All businesses are vulnerable to fluctuations in energy prices and rely on security of supply. It therefore makes both economic and environmental sense to look at the opportunities for generating on-site energy through renewable technologies.
Solar Water & Electricity | Ground source heat pumps | Combined Heat & Power
Solar Water Heating
Although the UK is often perceived as having a climate not suited to solar power, average July solar radiation is sufficient to heat enough hot water to fill a bath. Pumped solar systems are most common in Northern Europe and consist of a collector panel (usually mounted on the roof), storage tank, and pumped circulation system.
Required capacity can be reduced by ensuring that pipes and hot water cylinders are insulated. A typical system has a life expectancy of 25 years, and produces between 1000 and 1500 kWh of heat per year.
Solar PV (Electricity)
Solar photovoltaic (PV) technology is the conversion of solar energy directly into electricity. PV cells are made from silicon, and a single cell is able to produce 1.5 Watts, so more power is obtained by grouping cells into modules and arrays.
There are two main types of cell: monocrystalline and polycrystalline. Monocrystalline cells are more expensive, but more efficient than polycrystalline cells.
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Advantages
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Disadvantages |
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Cost effective solution to energy problems in places where there is no mains electricity.
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High initial capital cost
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Silent and non-polluting
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Efficiency of cells can be affected by air pollution and adverse weather
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Little maintenance and long life-time
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Need to be protected against vandalism
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Easily installed in a south-facing roof, or can be incorporated into the actual building fabric
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Energy demand pattern needs to match sunlight availability
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Can reduce required capacity of PV by fitting reducing energy demand through improved energy efficiency
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Ground source heat pumps (GSHP) transfer heat from the ground into a building to provide space heating and, in some cases, to pre-heat domestic hot water. For every unit of electricity used to pump the heat, 3-4 units of heat are produced.
There are three important elements:
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The ground loop. This is comprised of lengths of pipe buried in the ground, either in a borehole or a horizontal trench. The pipe is usually a closed circuit and is filled with a mixture of water and antifreeze, which is pumped round the pipe absorbing heat from the ground.
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A heat pump. This takes the heat from the water in the ground loop, compresses the refrigerant to the temperature needed for the heat distribution circuit and gives up heat to a hot water tank, which feeds the system.
A typical 6 - 8kW system costs £7,300 - £11,800 plus the price of connection to the distribution system. This can vary with property and location.
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Combined Heat and Power (CHP) is the simultaneous generation of heat and electricity in a single process. CHP equipment usually burns fossil fuel to generate electricity on site. At a power station, the heat generated when electricity is produced has to be dissipated via cooling towers.
With CHP, the heat is recovered on site, and used for space heating and hot water. This means that, overall, the process is more efficient, so less fuel is used.
Micro-CHP is a miniature CHP unit designed to provide heat and power to a small building in place of a conventional boiler.
CHP is particularly cost-effective with long operating hours (i.e. ideally for at least 12 hours/day, 7 days/week) but in general, the greater the annual period of demand, the higher the cost savings. There should be reasonable confidence in the future demand for heat and power over the lifetime of the CHP plant, typically 10-15 years.
Providing the site energy usage is sufficient, generating electricity locally using a CHP plant will normally be a cheaper than purchasing electricity from a conventional supplier. It increases security of supply, especially in remote locations or where the power supply can be interrupted.
For more information on renewable energy technologies, contact:*
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