Renewable Energy Sources & CHP – Combined Heat & Power Systems
RENEWABLE ENERGY SOURCES & C.H.P:
New ‘Renewable’ technologies are becoming more popular as a means of providing some (or all) of the heating & / or hot water from renewable energy sources. At this point in time the capital cost of fitting such heating systems is significantly higher than a conventional boiler-driven system, and in most cases a boiler is also needed to supplement the operation of the renewable energy source. Looking to the future, as these systems are produced in larger numbers and with seemingly inevitable rises in fuel costs likely over coming years, the ‘payback’ time on the installation of renewable energy sources should gradually reduce, making them more financially attractive.
Solar Heated Hot Water
Solar Panels can be fitted on a suitable roof (preferably South facing) and these are connected to a coil inside a special hot water storage cylinder which heats the domestic hot water from the solar heat. A second heating coil in the cylinder is connected to the normal central heating boiler and a sophisticated control system only brings the boiler into to play when insufficient heat is being generated from the solar panels.
Heat is generated by the solar panels all-year-round, obviously more is generated in summer when the sun is warmer and there are longer hours of daylight, but the solar heating system still works even when the sun is behind clouds and the solar panels can supply around 70 – 80% of a typical household’s hot water demand over a year, possibly saving up to £150 per annum in fuel bills.
Heat Pumps (Air Source and Ground Source)
A range of ‘Heat Pump Systems’ are becoming available to provide central heating and hot water. In most cases a (smaller then usual) conventional boiler is used to supplement the heat pump system when weather is cold.
There are two basic types of Heat Pump System:
Air source heat pumps absorb heat from the outside air to heat buildings (these will still work well with sub-zero exterior temperatures). There are two types of air-source heating systems. Air-to-air systems provide warm air, which is circulated to heat the building. The other type, air-to-water, heat water to provide heating to a building through radiators or an underfloor system.
Ground source heat pumps use a buried ground loop which transfers heat from the ground into a building to provide space heating and, in some cases, to pre-heat domestic hot water.
Micro CHP (Combined Heat and Power)
Combined Heat & Power Systems are now becoming available. These simultaneously generate usable heat and electrical power in a single process. They are suited for use in single dwellings, and range in size from around 4kW heat output (suited to small, well insulated dwellings) up to about 36kW (these units will incorporate a supplementary boiler for additional heat output in larger dwellings).
The electrical power output of these CHP (Combined Heat & Power) systems is typically 1kW to 3kW and is grid-connected, so that when you need more power than the unit produces it is automatically ‘topped-up’ from the mains. It is also possible that any surplus power generated by the CHP system may be sold back to your electricity supplier. Unit cost of installation is expected to be between £2,500 and around £3,500 plus any work which may be required to the heat distribution network and electrical system. The typical fuel cost savings of CHP (Combined Heat & Power) systems could be approximately £150 a year compared with a conventional gas-fired boiler.