Alexandra Latham
Alexandra Latham is in charge of communication at the European Geothermal Energy Council, working to facilitate growth in the sector by increasing awareness and improving access to information.
A quick glance at the stark figures for heating and cooling in Europe is enough to make clear the need and the potential to improve our energy system by tackling this sector. Heating and cooling represents half of the final energy consumption in Europe whilst 70% of the thermal energy used in buildings comes from burning natural gas, meaning expensive imports, vulnerability to price changes, and the environmental and social dangers inherent in fossil fuel use. In 2013, just 16.5% of the EU’S thermal energy demand was covered by renewables- although this represented 51.5% of the total renewable energy consumed.
Whilst the amount of thermal energy supplied by renewables is small compared to fossil fuels, the potential is much greater. It is feasible that by 2020, 25% of thermal demand could be covered by renewables. That would mean that the number of jobs, already 470,000 in 2013, would more than double, and EUR 21.6 billion would be saved annually in imports compared to 20121.
Geothermal energy can provide heating and cooling in many different ways. Shallow geothermal energy harnesses the constant underground temperatures from about one metre underground onwards, with efficient heat pumps used to adjust the temperature to that required in the building. Underground Thermal Energy Storage (UTES) means that thermal energy, at temperatures ranging from 90°C to 5°C, can be stored underground until it is needed. Both shallow and deep resources can be used in district heating networks which can be small, in the range of 0.5MWth- 2MWth or large, with capacities of around 50MWth. Deep resources which are used to produce electricity often also produce heat, in Combined Heat and Power (CHP) plants.
©iStock/Francesco Scatena
Shallow geothermal all over Europe.
Shallow geothermal energy is by far the most exploited in Europe, with more than 1.4 million heat pumps installed, providing more than 19,000MWth in 2014. It has, however, been difficult to effectively evaluate the number of installations and energy produced as reporting has not been uniform. This has recently been clarified by the Commission (decision 2013/114/EU) and new data is expected soon.
Most of the installed geothermal heat pump systems (also known as Ground Source Heat pumps, GSHP) are in Sweden, Germany, France, Switzerland, and Norway. However in Central and Eastern Europe an interesting pattern is emerging: although sales numbers are low in absolute terms, the rate of growth is exponential and the market is increasing much more rapidly than in the rest of Europe.
The industry received a boost in September 2015 when new energy labelling and eco-design rules came into force in Europe. These rules concern nearly all boilers, combi boilers and water heaters with rated heat output of less than 400 kW as well as for hot water storage tanks with a storage volume of less than 2,000 litres, labelling them according to efficiency. Geothermal heat pumps are amongst the few to be placed in the highest category, A++ until 2019, after which A+++. GSHP fall into this category as the Seasonal Performance Factor (SPF), the ratio of the heat delivered to the total electrical energy supplied over the year, is today above 4 (benchmark standard), and is heading towards 5 in the near future2.
Shallow geothermal energy is being used in one of Europe’s largest passive tertiary buildings which opened in Brussels in 2015. The Brussels Environment building has 16,700M2 of floor space with thermal energy provided by two 80m boreholes connected to thermo-active floor slabs. It is an exemplary building, demonstrating the use of geothermal in synergy with other renewables like solar as well as energy efficiency measures. The smart grid concept can also be applied to shallow geothermal as it is in the Ümraniye Meydan Shopping centre, Istanbul. One of the largest shallow systems in Europe, 208 Bore Hole Heat Exchangers (BHE) were installed at an average depth of 88m and connected to a hot water loop, using individual heat pumps to direct the thermal energy to where it is needed and providing seasonal thermal storage. In total, the project saves the emission of 350 tonnes of CO2 per year.
Geothermal district heating (GeoDH) is an ongoing European success story.
The rate at which new GeoDH capacity is installed has been increasing every year for the last five years; an additional 93.3MWth was installed 2012 and 50 MWth in 2015. Growth is happening in three directions: countries with a history of geothermal district heating systems, such as France and Hungary, are continuing to develop their resources in new ways; the Central and Eastern European market, which has a good but under exploited resource, is beginning to develop - Serbia will have the 6th highest number of systems by 2019; and new markets such as the Netherlands are building on lessons learnt elsewhere to develop new and innovative systems. New systems are being built, and existing, fossil fuel systems are being retrofitted to run on geothermal energy.
At the end of 2015, there were in Europe 257 district heating plants operating with geothermal energy, with a total installed capacity of 4701.7MWth. Of these plants, 177 with a total capacity of 1551.8 MWth were in the EU. The countries with the highest capacity are diverse, with Iceland leading the way followed by Turkey, France, Hungary, and Germany. The sector is growing, but remains a fraction of what it could be: there are 5,000 district heating systems in Europe and 25% of the EU population lives in areas directly suitable for Geothermal District Heating.
The development of smart thermal grids, where geothermal is integrated into a flexible, intelligent grid system, is key to future GeoDH development. In smart grids, geothermal resources can be used for base load district heating and (through absorption chillers) district cooling, whilst CHP plants can adapt the share of heat or power produced depending on demand. Shallow geothermal can also be used, with thermal energy storage (UTES) stabilising the grid, and heat pumps providing thermal energy and storage at an individual level.
An excellent example of innovative behaviour in new markets can be found in Heerlen, a former coal mining town in the Netherlands. After their closure, the local mines flooded with groundwater, creating a geothermal resource. In 2005 the town began to investigate using this thermal energy for heating and cooling with a project supported by the European Interreg IIIB programme and the 6th Framework Programme. The concept was proved and now Mijnwater B.V. is an expanding municipally-owned private company which is continuing to diversify and develop.
In its first stage, from 2008-2013, the low temperature resource was delivered to clusters of buildings in a grid, with heat pumps used to adjust the temperature, resulting in a CO2 emission reduction of 35%. In the second stage, the mine water was used and a reservoir as well as a source, making sure that the resource is not depleted. The grid was expanded and users continued to be grouped into clusters, with energy exchanges both within and between clusters and surplus energy transferred back to the reservoir for storage. Whilst most thermal grids have a top-down structure with a heat plant at the top, the Mijnwater network is based on equal connections in a decentralised system. By 2014, CO2 emissions had been reduced by 65%. The project, now in its third stage, is changing into a responsive system where supply is altered based on a number of demand-side factors, including the weather and customer demand, and which works in synergy with other renewables.
The future for geothermal heating and cooling
The potential for geothermal is clear but in the next few years some developments must be made. This includes increasing the rate of installation retrofits and refurbishments by making systems easier to install, developing technology which can be used in low-temperature district heating systems, improving the market conditions to make renewables competitive compared to classical alternatives like fossil fuels, and expanding the roll out of Enhanced Geothermal Systems (EGS), a European breakthrough technology which is creating potential for deep geothermal where none existed before.
1Common Implementation Roadmap for Renewable Heating and Cooling Technologies, RHC-ETP
2See RHC-ETP Strategic Research Priorities for Geothermal Technology and Geothermal Technology Roadmap