Hot rocks and potential energy
YEAR 2018 sees carbon dioxide emissions rising to the highest ever levels recorded despite pleas to all nations to reduce their carbon footprints.
The 20th century saw the rise of an increasing number of nations, creating electricity and heating by exploiting geothermal energy. As new technology is applied to this method of energy production, so costs have been lowered.
In 2016, the US topped the world’s geothermal electricity production at 3,086 megawatts, followed by the Philippines (1,904 megawatts) with Indonesia just behind (1,647 megawatts).
Indonesia has the largest geothermal energy resources in the world and is predicted to overtake the US in eight years’ time. Currently 29 per cent of the Philippines electricity is generated by geothermal energy.
What is geothermal energy?
Literally meaning ‘hot earth’, this energy is derived through the radioactive decay in rocks together with the continual heat-loss from the Earth’s core.
At the Core/Mantle boundary, it is calculated that the temperature reaches a staggering 4,000 degrees Centigrade which is gradually transmitted upwards into the Mantle and, thus, eventually into the Crust or lithosphere. There, rock and water temperatures reach up to 370 degrees Centigrade.
Hot spring waters were well exploited by the Romans as seen in my nearby city of Bath which they called Aquae Sulis. Today, the Roman baths are a tourist attraction.
The Romans also used the hot springs for underfloor heating.
In the Qin Dynasty, 24 centuries ago, the Chinese established a hot water spa on the Lisan Mountain.
Serious interest in exploiting this hot rock heat from geysers led to geothermal developments in the US and in Italy in the early 20th century.
Geysers in Iceland and Tuscany were used to heat greenhouses 92 years ago and in 1943, steam and geyser hot water was first used for heating houses in Iceland’s capital, Reykjavik.
Iceland’s future is energised by geothermal power
Straddling the Mid Atlantic Ridge and located on one of the world’s hotspots, the centre of this island is fractured by a huge rift running roughly north to south. To the west of the rift, this part of the island is moving on the North American plate and to the east, that part of the island is on the Eurasian plate and so Iceland is splitting in two.
Rising magma, from below the Earth’s crust, is slowly pushing the two plates apart as seen in the island’s 200 volcanoes, numerous geysers and thermal mud pools.
In utilising the high and low pressure steam rising from deep boreholes, turbines are activated and, thus, heat is converted into electricity, supplying 25 per cent of the country’s electricity. The rest is supplied by hydropower, generated by glacial meltwater streams and rivers.
Iceland, once famous for its cod fish, is now more famous for its aluminium smelting and even specialises today in its greenhouse culture in the all year round production of tomatoes, cucumbers, peppers, cauliflowers and even bananas. Such is the power of thermal heating!
New geothermal power plants in new locations worldwide
Originally generating plants were located almost exclusively on the edges of tectonic plates where high temperature geothermal resources were near the surface.
Today, new plant technology and improvements in drilling and extraction techniques allow for a wider range of geological environments for tapping. Drilling costs for boreholes are very high but production costs are low and the original production costs can be clawed back within nine years of production by recycling the original water back down the initial borehole to be reheated underground.
The pressure pushes the hot water and steam to the surface in the adjoining extraction borehole. The steam then drives the turbines which generate electricity.
Malaysia’s first geothermal power plant
Geothermal reservoirs have been identified in the Apas Kiri area of Tawau, Sabah, and are being developed by the Tawau Green Energy Company with the object of selling the electricity generated to Sabah Electricity.
From only a drilling depth of 2.5 kilometres, this plant is on line to come into production next year (2019) with a potential initial output 67 megawatts. Based on advanced geothermal energy techniques used in North Island, New Zealand, it is likely Malaysia’s renewable energy, currently at 0.85 per cent of the total electrical energy generated, will rise to nearly six per cent from the output of this plant alone.
The total project’s cost is estimated at RM670 million and, as stated before, payback will occur in nine years’ time. The energy generated will be ‘green energy’ and enough to supply the East coast of Sabah which in 2018 is 70 per cent diesel-based.
UK’s latest geothermal energy project
This year, on 6 Nov 2018, The United Downs Deep Geothermal project, in a former copper mining area of West Cornwall, started drilling two wells; one is for the injection of water to a depth of 2.5 kilometres and the second is for the extraction of the same water but at 190 degrees Centigrade. This, like the Tawau plant, will see a continuous cycle of water.
Operating for 24 hours a day, it will take six months to drill both wells in the metamorphic aureole rocks surrounding a granite batholith. Once this pioneer plant is in full operation, it will supply the national electricity grid.
Other granitic moorlands (exposed batholiths) in Cornwall, possess ‘wind farms’ generating electricity from their rotating sails.
Aesthetically, these very tall constructions are not pleasing to the eye and act as death traps to birds as well as annoying neighbouring villages and hamlets with their whirring sounds.
In other parts of that county, hectares of former farmland with south facing aspects are occupied with solar panels adding electricity to the national grid.
Geothermal energy plants by comparison have very much smaller sites and are not dependent on the vagaries of the weather for when the sun doesn’t shine or when the winds abate no electricity is generated!
Why was Cornwall chosen for this European funded geothermal project?
It is for the simple reason that the heat produced is from the radioactive decay of uranium ores in the granitic rocks.
Cornwall, noted for its resplendent beaches and hot summer weather, is now a ‘hot rock’ place! A geothermal experiment is also taking place with deep drilling alongside the open air swimming pool – the Jubilee Pool — in a nearby town of Penzance. This town’s name comes from the Old Cornish language meaning Holy headland where it is thought that that the first saint came ashore to convert the pagan people.
This swimming pool, one of two lidos in the UK, is naturally flushed twice daily by the tides. With a geothermal plant on hand, it would be possible to keep the pool heated in the winter months for the benefit of the townspeople and, indeed, help extend the tourist season.
I visited that town (my birthplace) in early Oct and witnessed the erection of a test drilling rig. It is perhaps no coincidence that the former major producers of tin in the world, Malaysia and Cornwall, have these new geothermal plants under development.
Sabah, like Cornwall, has its own massive granitic batholith in the Mount Kinabalu National Park and I just wonder if future geothermal energy explorations will take place in theRanauregionandthenearby Poring Hot Springs Nature Reserve, where the Japanese occupation during World War II saw the construction of the ‘hot baths’ as we see them today.
Certainly there are many other areas in SE Asia where ‘clean’ geothermal electricity could be produced to contribute to a state or national grid.