From Greenhouse to Green House

The threats of climate change
CO2 emissions and savings


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Until recently, this seemed like the easy bit. We bought our electricity from Good Energy which seemed to mean that it all came from wind power, hydroelectricity and to a lesser extent, biomass. So we thought we were entitled to claim that all our CO2 emissions from electricity consumption have been reduced to zero as shown on our spreadsheet of CO2 emissions.

However, Good Energy receives 'Renewable Obligation Certificates' (ROCs) from the Government for the green electricity it sells and, since it gets many ROCs more than is required by law, it can sell these to other companies that are falling short of the legal minimum. Although Good Energy 'retires' about 10% of its surplus ROCs (takes them out of circulation), it sells the rest and that means, in effect, that the electricity that it supplies is less green than it appears superficially. For this reason, we are not claiming that our electricity is 100% renewable.

As described in an article in the Ecologist, the issues are complex. In general, it seems that the ROC system is flawed. It protects electricity suppliers that are doing little to switch to green sources of electricity and makes it virtually impossible for any customer to buy truly 100% green electricity. We believe that a much better system, with far fewer contradictions and anomalies, is the Kyoto2 system for controlling emissions of greenhouse gases or Personal Carbon Allowances.

Low energy bulbs

Most of the lights in our house are low-energy versions that consume about one seventh of the electricity of traditional light bulbs. We have some ceiling lights and two wall lights that will only take ordinary bulbs. From time to time, we look for new light fittings for these locations but we have not yet found any that are designed specifically for the low-energy light units. It would be good to see some new designs in the shops.


This is an option but it looks as if prices will have to drop quite a bit for solar electricity to compete with supplies from companies like Good Energy or Juice. Some kind of system for storing energy or an alternative supply is needed for evenings and other times when the sun does not shine (the energy-storing technology being developed by Wind Hydrogen Ltd could be useful here).

New technology from Nanosolar promises lower prices and greater flexibility in where solar panels can be installed. New technology from SunPower promises lower prices. Other interesting developments are H-Alpha Solar flexible and cheap solar panels and similar panels from Flexcell.

Links: UK Government grants, Solar Century, British Photovoltaics Association, How solar cells work.

Combined heat and power

There are some signs that the Government may promote combined heat and power (CHP) - electricity generation in small local units (perhaps individual houses or flats) where waste heat from the generator is used for domestic heating. Compared with traditional methods of generating electricity and providing domestic heating, CHP can mean substantial savings in CO2.

Until recently, it has not been easy to go out and buy a CHP unit for the home. Now Powergen have introduce Whispergen, described as micro-CHP.

There is a good article in the New Scientist, 2nd March 2002 (No. 2332), pp. 36-38.

Links: WhisperTech, Whispergen.

Micro wind turbines

There is growing interest in generating electricity using small-scale wind turbines near the buildings that use the electricity or even mounted on the buildings—but wind speeds must be quite high to justify the investment and most people live in situations where there is not enough wind.

Links: AirDolphin, Windsave, Renewable Devices Swift Turbines, Proven Energy Ltd, Segen small wind installations

Concentrating solar power

This is not currently available as a source of electricity in the UK but it has huge potential as a versatile source of energy for the whole world.

Dynamic demand

In interesting idea for saving energy and improving the efficiency of the electricity supply system is 'dynamic demand'. Some devices, like refrigerators, need energy but not necessarily at any time. They can be designed to detect when the electricity grid is most highly loaded (by changes in the frequency of the AC cycle) and avoid drawing current at those times.

A fascinating possibility that is opening up is to use 'Plug-in Hybrid Electric Vehicles' (PHEVs) for this purpose and also to meet peaks in demand on the electricity supply system.

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