Powergen's CHP (Combined Heat and Power) Generation

Responsible, sustainable use of our planets resources is playing an increasing role in the development and planning of tomorrow’s world. It appears guilt, media coverage and the realisation that we simply cannot continue in our current manor, is fortunately, generating this noticeable push for change. The degree of irreversible damage and its effect on the earth’s stability is certainly worrying, to say the least. It is undoubtedly everybody’s responsibility. However governments and such organisations have the added ‘duty’ of offering products and incentives to guide the general public into eco-friendly ways. There are literally millions of technologies capable of helping to form such a revolution, below and in the following assignments I will introduce, analyse and review one: Combined heat and power (CHP).

CHP: Where systems simultaneously generate electricity and heat in one process.
This relatively simple concept utilises the main by-product of energy generation (heat) by piping unwanted warmth into inhabited spaces, rather than releasing it into the atmosphere.

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Mass systems have been installed at power stations within Denmark, Finland and across England in Yorkshire, Kent, Liverpool and Cumbria amongst others. However CHP on such a scale brings problems, the biggest being transport. Expensive super insulated piping has to be laid and maintained in order to move heat into residential areas. Bringing the obvious question: How can this system become widespread when there are millions of houses situated more than a few hundred metres from such a power station?

In October 2003, the BBC reported on Powergen’s micro CHP product, WhisperGen. A single unit roughly the size of a washing machine, which is fitted into residential dwellings and is capable of producing hot water, heating and electricity.

The boiler utilises the principles of the Stirling engine, invented by Robert Stirling in 1816. “There's a gas burner at the top. It heats up four cylinders, each of which contains nitrogen gas and a piston. The gas expands as it warms up, pushing the pistons down. The pistons are cooled on the central heating water, which passes underneath, so they go up again. Pistons which go up and down 1,600 times a minute, turning a generator and producing a constant supply of hot water.” The user is kept informed of progress with a simple LCD interface displaying data such as the current water temperature and the level of energy being produced.

The unit produces enough energy to run standard non ‘power-hungry’ devices, but if a kettle is switched on for example additional power is simply taken from the national grid. A major plus is when surplus electricity is created, as the unit automatically pipes energy straight back to the grid under its ‘buy back’ agreement.

It is estimated users can realistically achieve a 20% saving compared to the present-day setup where electricity and water/ heating are produced independently. Powergen issued 400 units to houses in the Midlands, East Anglia, Yorkshire and the North West in 2005. With a planned 80,000 in the years to follow. The company also claimed 30% of householders will be utilising the micro CHP technology by the year 2020.

The assignments following this initial introduction will delve into CHP further, evaluating the following points:
- Does it appear feasible to continue, what have been the main obstacles?
- How widespread is CHP?
- This technology does use gas more efficiently, however this is still a non-renewable fuel, are there alternatives?
- Would a CHP unit generating energy at a street/ village level be more efficient, would could be the associated problems?
- Has the buy back scheme worked, is it fair?
- How could the success of WhisperGen be accelerated?