Turning the tide for alternative energy

GOVERNMENT MINISTERS in Britain are supporting a controversial £14 billion scheme for harnessing the power of the tide. Tidal power now seems to play a more significant part in plans for energy production. In the latest in our series on renewable energy sources, Tom Baldwin asks: Has the tide turned for tidal power?

IN ORDER to meet even the modest targets set by the European Union (EU) the UK needs to produce around 35% of electricity generation from renewable sources by 2020. The figure currently stands at just 4%!

Tidal power is a clean alternative to burning fossil fuels; it produces no greenhouse gases or pollution. It is also a much more reliable source of power than other renewable technologies such as wind or solar power as tides rise and fall in regular patterns. Efficiency also compares favourably.

The tides' movement is caused by the effects of gravity from the sun and the moon. Especially in an island like Britain the potential for harnessing this power is great.

There are two main ways of generating electricity from the tides, with a tidal stream generator or with a barrage. The tidal stream method is simpler, relying on tides to turn an underwater turbine. These work on the same principle as a windmill but using the movement of the water, instead of the wind to turn it.

A prototype of such a generator is in place off the North Devon coast, near Lynmouth. Currently this has blades 11 metres long and is capable of producing 0.3MW (per second). This is significantly less than an average turbine on a wind farm (capable of producing around 2MW) but there are plans to upgrade and expand the site.

Environmental impact

Being underwater there are also far fewer issues with visual impact than wind turbines and energy production is much more consistent. Environmental impact is also low; the blades turn slowly and so do minimal damage to fish populations.

Building a barrage to generate electricity from the tide is far more complicated and costly. This involves blocking a whole estuary and using the difference in height between high and low tide to generate power. A reservoir or barrier usually traps water in at high tide; this is then allowed to flow out at low tide, turning a turbine as it goes.

Currently the biggest such generator is on the Rance in Brittany, France. This has a 240MW capacity and has been working for over 30 years. However the river Severn in the UK boasts a tide height of 45 feet, the second highest in the world and so has incredible potential for tidal power.

Barrage or lagoon

A RECENT government white paper proposes realising this potential by building a barrage ten miles long between England and Wales at a projected cost of around £14 billion. This huge project could produce 5% of the country's electricity when it is at full capacity.

The proposal is not without controversy as any construction project on this scale would have a huge environmental impact, let alone one that blocks an entire river estuary. The Severn estuary is an important area for many species of fish and bird and the barrage could have a negative impact.

Unlike the tidal stream turbines a barrage can kill high numbers of fish trying to cross it; it can also disturb nesting sites and through the depositing of silt, alter the whole estuary.

Environmentalists are proposing a series of smaller 'lagoons' be created, each capable of producing electricity but without blocking the whole estuary. They claim this alternative would be less harmful to the area and even produce more electricity.

While tidal power is a vital technology for green energy production, like other renewable energy sources it is not the answer to all our problems. Clearly, something radical must be done to avert climate change. However, the enormous costs of building barrage systems mean they are hard to get off the ground as companies baulk at the high capital costs and slow return of profits.

Under capitalism the need for short-term profits remains the most important motive of any company, squeezing out necessary, longer-term projects. The fact that New Labour are thinking on this scale reflects that capitalist governments are beginning to wake up to the dangers of climate change.

However even the £14 billion proposed for this pales when compared to the £76 billion the government is prepared to spend on replacing Trident nuclear weapons.

To meet the EU targets, by 2020 the UK will have to be producing 20% of our electricity from wind and around 10% from tidal and hydroelectric sources. This will prove a huge challenge and yet even these targets are insufficient.

Theese targets were set up within a framework of capitalism and reflect big business' need to keep profits up. Ultimately this system, based on the blind forces of the market, can never solve the crisis facing our environment.

Socialist planning

Only a socialist plan of the economy could allocate resources based on need, not on profitability. Money could be properly invested in research for new, clean energy sources or for improving existing technology. Money could also be made available for big projects while carefully weighing up the environment's needs and local people's concerns, not simply the desires of big business.

Planning would mean matching supply to demand and removing unnecessary haulage. Increasing energy efficiency and eliminating capitalist overproduction would vastly decrease the amount of energy consumed.

A democratic, socialist plan of production would also eliminate much of the waste and duplication that exists under capitalism. Competing companies replicate similar goods and products are moved around the world to increase profitability.

A socialist energy policy would see a huge increase in the use of technology such as tidal, wind and solar power to replace the burning of fossil fuels. The potential for such technology would not be allowed to go to waste.

Tidal power is an important weapon in the armoury against climate change but under capitalism this will not be enough. There will not be enough investment and big business will resist change. Only the replacement of that system with socialism can avert the oncoming environmental crisis.

The future of our planet must be given priority over the profits of a handful of billionaires.

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In The Socialist 21 June 2007:

New PM... same old Bosses' agenda