Heating up

In the quest to replace our dependence upon fossil fuels, the UK has sought to explore the various options available to us for sourcing power for the future. While nuclear power has been seen as the quickest and easiest option to exploit, the arguments regarding its long term impact and safety has allowed renewable energy sources to gain a new presence on the national agenda.

With our long coastline and temperate weather conditions, tidal and wind power have always seemed the most logical and popular scheme for generating power. However another option in geothermal energy has been on the whole an unfortunately neglected consideration. Though currently providing power for around 60m people around the world, as an energy option for the UK the idea of using the Earth’s heat as a source of power has been largely ignored as fantasy.

However, geothermal energy is now set to become reality. In August 2010, planning permission was granted for Geothermal Engineering Ltd to build the UK’s first commercial geothermal power station near Redruth in Cornwall. The area was chosen due to its geological structure which offers some of the best depth to temperature ratios for depth drilling. Following test holes to establish suitability of the geology, a well will be drilled 4.5km down into the ground. A plant will then be established on the site that will pump fluid into the hole. The heat of the rock below will raise the temperature of the fluid to over 100 degrees Celsius where it will then be used to power turbines that can generate electricity as well as facilitate hot water for nearby residential, industrial and agricultural purposes.

With construction due to begin in March 2011, it is estimated that in full flow the operation will contribute almost 10 megawatts of electricity to the national grid (the equivalent of 21 wind turbines) and 55 megawatts of heat to the local community, saving a significant amount of fossil fuels usually used in heating homes. In addition, where other renewable energy sources are limited by wind strength or tide, the geothermal plant has no such constraints and as will be able to operate around the clock.

So impressive are the possibilities offered by geothermal power that the project has already been awarded almost £1.5m in funding by the Department of Energy and Climate Change. Future projects are already being explored, including the possibility of another plant to be situated near to the Eden Project in Cornwall. And it has been predicted by some parties that the UK could eventually generate between one and four gigawatts of power. This represents as much as a tenth of the UK’s total requirement.

Deep impact
Understandably, there has been some concern regarding the project. To begin with there is the issue of drilling the well required to access the hot material. A 50m high drill will be used to achieve this, which will visible for many miles around the area and require 60 articulated lorries to move it into position, significantly increasing traffic in the area. This will produce noise of the value of around 50 to 60 decibels in the local area, the equivalent noise of a car engine when driven at 70mph. This will continue for a period of five months per well.

Perhaps more concerning though is the implications of pumping fluid into the well.

While the geology of the area has been carefully studied to assess potential impact, geothermal energy is not an exact science. As such the cool fluid touching hot rock could potentially lead to micro earthquakes occurring in the area, though nearly all will be unnoticeable on the surface. Many of the countries that currently make use of geothermal power do so in areas of geological instability, such as along the earthquake prone coast of California in the US or the volcanic North Island of New Zealand, and find the potential of micro earthquakes of little worry. Residents of Redruth however may have concern with what is going on underfoot, with a possible impact on value of property in the area.

However, the impact of geothermal is far less than other suggested renewable energy sources, creating neither the controversy of wind farms nor the ecological change required to establish tidal power.

The future
Realistically, the UK won’t be able to embrace geothermal technology to the levels of countries such as Iceland, where it services nearly 90 percent of home heating. Simply, the geography of the UK isn’t compatible to achieving this. However, as pointed out by James Woudhuysen, Professor of Forecasting and Innovation at DeMontford University in his energy white paper Energy: it’s the heat, stupid!, applications around the UK are plentiful. The flooded mine shafts of the Scottish Highlands, Woudhuysen asserts, could potentially be used to generate 300 megawatts of heat. If replicated at other sites this could begin to detract from the need for fossil fuels.

There is however a long way to go on the technology. Research into its application is probably ten years behind that of wind and solar, meaning much funding and development will still be required. As such, projects are currently hugely expensive with the Redruth geothermal plant costing around £40m to build, a considerable outlay in terms of energy produced. Yet as a pioneer of the technology in the UK, the money can be considered well spent if it leads to a lower carbon future.

The UK’s energy future does not – and indeed should not – belong to one particular type of technology. In terms of both our carbon future as well as our political future, as exemplified by the Belarus-Russia gas dispute, our dependence on fossil fuels has to reduce significantly over the next 20 years. Geothermal, nor any other renewable energy, is likely to get us all the way there. But the more cards you have to play, the better the hand you have.