. While giving up air travel will reduce the size of your carbon footprint, when it comes to home energy - a more likely source of excessive carbon dioxide emissions for most families - a happy by-product of doing your bit for the environment is a potentially handsome financial dividend.

Energy efficiency week begins on Monday. Promoted by organisations such as the Energy Saving Trust and the Energy Retail Association, this annual initiative encourages people to reduce their home energy consumption.

"The average UK home releases more than six tonnes of carbon dioxide each year, when its energy comes from power stations burning fossil fuels," says a spokesman for Energy Future, the environmental power adviser.

"By generating energy from renewable sources, you will help protect the environment, reduce carbon emissions and be more energy self-sufficient - you may also be able to sell the electricity, if you are connected to the national grid."

Installing a renewable energy system - solar, wind, ground-heat or water-based - is a major financial commitment, but the Government's low-carbon buildings programme offers quite generous grants. To qualify, your home must already have basic energy-saving devices installed - insulation and energy-efficient lightbulbs, for example. You must also use a registered renewable energy company to manage your project.

In return, the grants can be very valuable. They vary according to the type of energy you're installing and the amount of power it can generate. For solar electricity, for example, you can claim £3,000 for each kilowatt of power the system will produce, up to a maximum grant of £15,000 or 50 per cent of the cost of the project.

There are, however, practical problems. "This is still very much an emerging market," says Mat Colmer of the Energy Saving Trust. "Prices are coming down, but we're still in the realm of 'early adopters'."

One issue is planning permission. While local authorities are now likely to give the go-ahead to most solar installations - conservation areas and listed buildings excepted - wind is more difficult.

"Local authorities are becoming more receptive, not least because they have their own renewables targets," says Colmer. "But 'nimbyism' is still a problem and people often object to neighbours' applications for wind turbines."

It can also be difficult to find a qualified installer. The number of companies accredited under the low-carbon buildings programme is rising, but still limited.

Despite these problems, however, it's worth pushing ahead. And although environmental issues have become sufficiently fashionable to sustain an increasing industry of professional advisers, offering services such as green makeovers for your home, there is plenty of free advice on offer.

The Energy Saving Trust Advice Centre (call 0800 512 012 for your local office), for example, offers personalised audits of your home energy usage.

Useful contacts: Energy Saving Trust: www.est.org.uk; Energy Future: www.energyfuture.gov.uk; Energy Retail Association: www.energy-retail.org.uk; Energywatch: www.energywatch.org.uk; National Energy Foundation: www.nef.org.uk.

SOLAR POWER

How it works: Two different technologies enable homeowners to harness the sun's power to produce hot water and electricity. Solar water-heating systems use solar panels to collect heat that is then used to produce your hot water, usually in tandem with your existing heating. Solar electricity systems use photovoltaic cells to convert solar radiation into electricity.

What you'll need: In both cases, you'll need several square metres of south-east to south-west facing roof or wall space that is strong enough to hold the panels or cells and is not overshadowed by other buildings or trees. You may have to get planning permission for the equipment, so check with your local authority. Water-heating systems may require the installation of an additional cylinder.

What it costs: Expect to pay between £2,000 and £3,000 for a basic water-heating system. Maintenance should not add more than a few pounds, with most systems covered by a 10-year warranty. Installing a photovoltaic system is more expensive - anything from £6,000 to £18,000. Systems wired into the mains grid - the usual set-up - are cheap to maintain, though standalone systems may need more work.

Payback: Solar water heating should meet all your hot-water needs during the summer, and up to half your requirements over the winter, reducing your heating bill by 75 per cent. You'll also cut CO2 emissions by an average of a tonne a year. Solar electricity is generally fed back into the mains grid, reducing your electricity bill by £125 a year.

WIND TURBINES

How they work: People have been harnessing the power of the wind for several hundred years and the UK has 40 per cent of Europe's total wind energy. Modern microturbines are suitable for installation in many homes and convert wind into electricity that is fed back into the mains grid.

What you'll need: Wind speed increases with height, so the higher you can mount your turbine the better. You may need to take specialist advice on whether local wind patterns are sufficient to make the project worthwhile. If you're planning to generate electricity that will be fed back into the mains grid, you'll need a system that converts the power generated into a suitable standard. If not, you'll need a back-up system for times when the wind is not blowing. A turbine will usually require planning consent.

What they cost: A small turbine system capable of generating 1kW costs around £3,000. Larger systems - up to 6kW - could cost as much as £18,000.

Payback: The typical domestic system generates around 2.5kW. For a cost of around £12,500, expect to save £250 a year on electricity bills and cut emissions by up to two tonnes.

GROUND SOURCE HEAT PUMPS

How they work: The ground several metres below your home is at a constant temperature all year round - typically about 12C - whatever the weather. You can use this to heat your house and also to warm up water. The system incorporates a ground loop, a heat pump and a heat distribution system, usually underfloor heating and water storage.

What you'll need: Plenty of land for a trench or borehole to bury the ground loop. You may also need to improve the insulation of your home. Finally, while ground-source heat will work with existing radiators, underfloor heating is more efficient.

What they cost: Expect to pay between £6,500 and £9,500 for the system itself, plus an additional sum to connect up the distribution system - more if you need to install underfloor heating. Installing the system as part of a new build is likely to be cheaper.

Payback: Ground-source heating will save money for people using oil or electricity to keep their homes warm - as much as £750 a year - though gas is marginally cheaper. Your carbon emissions fall by up to 5.5 tonnes a year because you are no longer burning fossil fuels, though you will need some electricity to power the system. To be 100 per cent renewable, this would need to be solar generated or at least bought through a green tariff.

HYDRO POWER

How it works: You can generate usable electricity from even a small stream, so hydro power may suit anyone with water flowing across their land. If you don't have this option, it is possible to form a community project - a local river might be a possible source of power. Your own hydro system can be set up on a standalone basis, or connected to the mains grid.

What you'll need: At the very least, you'll need water. The energy it can generate will depend on how fast it flows and the height it flows at. A small system might be able to capture 50 per cent of this power, with the electricity then used for lighting, power and even heating. You will probably need planning consent.

What it costs: The initial capital spend is likely to be high - around £4,000 for each kilowatt of power produced, although costs will vary hugely. A typical domestic system could cost as much as £25,000.

Payback: What you'll make back also varies hugely, but the more powerful systems could cover all your electricity needs. That would substantially reduce your carbon emissions, but there are other environmental issues to consider. A water turbine may be noisy and could affect the ecology of your water source.

Five cheaper ways to cut your energy bills and save the environment

* Insulate everywhere: Insulating is the most effective way of reducing the amount of heat your home loses. Potential saving: £80 a year (more if your power company offers grants towards the cost of insulation).

* Boil carefully: Stop over-filling the kettle each time you make a cup of tea. Potential saving: £5 a year.

* Drive efficiently: Turn the engine off if you are stationary for more than a minute, removeroof-racks and accessories, check tyre-pressures, and drive more smoothly. Potential saving: £120 a year.

* Wash warmly: Reduce the energy used when doing the laundry by nearly half by turning the dial to 30C. Potential saving: £9 a year.

* Save light: Change your ordinary light bulbs for energy-saving ones. Potential saving: £9 a year for a 100W bulb, or £100 over the bulb's lifetime.

Keith signposts the way to the future

Six years ago, Keith Thomson had two solar panels installed on the roof of his home in Bradford. "I wanted to set an example and show that these things can be done," he says. "People see the panels and it's a talking point - they are signposts to the future."

The panels make a significant contribution to the energy required to heat water for Keith and his family. In the summer, most of their hot water is generated by solar energy - at other times of year, there is enough energy to warm up water, so that less energy is required to make it hot. "Even on the murkiest of days, we get some use from the panels," Keith says.

However, while Keith is delighted that the panels have reduced his family's energy consumption and their impact on the environment, he warns people to be wary about the returns that are sometimes advertised for renewable energy.

"We've certainly made savings on our heating bills, but it will be a good few years yet before we recoup our initial outlay," he says.

New convert puts faith in the wind

Two years ago, Christine Griffiths bought a grade 2-listed Gloucestershire farmhouse, and was shocked when the electricity bills began arriving. Her first plan was to use solar technology to reduce the farm's energy consumption, but her local authority said the building's listed status precluded the installation of panels of photovoltaic cells. It was then that she began investigating a wind turbine.

By the end of last year, work on a 9m wind turbine in Christine's orchard had been completed. When the wind blows well, the turbine can produce 6kW of power an hour, easily enough to make the farm self-sufficient. Excess electricity is sold back to Christine's local electricity company, through the normal mains grid connection. She also buys power when the turbine is not producing enough.

"We paid around £18,000 to install the turbine, but we got a £5,000 grant from the Government towards that cost," Christine says. "We reckon we'll break even in 10 years or so, but if we sell up before then, the drastically reduced electricity bills we now have would be a major selling point."

Christine has become such a convert to wind power that earlier this year she launched her own company Aqueous Power, which installs wind turbines across the South of England. Christine believes wind power is currently best-suited to rural locations, but expects new technology to make turbines possible for city dwellers soon.

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