From Greenhouse to Green House

 

RENEWABLES, THE HAIR SHIRT AND NUCLEAR POWER

Gerry Wolff

In 'green' thinking there is an issue that needs careful attention but is often not clearly articulated: should we solve environmental problems by reducing our demands for warm houses, nice food, fast and comfortable travel etc, or should we solve environmental problems by developing new technologies?

Amongst some environmental campaigners, the first view seems to be linked to a quasi-religious idea that wearing a hair shirt is a moral good in its own right. Whatever the intrinsic merits of that outlook, it will be difficult or impossible to persuade the majority of people to share it. They are most likely to reduce their demands if they see that is in their own interests or those of their descendants.

My own view is that demands on the environment do need to be reduced (the world is finite so there is clearly a limit on what we can demand from it) but that new technologies can go a long way towards satisfying our needs and more frivolous desires in a sustainable way.

With regard to CO2 emissions and the need to reduce them, there is an idea - promoted most notably by James Lovelock - that renewable technologies cannot meet our needs and that, despite its clear disadvantages, nuclear power is a necessary stop-gap. Unfortunately, Marcel Theroux, in his otherwise excellent TV programme about global warming (Channel 4, 8 January 2005), has adopted and promoted this idea without any serious examination of the alternatives.

I believe we can make the deep cuts in CO2 emissions that are necessary without using nuclear power and that there is far more potential in renewable technologies than is generally recognised. In any case, nuclear power is merely a method for generating electricity and electricity is not by any means the beginning and end of our energy needs.

The following sections summarise the possibilities as I see them. The first is about capturing or generating energy, the second is about transforming and transmitting energy, and the last is about saving energy.

Energy capture and generation

Wind power

Wind turbines are a well-developed technology and the potential is huge. The UK has been estimated to have over 33% of the total European potential offshore wind resource - enough to power the country nearly three times over (BWEA - offshore wind). There is similar potential in many other parts of the world.

A common objection to wind power is that the wind does not blow all the time. But a conventional power station only generates electricity for about 50% of the time. And the demand for electricity varies from minute to minute. We need a mix of different systems to provide the electricity we need.

Although the wind does not blow all the time, wind power could provide us with 100% of the electricity we use. How is this possible? When there is more wind power than we need, the surplus electricity is used to generate hydrogen which is stored. When the wind drops, the stored hydrogen is used as fuel for an engine that drives an electricity generator. This technology has been developed by Anglesey Wind and Energy. (More in 'Energy transformation and transportation', below)

Tidal stream

It has been estimated that 20% of the UK's electricity demand could be generated from tidal currents in the sea using underwater turbines, similar to wind turbines but designed for the high energies of tidal currents and other conditions in the sea.

Links:

  • Ocean energy.
  • Orkney Renewable Energy Forum.

Wave power

The disastrous effect of the recent Asian tsunami has demonstrated in a tragic way the enormous amount of energy that can be carried by waves. From at least as far back as Stephen Salter's 'ducks', prototype systems have been developed for capturing the energy of waves. One of the most promising at present is the Pelamis 'sea snake' comprising a jointed tubular structure designed to float on the sea, flex with the waves and capture the wave energy by means of hydraulic rams, turbines and generators. Each single 750-kilowatt Pelamis could generate the same amount of power as a wind turbine and a 'wave farm' covering a square kilometre of ocean would provide enough electricity for 20,000 homes.

Concentrating solar power

In sunny parts of the world, the sun provides huge amounts of energy and large amounts can be captured very effectively by 'concentrating' solar devices. For example, 'power tower' systems use a large field of sun-tracking mirrors to concentrate sunlight onto a receiver on the top of a tower. The sun heats a fluid inside the receiver. An early demonstration plant used water as the fluid, generating steam in the tower to drive a turbine to generate electricity.

There are many variations on this kind of idea. In one, molten salt replaces water as the vehicle that is heated by the sun's rays. The salt's heat is used to generate electricity through a conventional steam generator. Molten salt retains heat efficiently, so it can be stored for days before being converted into electricity. That means electricity can be produced on cloudy days or even several hours after sunset, thus to a large extent overcoming the problem that the sun does not shine at night.

'Farms' of concentrating solar power generators may be constructed in any of the world's hot deserts. Although distances may be too great to allow the direct conduction of the electrical power to centres of population, the electrical energy may be used to create hydrogen and this may be piped where it is needed or transported using tankers (see 'Energy transformation and transportation', below)

Photovoltaics

Although PV panels have been expensive, there are improvements in the technology and costs are falling (see SunPower,  H-Alpha Solar and Flexcell). We may be approaching the point where it is feasible and affordable to install PV panels on any surface that receives sunlight.

Small-scale generation

There is a growing realisation that much of the electricity we use could be generated domestically by small-scale wind turbines, combined heat and power, heat pumps and photovoltaics. Some of the possibilities are described here:

  • By the Green Alliance.
  • The US National Academy of Engineering.

Energy transformation and transportation

Electricity is not ideal for every application and there are limits to the distances it can be transmitted without unacceptable losses.

The simplest conversion is to pass electricity through water and capture the hydrogen that is generated. This may be stored and used to generate electricity at a later time (as above) or it may be transported by pipe or tanker to where it is needed as suggested for concentrating solar electricity generated in deserts. It may also be used as input to a fuel cell or an ordinary internal combustion engine that has been tuned for that fuel.

An article in the New Scientist describes how powdered iron, aluminium or boron may serve as a very effective energy vector.

Energy saving

Insulation

In cold climates, a lot of CO2 is emitted by burning coal, oil or gas to keep us warm. Much of this can be eliminated by using levels of insulation that are much higher than have been traditional in the UK but are not unusual in countries like Sweden or Canada (see also Domestic Heating).

The Internet

In principle, a lot of business travel can be eliminated by the use of video conferencing via the internet. No doubt the internet will have to improve before this kind of communication can be as good as face-to-face meetings but even now there is clear potential for reducing CO2 emissions from business travel, especially if there are incentives via carbon taxes and carbon rationing.

Conclusion

The potential of renewable forms of energy generation, coupled with energy saving, is huge. There is no need to return to nuclear power with all its problems.

Last updated: 24 October, 2005.