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May 6, 2011
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Combined Heat & Power

Combined Heat & Power

Forms of power generation using combustion can generally be made more efficient if the surplus heat is captured and used too. This is called Combined Heat and Power (CHP).

In conventional power generation the large amount of heat produced as a by-product is lost. Combined Heat and Power technology puts this heat to use, recycling it for use in community heating or for industrial purposes. This makes CHP a much more fuel efficient method of power generation, increasing overall efficiency of fuel use to more than 75% compared with the 50% achieved by conventional power generation.

A variety of fuels can be used to power a CHP generator, as well as fossil fuels these include renewable sources such as Biomass, Geothermal and Solar Energy.

A CHP plant consists of one or more prime movers, such as a reciprocating engine, gas turbine or steam turbine which drives an electrical generator. The steam or hot water generated is then used rather than wasted.

CHP plants are generally smaller than electricity plants and are usually attached to a site that consumes all or most of the heat and power it produces.

High capital and maintenance costs mean CHP is more often used by the industrial, commercial or public sector rather than individual domestic users. It is popular with those requiring large amounts of heat, such as hospitals and leisure centers. As the plants generally supply electricity locally they also avoid transmission and distribution losses associated with conventional electricity supplies.

The increase in fuel efficiency means Combined Heat and Power is playing an increasingly important role in reducing carbon dioxide emissions, achieving reductions of as much as 50%.

Converting to Combined Heat and Power also lowers emissions of sulphur dioxide and nitrogen oxides, reducing acid rain.

May 6, 2011
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Solar heating

Solar heating

Active solar heating systems convert solar radiation into heat which can be used directly.

In the Albania uses are primarily domestic water heating and other low temperature heating applications. In hotter climates a wider range of applications is possible, including electricity generation.

There are two types of solar water heating systems, Direct and Indirect. With Direct systems the water flowing in the collector tubes is the same as the water circulating in the tank and comes out of the taps, With Indirect systems the heat transfer fluid circulating around the system does not come into direct contact with the water coming in the tank or coming out of the taps.

Domestic water heating schemes consist of solar collectors, pump, control unit, connecting pipes, and backup heat source such as gas or electric immersion heater. With Direct hot water system, the existing hot water tank can be retained. However for Indirect systems, if the existing hot water tank is to be retained a pre-heat tank will be required. Alternatively the existing single coil hot water tank can be replaced with a twin coil tank removing the need for a preheat tank.

The overall area of the panels is typically 3-4 square meters.

Renewable electricity generating technologies such as photovoltaic’s and wind turbines can be used to offset the small amount of carbon emissions arising from the electric pump circulating water around the solar hot water system.

 

May 6, 2011
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Heat pumps

Heat pumps

These are devices that can extract and amplify heat obtained from a source of thermal energy.

There are several types of heat pump. All use the same basic principle of extracting heat from a source and concentrating it to obtain a higher temperature, usually then applied to water for domestic heating and hot water.The device which does this can be thought of as a refrigerator operating in reverse. It is powered by electricity, but the amount of heat energy delivered is several times more than the electrical energy consumed. The ratio of the output to the input energy is called the Coefficient of Performance (COP).As heat pumps transfer rather than produce heat they are more efficient than traditional heating systems.

Ground source heat pumps

Obtain their heat energy from the ground. The temperature of the soil even just a meter down is very stable throughout the year in the UK.The ground heat is captured using water passed through pipes buried in the ground. These can be either coils buried in the topsoil, or one or more boreholes sunk deeper into the subsoil.

Air source heat pumps

Obtain their heat from the ambient air, using a fan unit located outside the building. The pump converts heat from the air into more useful energy through a heat exchanger.Air source heat pumps can save more than 2 tons of carbon a year, emitting 50% less than gas boilers and 70% less than electric systems.As well as being used to heat in winter their cycle can be reversed to cool in the summer, when the unit takes heat out of the indoor air and releases it outside.

Water source heat pumps

These are rather rarer, using heat from a pond, lake, river stream or other body of water, to provide heating for nearby homes.The water is drawn in to the pump’s heat exchanger, where the heat is extracted and the water is returned to the source.

May 6, 2011
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Woodfuel for heat

Woodfuel for heat

What is Woodfuel?

Woodfuel for heat is woody fuel that is burned to generate energy for space heating or hot water.

Woodfuel includes logs, woodchip or pellets to be used in applications ranging from an open log fire or a woodburning stove to modern, sophisticated boiler systems.

Modern woodchip or pellet boilers are highly efficient, convenient and low maintenance, usually with automatic fuel handling, loading and ignition systems and thermostatic controls.

Why is it a renewable and low carbon fuel?

Woodfuel is stored solar energy that can be re-grown in a matter of years, unlike fossil fuels which are a finite energy resource. Woodfuel is also carbon neutral at source.  Burning wood simply releases the CO2 that was absorbed during the trees growth, keeping the level of carbon at an equilibrium.


The benefits of woodfuel heat

Apart from being a renewable and low carbon fuel woodfuel has a number of other benefits.

Cost efficient

Renewable heat is the lowest cost renewable option for meeting our 2020 renewable energy targets. The renewable heat sector has a 12% proposed contribution to make by 2020 (from 1% today). If this is met 60 mt of CO2 would be saved at 90-155 Euro/tonne of carbon saved. Within the renewable heat sector woodfuel for heat is by far the cheapest renewable heat source .

Low greenhouse gas emissions

As explained above woodfuel is carbon neutral at source. Woodfuel offers 80% or more lifecycle greenhouse gas savings, compared to fossil fuel alternatives.

Efficient use of fuel

Woodfuel for heat offers 85% typical efficiency.

Energy Security

Woodfuel can be sourced locally, from within the Albania, reducing reliance on unstable supply chains.

Local Jobs

A healthy woodfuel supply chain requires a skilled workforce. New market opportunities benefit communities by stimulating local economies, creating new jobs and diversification.

 

May 6, 2011
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Geothermal heat

Geothermal heat

Heat from the hot core of the earth can be extracted and used in various ways (including ground source heat pumps described separately)

Hot dry rocks

One form of geothermal energy is produced using hot rocks, a few kilometers beneath the earth’s surface. Water is pumped into this hot, crystalline rock using an injection well. As it flows through fractures in the rock the water heats up and is returned to the surface through another well, known as a production well. At the surface the heat is extracted from the water and using a steam turbine, generates electricity. The water is then recalculated to mine more heat.

Geothermal energy not only has little impact on climate or the environment but it is also clean, quiet and virtually inexhaustible. One cubic kilometer of hot granite at 250 degrees centigrade is said to have the stored energy equivalent of 40 million barrels of oil.

Hot dry rock (HDR) energy is increasingly becoming an important source of energy but only a small number of locations currently have the right conditions for cost effective production. The granite rock must be no deeper than 5 kilometers, the current capability of drilling equipment, and it must be covered by around 3 kilometers of insulating rock which prevents the heat escaping to the surface.

Geothermal aquifers

Unlike hot dry rocks, where water is pumped through the underground rocks, an aquifer is an underground layer of permeable rock in which water already naturally occurs. As the hot water flows through the rock it can be extracted using a borehole.

Water temperatures between 50 and 150 degrees centigrade can be used for heating and higher temperatures are used to produce electricity. Those areas with the best geological conditions for producing electricity usually occur close to crustal plate margins.

After the heat has been extracted the cooled water is then pumped back into the ground. Whilst geothermal aquifers are not completely renewable as heat is usually extracted at a rate quicker than it is replenished by the surrounding rocks, geothermal energy is much less environmentally damaging than fossil fuels.

Geothermal power plants emit 1000-2000 times less carbon dioxide than fossil fuel power plants and take up a much smaller area of land.