Geothermal energy provides heat and electricity
Interest in (deep) geothermal energy is growing rapidly. Geothermal energy is a renewable resource that can provide both heat and base-load electricity. Geothermal energy is derived from heat below the Earth’s surface. It is harnessed either by utilizing existing aquifers or by injecting water below the Earth’s surface and then recovering heat from it. The heat originates from various processes that take place within the Earth’s core, at a depth of 5,000 to 6,500 km where the temperature is estimated to be over 5,000ºC. The heat is transferred to the surface and, due to the properties of the Earth, temperature increases with depth. Temperature increases vary from one point on the Earth’s surface to another. To use geothermal energy for electricity production, a geothermal steam turbine is needed. This is, so to speak, a thermal turbine in which Mother Nature stokes the boiler.
Harnessing geothermal power is a global activity and, therefore, an ideal fit for a global market player like DNV KEMA. Africa - particularly in the Great Rift Valley - has great geothermal potential. A Dutch consortium, headed by DNV KEMA and IF Technology (IFT), has investigated the potential of geothermal energy in Tendaho Field, Ethiopia. The consortium has also identified major obstacles to harnessing these resources, including grid-connection issues, lack of power-plant facilities, underground reservoir capacities, and so on. Other sustainable-energy projects with a focus on geothermal power are underway in countries such as Sudan and Indonesia. Considerable geothermal potential exists also in the U.S. and Europe. Studies have been carried out in Germany and elsewhere to increase scientific understanding of heatto- electricity conversion technologies and heating systems. In the Netherlands, researchers have looked into the possibility of using geothermal systems to heat homes and greenhouses, and/or creating underground heat-cold storage systems. DNV KEMA’s focus is mainly on highefficiency heating, cooling, and power generation (above-ground infrastructure).
DNV KEMA undertakes studies for government bodies and supports the success of our clients’ geothermal projects by providing engineering services, such as
Feasibility and conceptual studies
Heat and power-plant planning, e.g., using oganic rankine cycle ORC process utilization
Facilitating licensing and permit procedures
Power-grid and heat-grid integration
Technical and economic optimization
Cooling water cycle and cooling tower consultancy
Water treatment (softening) and well system integration
The main reason for using geothermal energy is that it is renewable. Moreover, the CO2 emissions associated with geothermal energy are negligible. The supply of energy from a geothermal resource is fully controllable. Geothermal energy can be used to run existing heat-distribution systems, or for electricity production if the temperature is 150°C or higher.
DNV KEMA, the Netherlands
IF Technology (IFT), the Netherlands