Geothermal energy and ground source heat pump solutions are being used to generate electricity to power and heat homes. These renewable energy technologies provide low carbon solutions for sustainable development.
Geothermal energy has been exploited for many years around the globe: in1904 geothermal energy was first used as a source of power. On the 4th July 1904 in Larderello, Italy, a business man, prince and Italian politician Piero Ginori Conti, tested the first ever geothermal power generator. The small generator provided enough power to illuminate a few light bulbs. This was the beginning of the modern geothermal industry according to the Clean Energy Ideas web site. Piero continued to develop the technology and went on to build the pioneering geothermal power plant. It became operational in 1911 at the Valle del Diavolo or Devils Valley, also in Larderello. This ‘dry-steam’ geothermal power plant would provide electricity for the Italian railway system and would remain the world’s only geothermal power plant for a further 11 years until 1922. The regional geology of the area makes it conducive to geothermal power production, as there are hot granite rocks that are close to the surface producing steam as hot as 202°C.
Today there is a geothermal museum, the Museo Geothermica, in the town to celebrate the past developments. The geothermal power plant here today generates around 10% of the world’s entire supply of geothermal electricity: 4,800 GWh per year which powers around a million households. From the Italian beginnings, geothermal power is now being used around the world. New Zealand was the next country to develop a major power plant using this source of power in the 1950s. That country has plenty of geothermal potential for power.
Geothermal energy companies now drill wells and harness rising hot water from the well in order to extract heat to generate electricity or to heat nearby homes. Today there are around 600 geothermal power plants globally according to this BBC report. Typically those plants are in active seismic zones where there are tectonic plate boundaries. It is likely that the number of power plants will double and there are many being planned in Europe, Africa and other continents.
Even countries that are not located close to tectonic plate boundaries may have sources of geothermal power. Power generated from these sources utilise much lower water temperatures than those on active tectonic boundaries. In the UK the first geothermal power (binary) plant is situated in Cornwall, south west England, an area associated with granite geology. The company has drilled the deepest well in the UK at over 3 miles (5275 metres) deep in a geological fault: the Porthtowan Fault. The temperature at that depth is around 200°C. This power plant has been developed with a mix of public and private money and will generate power over many years in the future. The initial plant will produce 3MW of geothermal electricity sold through green energy supplier Ecotricity who specialise in selling only renewable sources of energy. This project follows on from the UK’s first lido supplied by geothermal hot waters, in Jubilee Pool, Penzance, also in Cornwall.
This geothermal power supply will be expanded to produce up to 20MW of electricity. The initial supply, from the 3MW plant, will be enough to provide power for 10,000 households. The benefit of geothermal power is that it will offer continuous power that is of a consistent output through the day and night.
The New Power Source To Heat A Historic English Village
In 2017 Swaffham Prior Community Land Trust and Cambridgeshire County Council initiated a project to bring renewable energy to Swaffham Prior, a village in the east of England near Cambridge. Following a series of technical studies, it was decided that a Ground Source Heat Pump would provide thermal energy to be pumped through a network and into village households. There is also an electrode boiler as a backup supply.
The £9 million project will extract underground heat. The village has no mains gas and one resident spends £3,750 each year, on average, to buy fuel oil. The heat network should save £500 each year. 150 homes aim to connect to the UK’s first village zero carbon heating system. Heating Swafham Prior will provide a network of hot water linked to the ground and air source heat pumps. The scheme encourages residents to sign up with no up front costs and they should save around £500 each year based upon current heating costs. Construction is due to start in the spring and the project will begin to deliver new heat in May 2021.
260 boreholes, up to 200 metres deep, will allow water will be circulated underground by pumps with heat exchangers to raise the temperature to 75°C. Each home will have a small heat interface to use the water for heat and hot water. An air source heat pump will supplement the ground source heat pump and a 750W solar array will provide about half the power to run the system. More than 160 out of 300 homes have expressed an interest. This number may increase as the benefits become obvious. Collective community change is important for this project. The £9M project is largely funded through public funds as an evaluation project for the technologies.
Properties with existing radiators do not need to upgrade them to join the heat network. The system has been designed to supply heat to all 300 homes in the village of Swaffham Prior, including the historic (listed) buildings. A heat interface unit will be installed in houses which will receive heat from the central energy centre. Current boilers will be replaced with the heat interface which operates at the same temperature range, of 70 – 75°C, as boilers. This means it can integrate with an existing central heating systems aiming to make the changes hassle free; without making additional changes within the households.
These two schemes highlight long term zero carbon solutions to electric power and heat provision. Both are avoiding pollution and the technologies offer the beginnings of sustainable, localised heat and electrical power provision projects. Model schemes, such as these, could be adopted by other villages or community power projects. They both work well with other renewable power mixes, if needed. The Swaffham Prior village example enables the removal of expensive fossil fuel based heating oil heating systems. Whilst both solutions have a high up-front cost, the overall longer term cost of energy is cheap and reliable.