Learning from the Romans

Diagram of Geothermal Engineering

Geothermal energy has been exploited since the years as the discovery of naturally occurring hot springs and aquifers was made in the Roman times.

Over the years the technology used to harness geothermal energy has developed and systems of up to 5km can now be engineered (RA, 2013). In such systems water is injected into the earths hot rock and extracted after it has been heated (see image). Although there are high levels of risk involved in the initial exploration and high capital requirements, geothermal energy systems are expected to provide energy for up to 50 years and as a result they provide what would seem to be a very reliable and cost effective source of on demand power, heat and cooling.

A major benefit of geothermal energy is that the estimated 99.9% of the earths mass estimated to have temperatures of over 100 degrees are continually maintained due to the presence of radio active decay in the Earths surface (RA, 2013).

In addition to this another key benefit is the fact that geothermal energy does not release any CO2 into the atmosphere nor does it produce any flue gas emissions such as soot particles and sulfur dioxide (Stober and Bucher, 2013)

The cost of drilling and engineering geothermal wells is estimated to be around US$1.5 to 3 million with a cost per drilled meter of US$800-1200/m and commerical and well depth is generally set at a maximum of 3km (Kingston Morrisson, 1996). The costs of drilling involve a degree of uncertainty if lost circulation zones are encountered and fluids are lost in rock fractures then the costs will increase (Barbier, 2002). Although these estimations are likely to have changed to some extent since they were made in 1996, the costs are nevertheless relatively low and and as a result geothermal energy presents itself as a cost effective method.


Worldwide

Image of a geo-engineering plant

Lund and Freeston (2001) estimate that in 2000, the global production of geothermal power was 15,145 MWt, utilising at least 52,746 kg/s of fluid and the thermal energy used is 190,699 TJ/yr. This thermal energy was used is a number of sectors such as swimming pool heating, space heating, geothermal heat pumps, greenhouse heating and industrial applications. For this, 1028 wells were drilled, 3362 people were employed to work on them and the total investment over 5 years on geothermal energy was 841 million US dollars.

The United Kingdom
In the UK, geothermal district heating is currently being used in Southhampton and Cornwall. According to DECC, Cornwall alone has the potential to supply 3GW of electricity from deep geothermal sources. The potential of geothermal energy to serve urban areas where there is a combined heat load is high and as a result a number of drilling rigs have been designed specifically for urban areas.  At present the market from geothermal heat in the United Kingdom is undeveloped and there is therefore a lot of potential to expand the drilling, geophysical, manufacturing and support sectors of geothermal energy in the UK.

Developing Countries
Geothermal Energy offers a viable energy method for developing countries as in addition to providing energy, it will also provide jobs (Ogola, 2012). Its low carbon footprint will ultimately serve to mitigate the impacts of future climate change which is particularly significant for developing countries in Africa as climate change's effects will be worse in these regions.