Supply and Demand:
Hampton Lucy census (2001) - key statistics:
Resident Households: 204
Average Household Size: 2.50
- Lone Person - 42 (20.6%)
- Lone Pensioner - 19 (9.3%)
- Married - 98 (48.0%)
- Co-habiting - 9 (4.4%)
- Lone Parent - 12 (5.9%)
- With dependent children - 4 (2.0%)
- With non-dependent children - 8 (3.9%)
- Other - 15 (7.4%)
- Detached - 91 (42.3%)
- Semi-detached - 96 (44.7%)
- Terraced - 28 (13.0%)
[Source: Warwickshire County Council Census (2001) ]
The nPower Renewables site reports an average household electricity usage of 4700kWh per year:Household consumption figure of 4,700 kWh calculated by dividing UK domestic electricity consumption for the year 2003 by the number of households counted in 2001 National Census.
Therefore converting this down gives a value of 0.54kW per hour. Assuming that our micro-hydro scheme will have an approximate output of 20-30kW and an efficiency of 60%, we will be outputting around 12-18kW of useful power. Therefore at best we be able to supply about 33 houses, and at worst 22 houses, if we were to fully supply electricity to each house. If the electricity output were to be spread between all the houses in the village, this would result in somewhere between 58W and 88W each (i.e. almost insignificant, except for the moral factors involved).
If we were to sell electricity to the national grid at 2.5p per kWh (a rough guess as to what we might be able to get), then we would be making approximately £4000 per year at maximum output. If the cost of the scheme is £50000 then this gives a payback time of 12.5 years. These numbers are mostly rough estimates of what it might cost, and will be replaced with more accurate values once they are obtained.
[Source: nPower Renewables ]
This value of 0.54kW per hour seems low, and it is much more likely that the value should be around the 5kW+ area. Therefore we're only going to be able to supply 3 or 4 houses at best, which makes the idea of supplying electricity directly to houses a bit unjustified. There are, however, some very good reasons to supply directly to the national grid. I have confirmed that the price for the sale of electricity is between 2 and 2.5p per unit (kWh) for low usage areas, and between 3.5 and 5.5p per unit for high energy usage areas. Hampton Lucy is likely to fall into the first category, and so the £4000 income calculated above may not be far off the actual income (assuming the power generated is accurate).
In addition to this, it is possible to claim a Renewables Obligation Certificate (ROC) for every megawatt hour (MWh) of power generated. These certificates are required by companies as proof that they are meeting targets set out by the government to produce energy through renewable sources. When a company does not meet it's target (which is often the case) they must buy ROCs to make up for the difference. Therefore by gaining an ROC through the generation of power at our site, it can then be sold on to electrical suppliers in need. These certificates have a price at around £30 (~3p per kWh).
There is one final method of increasing the income from the project, which can be used in conjunction with the previously mentioned methods. Again, this is another form of certificate known as a Levy Exemption Certificate (LEC), and can be used to to avoid the Climate Charge Levy which is added to the cost of electricity for businesses. This added tax is valued at 0.43p/kWh, and the LECs can be sold for up to 90% of their value.
[Source: British Hydro Association ]