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Q. How will energy demand and generation develop in the future?
A. The annual worldwide energy demand is increasing dramatically and we know the contributing factors: population growth and the related demand for housing and consumption, economical development of the newly industrialized countries, as well as the globally growing logistics sector. We are all aware that energy generation from fossil fuels will come to an end and that related greenhouse gas emissions are a decisive factor for climate change. What we need is a shift in thinking—to look the energy cycle holistically, and therefore, energy generation from renewable sources.
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Q. Deep geothermal energy is your speciality. What are its benefits?
A. Temperature increases with each meter into the Earth’s core–with each kilometre equalling about 30 °C. In general, one can assume that the temperature at a depth of 3,000 m is approximately 100 °C—the temperature at which water vaporizes. Geothermal energy at this depth can be used by power plants with water-vapour geared turbines to generate energy. This form of thermal energy is available at all times, not dependent on seasons, and is more or less inexhaustible. While the installation of geothermal power plants is possible everywhere, areas with higher temperature gradients, like Iceland, Tuscany in Italy, or the German Upper Rhine Rift Valley, are best suited for this technology. In those places, temperatures of several hundred degrees can be achieved at lesser depths.
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Q. What are future considerations for geothermal energy?
A. Geothermal energy’s inexhaustibility and availability is a great advantage in comparison with other energy sources. Currently, there are two fundamental methods for deep geothermal energy generation, and they differ in the occurrence of the required heat exchanger medium (e.g., groundwater). If the medium is available, the process is called hydrogeothermal energy. If the heat medium must be supplied artificially, the method is called the hot-dry-rock process, or HDR.
Deep geothermal energy is being continuously investigated and so far, not nearly all opportunities for the generation of heat and its efficient conversion have been found. My personal project experience with both methods shows that the application of the hydrogeothermal method can already be cost-effective. The HDR process still needs more research to advance the technology further.
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Q. What changes do you see in the public and private sector regarding energy?
A. Many cities and municipalities have developed programs to reduce carbon dioxide (CO2). Those programs focus on renewable energies to substitute fossil fuels, and many governments fund, support, and advance the use of renewable energies. The private sector is also rethinking energy. Production processes are being environmentally optimized, and more and more waste and by-products are being used to generate energy. By relying on renewable energies, companies are becoming less dependent on oil and gas, and reducing their CO2 emission.
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Q. How would you characterize yourself?
A. I believe I have a balanced and calm personality. My inner balance and quiet, but objective approach, combined with an ounce of curiosity have always advanced my projects as well as my personal life positively.
Dr. Heiner Menzel, department head and specialist for deep geothermal energy in Germany, holds a doctorate in nautical engineering and has more than 20 years of experience in the energy industry. For several years, Dr. Menzel had the leading position of the German deep geothermal energy project in Landau, Germany.
