Geo-pressure
Geo-pressure will generate electricity wherever a pressure reduction station (PRS) is used to lower gas pressure. There are currently more than 2000 suitable locations in the UK for this technology and harnessing the energy from geo-pressure could provide the UK around 1GW of extra productive capacity, equivalent to that of an average sized fossil fuel or nuclear power station. It has the potential to save the UK a minimum of one million tonnes of carbon emissions (1MtC). As well as being completely carbon free, geo-pressure generation would, if properly exploited and supported, be an excellent potential source of decentralised or, as its sometimes called, distributed energy.

But what is decentralised energy and why should it be an important part of the UK’s strategy for tackling climate change? We answer this first by explaining the problems with our current system for generating and distributing electricity.

Centralised electricity generation and distribution
Do you know that almost two-thirds of primary energy is wasted in the UK’s centralised electricity system? In other words, for every 100 units of energy contained in the fossil fuels used to generate electricity, only 38.5 units are put into the national grid for distribution, with 35 units being eventually supplied to the customer. They waste a further 13 units through inefficient use, leaving just 22 units for utilisation. Source: Decentralising Power: An energy revolution for the 21st century – Greenpeace (2005)

Devised in the 1930s, around inefficient coal pits, the waste inherent in this system now accounts for 20% of the UK’s annual carbon emission total.

Furthermore, this gloomy picture is mirrored throughout the developed world.

What is decentralised energy and why is it important?
Decentralised or distributed, energy is where energy in the form of either heat or electricity is generated close to or at its point of use. All types of buildings - ranging from terraced houses to the largest factories – cease to be just passive consumers of energy, as they currently are, and instead become power stations themselves, the constituent parts of local energy networks.

There are many different technologies that can be used to generate energy in this way including photovoltaic, solar, wind turbines and cogeneration (combined heat and power) units. If the energy released from reducing gas pressure is included as a source, then geo-pressure can be added to the list.

Geo-pressure fits particularly well into a decentralised energy model because it can be used to generate power during peak periods – daily peaks, as well as seasonal peaks. More power is generated when more gas travels through the system - for a given supply pressure - so as gas demand peaks, geo-pressure generation increases. Gas demand is closely linked to electricity demand, so geo-pressure generates electricity at the most useful time, reducing the need for surplus capacity on the local grid.

Geo-pressure requires no extra land-take, and has very limited visual impact. Nor are there significant implications for the planning system, as turbines are fitted within existing pressure reduction stations. Geo-pressure turbines are small – a turbine with a 1MW capacity is only 20cm across.

Decentralised energy is important because electricity production currently accounts for one third of the UK’s carbon emissions. Greenpeace and others estimate that investing in a decentralised energy strategy would enable the UK to reduce “at least half of all emissions from the UK electricity sector, or 15% of total UK emissions”.

Conclusion
With more than 2000 locations in the UK able to use geo-pressure profitably today to generate electricity, geo-pressure is eminently well qualified for inclusion in any decentralised or distributed energy production strategy. In fact, these 2000 plus locations could already be viewed as a potential series of linked local distribution networks for renewable electricity.