The following are the main types of renewables to consider (costs are approximate and based on summer 2008 prices). Prices vary considerably from site to site and between models: Solar hot water panels, Photovoltaic cells, Wind turbines, Mini-hydropower, Heat pumps, Biomass boilers.
Solar hot water panels. These are panels that use the sun's energy to heat water. They are generally roof mounted and oriented in a southerly direction. They are relatively cheap, easy to install and a very effective renewable. The panels work alongside your existing system, but they should still be effective in low light levels, during the summer months householders have little need for their boiler or immersion heaters (and just use these to top up the hot water from time to time). For supply and installation, expect to pay £4,000 plus (a £400 grant may be available).
The Solar Trade Association can provide further detail (Call 01908 442290).
Photovoltaic cells. These are solar panels that convert the sun's energy to electricity for use in your home and, if on a grid connected system, for sale to the national grid. They are generally roof mounted and oriented in a southerly direction. If you are planning to replace your roof, they can come as special tiles.They can be costly, depending on how many you want, but are very effective and increasingly efficient. They will work the whole year through, even on cloudy days, but they will have a lower output in the winter months when there are less daylight hours and the sun is lower in the sky. Shading is a significant factor in the efficiency of PV systems so they must be positioned appropriately; consult installers if you need advice on this. Expect to pay £5,000 to £7,000 per kilowatts / hour, with most domestic systems usually requiring between 1.3kw / h and 3kw / h. A grant of up to £25,000 may be available under the government's low carbon buildings programme.
A working example in Mendip: Peter Macfadyen and solar power
Peter is a private householder in Frome who wanted to take serious steps to reduce his emissions. He therefore installed photovoltaic cells on his terrace town house, costing him £7000 (in 2006) after the receipt of a grant. The cells generate a maximum of 2.8KwH of energy, and his four person family have been a next exporter of electricity over the last two years. They also heat water with solar panels
Motivation: Predominantly environmental. Peter is very concerned about climate change and greenhouse gas emissions and wanted to do something substantial to reduce his own emissions. There was also a financial motivation, in that if you have the money to invest: 'Putting it on the roof gives a better return than in the building society.
Practicalities: Peter secured a 50% grant for the installation of his PVs through the Low Carbon Buildings Programme and has found that, so far, they produce energy in exactly the amounts predicted. He installed as many cells as would fit on his roof and found that the use of a volt metre, allowing him to monitor his electricity consumption, has considerably reduced his energy use.
Other ways of living sustainably: Peter has extensive house insulation, has decorated with 'green' paints, grows his own organic food, cycles everywhere possible, minimises the amount of flying he does, meters all his electricity usage, and reuses and recycles everything possible. Peter founded Sustainable Frome which provides support and inspiration in and around Frome.
Wind turbines. These are turbines that convert the kinetic energy of the wind into electricity for use in your home and, if it is a grid connected system, for sale to the national grid. They vary considerably in price and performance depending on the power rating and model. They also vary in the ease of installation depending on the size and locality. In the right locations they are very effective. However, in the wrong location they can be a very poor investment. Knowledge of the wind conditions (average speed and turbulence) at your intended location and at the height at which the turbine will be mounted is essential prior to installation. Always consult the experts on the model and size of turbine before you decide what to go for.
Prices start at around £2,000 for a 1kw turbine including installation (an average house needs 2.5kw, assuming a steady windspeed of 5 metres a second).
The British Wind Energy Association can provide advice and information, telephone 020 7689 1960.
Working examples in Mendip: Cate Le Grice-Mack and wind power
Cate rans an organic and rare breeds farm in Norton St Phillip that is open to the public. She installed a wind turbine in 1997 to help meet her energy needs and in 2001 upgraded the original 2.5KW turbine to a 6KW one.
Motivation: 'real worries about global warming, I think we have our heads in the sand'
Practicalities: Very pleased with her wind turbine, after some initial teething problems it has worked well and she thinks for her location it was the best choice. She estimates the turbine will have paid for itself within the next eight years.
Other ways of living sustainably: Uses low energy light bulbs and tries to reduce energy consumption generally. Tries to eat local and organic food and minimise car use. Extensively reduces, reuses and recycles waste. She is very keen on the 'yes in my backyard' philosophy, so meeting your needs in terms of food, energy, and waste management, in your own locality.
Cate's top tip: A wind turbine maybe a nice idea but it may not be appropriate to your location and conditions.
Mini-hydropower. These use turbines that convert the kinetic energy of flowing water into electricity for use in your home. They require both flow and head (height difference). Mini-hydro power is probably the most efficient renewable if positioned in an appropriate place. Mini-hydro, unlike its large-scale counter part, is considered to be environmentally benign because schemes are usually 'run-off-river', which require little or no water to be stored. Putting any structure into a watercourse requires Land Drainage Consent from the Environment Agency, and there is a fee for this. It is always advisable to discuss any mini-hydro scheme with the Environment Agency at the earliest opportunity and prior to undertaking any work. You also need to consider land ownership, access throughout the life of the scheme and proximity of the scheme to the end user. Costs vary hugely, and depend on the site and how much power you want to generate.
The Mendip Power Group was formed in 2002 with the purpose of harnessing clean, green energy from sustainable sources using water mills and other properties on rivers in the Mendip district. Five of Mendip’s 81 mill sites are in action, four of which, with total capacity of 74kW, are exporting electricity to the grid, and another eight sites (estimated capacity of 653kW) are moving towards generating electricity from run-of-river water power. For more details, contact MPG's Chairman, Anthony Battersby, on 01373-830322.
The British Hydro Association can provide further information on micro-hydro schemes.
Heat pumps. Ground source heat pumps circulate the thermal energy naturally present in the earth. They can be used for space heating or pre heating hot water and are particularly compatible with under-floor heating, which works at a lower temperature than radiators. GSHPs require either a trench or a borehole in which the ground loop is placed. A trench is the cheapest option but has a higher land requirement. Energy return is 3 to 4 times that invested.
There are other similar technologies to consider, including air and water source heat pumps.
Heat pumps are at their most efficient in well-insulated homes. In less efficient homes, pumps will be working harder, and using more electricity. Costs start at around £10,000 for air-source pumps and are more for ground or water source heat pumps.
Contact The Heat Pump Association on 0118 9403416.
Biomass boilers. These use plant-based fuel that is burnt to produce heat. This includes conventional log burners, biomass pellet automatic feed boilers and combined heat and power stations. Not only is the fuel clean in the sense that its emissions on burning are effectively carbon neutral (provided the biomass is from a sustainable source) but you will often find that off cuts and waste materials go into the pellets, utilising otherwise wasted resources. Issues to consider include installation, which can be very expensive, and delivery and storage of fuel (pellets can be delivered in bulk in bags, or loose, but this requires a hopper which is an additional cost). Costs for supply and installation start at around £7,000.