Frequently Asked Questions
Frequently Asked Questions
Combined Heat and Power (CHP)
Q. What is Combined Heat & Power? A. Combined Heat and Power (CHP) is the simultaneous generation of usable heat and power (usually electricity) in a single process. CHP systems can be employed over a wide range of sizes, applications, fuels and technologies. In its simplest form, it employs a gas turbine, an engine or a steam turbine to drive an alternator, and the resulting electricity can be used either wholly or partially on-site. The heat produced during power generation is recovered, usually in a heat recovery boiler and can be used to raise steam for a number of industrial processes, to provide hot water for space heating. Q: How efficient is CHP? A: Because CHP systems make use of much of the heat produced during the electricity generation process, they can achieve overall efficiencies in excess of 70%. In contrast, the efficiency of conventional coal-fired and gas-fired power stations, which discard heat produced during electricity generation, is typically around 38% and 48% respectively. Q: What is district heating? How does it work? A: District heating (sometimes called community heating) is where one central boiler provides heat to several buildings. These might be blocks of social housing, local council offices, a school, etc… District heating can be provided using the co-generated heat from electrical power generation in a Combined Heat and Power (CHP) installation. This can increase the overall efficiency of power generation by a factor of three or more. Hot water or steam is transferred around the site in a highly insulated heating main. Each building then has an individual heat exchanger to draw off the heat into the building as required. District heating is much more common in some European countries than in the UK. In Denmark for instance district heating provides around 60% of heating.
Woodfuel Heating
Q: What is woodfuel heating? A: This is a type of heating that involves burning biomass such as wood pellets or chips in a ‘boiler’ unit to produce heat. In domestic settings, these units can be space heaters such as stoves but higher output boilers can also provide hot water or central heating via radiators. Boilers are quite sophisticated now, and can be fed automatically by screw drives from fuel hoppers. Electric firing and automatic de-ashing are also available. A: Most renewable energy production is focussed on producing energy in the form of electricity. Heat is also a form of energy. Heat currently accounts for 49% of the UK's final energy demand (BERR 'Energy Trends' December 2007, HMSO), most of which is used to heat households. By producing your own heat from burning wood, not only are you are using biomass in a highly efficieny way, but you can reduce central heating bills, avoid rising gas or electricity prices and reduce your carbon emissions. Q: Can I use biomass heating in a smokeless zone? A: Yes: Biomass appliances with an exemption certificate can be used in smokeless zones, and the majority of woodfuel boilers are fine to install in smoke free areas. See www.uksmokecontrolareas.co.uk for a full list of exempt appliances. Q: Why can I use a biomass boiler in a smokeless zone? A: Wood fuel boilers run at a very high efficiency (90%+), which means that the wood fuel is converted into heat with very few smoke particles produced. Q: Are there any grants available? A: Grants are available to install biomass boilers. Different grants are available depending on your situation. See the Grants sectionon the website for further information. The most appropriate grant for domestic biomass boilers is called the Low Carbon Buildings Gran, for information see: www.lowcarbonbuildings.org.uk/home Q: Do I need planning permission to install a domestic biomass system? A: If the building is listed or in an area of outstanding natural beauty (AONB), then you will need to check with your Local Authority Planning Department before a flue is fitted. Q: What is the cost of installing a biomass boiler? A: The cost for boilers varies depending on the system choice; a typical 15kW* pellet boiler would cost around £5,000 - £14,000 installed. * 15kW is the average size required for a three-bedroom semi detached house Q: How much do the pellets cost? A: Unlike other forms of renewable energy such as wind or solar power, biomass systems require you to pay for the fuel. Pellets typically cost between £120 - £180 /tonne and pellets cost less at £50 - £80 /tonne. Fuel costs also depend on the distance from your supplier and whether you can buy in large quantities.
These heaters can be almost any size, ranging from a small 15kw unit that will heat a private house, to large scale units suitable for heating factories or large buildings, such as the 700kw boiler that heats Worcestershire County Hall.
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