Direct utilization of geothermal energy 2010 worldwide review

This paper presents a review of the worldwide application of geothermal energy for direct utilization, and updates the previous survey carried out in 2005. We also compare data from 1995 and 2000 presented at World Geothermal Congresses in Italy and Japan, respectively (WGC95 and WGC2000). As in previous reports, an effort is made to quantify ground-source (geothermal) heat pump data. The present report is based on country update papers prepared for WGC2010 and other sources of data available to the authors. Final update papers were received from 70 countries of which 66 reported some direct utilization of geothermal energy. Twelve additional countries were added to the list based on other sources of information. Direct utilization of geothermal energy in 78 countries is a significant increase from the 72 reported in 2005, the 58 reported in 2000, and the 28 reported in 1995. An estimate of the installed thermal power for direct utilization at the end of 2009 is used in this paper and equals 48,493 MWt, almost a 72% increase over the 2005 data, growing at a compound rate of 11.4% annually with a capacity factor of 0.28. The thermal energy used is 423,830 TJ/year (117,740 GWh/yr), about a 55% increase over 2005, growing at a compound rate of 9.2% annually. The distribution of thermal energy used by category is approximately 47.2% for ground-source heat pumps, 25.8% for bathing and swimming (including balneology), 14.9% for space heating (of which 85% is for district heating), 5.5% for greenhouses and open ground heating, 2.8% for industrial process heating, 2.7% for aquaculture pond and raceway heating, 0.4% for agricultural drying, 0.5% for snow melting and cooling, and 0.2% for other uses. Energy savings amounted to 250 million barrels (38 million tonnes) of equivalent oil annually, preventing 33 million tonnes of carbon and 107 million tonnes of CO₂ being release to the atmosphere, this includes savings for geothermal heat pumps in the cooling mode (compared to using fuel oil to generate electricity).     

Direct heat utilization of geothermal resources

Direct utilization of geothermal energy consists of various forms for heating and cooling instead of converting the energy for electric power generation. The major areas of direct utilization are (1) swimming, bathing and balneology, (2) space heating and cooling including district heating, (3) agriculture applications, (4) aquaculture applications, (5) industrial processes, and (6) heat pumps. Major direct utilization projects exploiting geothermal energy exist in about 38 countries, and the estimated installed thermal power is almost 9,000 MWt utilizing 37,000 kg/s of fluid. The world-wide thermal energy used is estimated to be at least 108,100 TJ/yr (30,000 GWh/yr) - saving 3.65 million TOE/yr. The majority of this energy use is for space heating (33%), and swimming and bathing (19%). In the USA the installed thermal power is 1874 MWt, and the annual energy use is 13,890 TJ (3,860 GWh). The majority of the use (59 %) is for heat pumps (both ground coupled and water source), with space heating, bathing and swimming, and fish and animal farming each supplying about 10%.     

Direct application of geothermal energy: 2005 Worldwide review

This paper is a review of worldwide direct applications of geothermal energy. It attempts to update the surveys presented at and after the World Geothermal Congresses of 1995, 2000 and 2005. Seventy-two countries report direct utilization of geothermal energy. In May 2005, the direct-use projects had an estimated installed thermal capacity of 28,268 MWt. The thermal energy usage is 273,372 TJ/year (75,943 GWh/year), a 43% increase over 2000; the annual compound growth rate is 7.5%.The distribution of thermal energy used by category is approximately 32% for geothermal heat pumps, 30% for bathing and swimming (including balneology), 20% for space heating (of which 83% is for district heating), 7.5% for greenhouse and open-ground heating, 4% for industrial process heat, 4% for aquaculture pond and raceway heating, <1% for agricultural drying, <1% for snow melting and cooling, and <0.5% for other uses. The equivalent annual savings in fuel oil amounts to 170 million barrels (25.4 million tonnes) and 24 million tonnes in carbon emissions to the atmosphere.     

Geothermal energy potential for power generation in Turkey: A case study in Simav,Kutahya

Geothermal energy and the other renewable energy sources are becoming attractive solutions for clean and sustainable energy needs of Turkey. Geothermal energy is being used for electricity production and it has direct usage in Turkey, which is among the first five countries in the world for the geothermal direct usage applications. Although, Turkey is the second country to have the highest geothermal energy potential in Europe, the electricity production from geothermal energy is quite low. The main purpose of this study is to investigate the status of the geothermal energy for the electricity generation in Turkey. Currently, there is one geothermal power plant with an installed capacity of 20.4 MWe already operating in the Denizli–Kizildere geothermal field and another is under the construction in the Aydin–Germencik field.This study examines the potential and utilization of the existing geothermal energy resources in Kutahya–Simav region. The temperature of the geothermal fluid in the Simav–Eynal field is too high for the district heating system. Therefore, the possibility of electrical energy generation by a binary-cycle has been researched and the preliminary feasibility studies have been conducted in the field. For the environmental reasons, the working fluid used in this binary power plant has been chosen as HCFC-124. It has been concluded that the Kutahya–Simav geothermal power plant has the potential to produce an installed capacity of 2.9 MWe energy, and a minimum of 17,020 MWh/year electrical energy can be produced from this plant. As a conclusion, the pre-feasibility study indicates that the project is economically feasible and applicable.     

World-wide direct uses of geothermal energy 2000

The worldwide application of geothermal energy for direct utilization is reviewed. This paper attempts to update the previous survey carried out in 1995 (Freeston, 1995) and presented at the World Geothermal Congress 1995 in Florence, Italy. For each of these updates since 1975, the recording of data has been similar, but not exactly the same. As in 1995, an effort was made to quantify geothermal heat pump data and the investment in geothermal energy development. Final update papers were received from 60 countries, of which 55 reported some form of geothermal direct utilization. Three additional countries were added to the list based on other sources of information. An estimate of the installed thermal power at the beginning of 2000 (1995 values in brackets) from the current reports is 15,145 MWt [8664 MWt] utilizing at least 52,746 kg/s [37,050 kg/s] of fluid, and the thermal energy used is 190,699 TJ/yr [112,441 TJ/yr]. The distribution of the thermal energy used by category is approximately 42% for bathing and swimming pool heating, 23% for space heating, 12% for geothermal heat pumps, 9% for greenhouse heating, 6% for aquaculture pond and raceway heating, 5% for industrial applications, 2% for other uses, and less than 1% each for agricultural drying, snow melting, and air conditioning. The reported data for number of wells drilled was 1028, the work by professionals over the five-year period was 3363 person-years, and the total investment over the same five years was 841 million US$, indicating minimum values.     

Potential of geothermal energy in the Kingdom of Saudi Arabia

The Kingdom of Saudi Arabia has rich geothermal energy resources. In Saudi Arabia, the studies on geothermal resources exploration were started in 1980. Saudi Arabia is among the most geothermally active countries in the Middle East. The geothermal power plants are not yet installed in Saudi Arabia. Some direct-use low-grade geothermal applications are already installed in the five last years. Some refreshment and swimming pools are already constructed in the Bani Malik-Jizan area. Geothermal energy can be utilized in various forms such as direct use, electricity generation, space heating, heat pumps, greenhouse heating, and industrial usage. The Kingdom of Saudi Arabia government has plans to become completely powered by difference forms of renewable energy such as solid waste, solar, geothermal, and wind.     

国外能源公司地热能利用现状以及对中国石化的启示

地热能作为一种无污染、可再生的清洁能源,具有稳定可靠、成本低廉、清洁环保等优点。国外能源公司在地热能利用方面积累了成功的技术和管理经验．其中以冰岛绿源公司为代表的地热供暖、以雪佛龙为代表的地热发电、以壳牌为代表的干热岩发电处于国际领先地位。这些公司都拥有雄厚的资金实力、良好的国际声誉以及完整的产业链;并且都集中优势资源,重点发展某一项地热业务．而后再逐渐向地热能利用的其他领域扩张;同时还具备完善的科研设备和一流的科研人员,注重科技创新。中国石化正在积极扩大地热能研究和利用工作,旗下新星石油公司已发展成为国内常规地热能开发利用的第一大公司。截至2012年底,新星石油公司地热供暖能力达1000×10^4m2,约占全国常规地热供暖面积的25％。今后中国石化应逐步拓展地热能利用范围。延伸地热能利用产业链;加强科研攻关,积极创新,促进地热开发利用关键技术研发及推广应用;同时要加强国际交流与合作,加快地热开发利用技术的制度建设,并积极争取国家、地方的优惠政策和支持,推动我国地热产业快速健康发展。     

Experience in developing and utilizing geothermal resources in iceland

Geothermal energy plays a larger role in the energy economy of Iceland than in any other country-Iceland is The Geothermal Country. This development dates back to 1930, when the first district heating system was started in Reykjavik, and since then geothermal water and steam have been utilized for a broad range of applications. Iceland has seen an unprecedented activity of geothermal projects over the past decade; geothermal district heating systems being installed wherever possible in cities and rural areas, a 30 MW_e, electric power plant at Krafla, small scale production of salt and carbon dioxide, heat extracted from the newly erupted lava in the Westman Islands for district, heating, increased use in industry and agriculture, and now recently an explosive development in fish farming. For a number of years the investment in geothermal projects represented 1.5% of the gross national product of Iceland.The largest use of geothermal energy in Iceland is for space heating and domestic use. At the moment 85% of all houses in the country are heated with geothermal water. This is of great importance in a country where heating is required practically throughout the year. The climate is rather temperate ranging from −15 to +20°C, and with the building codes now in effect that call for double and triple glazing and 150–200 mm of roof insulation, heating demand is 20 W/m³ and the annual usage 60–80 kWh/m³. Heating of greenhouses, industrial drying, fish farming, swimming pools, chemical production and electric power generation also make use of this energy source.This development has on the whole been very successful from the economic and technical standpoint, and has contributed to the wellbeing of the population of some 240,000 persons.This review paper will focus on some of the engineering experience gained in harnessing this “unconventional” energy source.     

地热资源的开发利用及可持续发展

地热资源作为一种新型能源矿产,具有分布广泛、易于开发等特点,其利用方式主要有地热发电和地热直接利用两种.我国具有良好的地热资源条件,主要为中低温地热资源.据计算,我国12个主要沉积盆地的地热可开采资源量为7500×1018J,相当于2560×108t标煤.当前,我国地热资源利用方式主要以供暖、洗浴、种植等直接利用为主;地热发电发展缓慢,主要分布在西藏;利用热泵技术开发地热资源得到了快速发展;油区地热资源的开发利用也取得了良好的经济和社会效益.但同时我国地热资源产业也面临着一些问题,包括大部分地区尚未开展地热资源勘查评价,影响了地热资源规划的制订及地热产业的发展;防腐、防垢技术还需要进一步加强研究;地热回灌率普遍过低;增强型地热系统研究有待加强等.为了促进地热资源的可持续发展,建议在加大地热资源勘查力度的同时,应以浅层地温能和热水型地热资源为主,发挥热泵技术的优势,开展地热资源的综合利用及梯级利用;重视和加快油气区地热资源的利用;在西藏等适宜地区加大高温地热能发电利用;集中全国优势技术力量,在一两个有利区域开展增强型地热系统技术探索;此外,走回灌开发道路是地热资源开发利用的必然选择.     

Efficient utilization of waste heat from molten carbonate fuel cell in parabolic trough power plant for electricity and hydrogen coproduction

Direct steam generating parabolic trough power plant is an important technology to match future electric energy demand. One of the problems related to its emergence is energy storage. Solar-to-hydrogen is a promising technology for solar energy storage. Electrolysis is among the most processes of hydrogen production recently investigated. High temperature steam electrolysis is a clean process to efficiently produce hydrogen. In this paper, steam electrolysis process using solar energy is used to produce hydrogen. A heat recovery steam generator generates high temperature steam thanks to the molten carbonate fuel cell's waste heat. The analytical study investigates the energy efficiency of solar power plant, molten carbonate fuel cell and electrolyser. The impact of waste heat utilization on electricity and hydrogen generation is analysed. The results of calculations done with MATLAB software show that fuel cell produces 7.73 MWth of thermal energy at design conditions. 73.37 tonnes of hydrogen and 14.26 GWh of electricity are yearly produced. The annual energy efficiency of electrolyser is 70% while the annual mean electric efficiency of solar power plant is 18.30%.The proposed configuration based on the yearly electricity production and hydrogen generation has presented a good performance.     

The geothermal industry in Iceland

Direct (non-electrical) uses of geothermal energy in Iceland in 1984 amounted to 5517 GWh and the installed power was 889 MW_t, assuming 35°C discharge temperature. The bulk of this thermal power was for district heating, called hitaveita in Icelandic. In recent years this utilization has increased moderately. The installed geothermal electric power is currently 41 MW_e and is unlikely to change in the near future. Icelandic personnel have participated in many geothermal projects of the United Nations during the last 35 years. Contract work has been carried out by Icelandic consulting firms in several developing countries.     

Geothermal electric power in Iceland: Development in perspective

Geothermal energy is extensively used in thermal (direct) applications in Iceland. More than 70% of the total population enjoy geothermal district heating. Hydro-power provides most of the electricity generated in Iceland, with less than 10% of the potential harnessed. Iceland is well endowed with both geothermal (high- and low-temperature) and hydro-power resources. At the end of 1980, the installed geothermal power in Iceland was 818 MW₁ in direct applications and 41 MW_e in electric power generation. This exploitation represents a few percent of the estimated geothermal resources of Iceland. Plans to develop geothermal electric power in Iceland date back to the early 1960s. The first geothermal electric power plant (3 MW_e) was installed in 1969. In recent years, several small-scale (two 1 MW_e and one 6 MW_e) geothermal power units have been installed in a cogeneration plant for district heating purposes. There is one major (30 MW_e) geothermal electric power plant in Iceland, which became operational in 1978. Hydro-power, geothermal energy and oil provide consumers in Iceland with about 18, 38, and 44% of their energy needs, respectively.     

Present status of underground thermal utilization in Japan

Utilization of low-enthalpy geothermal energy in Japan, especially with the application of geothermal heat pumps, is far behind other industrial countries. In 1998, a feasibility study was made of utilizing Japan's low-enthalpy geothermal resources. Since 2001 the Geo-Heat Promotion Association of Japan (GeoHPJ) began its activities with the objective of installing 140,000 heat pump systems in private houses by the target year of 2010. The Geothermal Research Society of Japan has also launched new activities in this sector. Research groups in universities and other national institutes have started geoscientific research on the utilization of low-enthalpy resources and private, academic and governmental sectors have consequently begun promoting geothermal heat pump utilization.     

Industrial use of geothermal energy at the Tasman pulp & paper co. ltd's mill, Kawerau, New Zealand

Tasman Pulp & Paper Co. Ltd's mill at Kawerau has an annual production capacity of 380,000 tonnes of Newsprint and 200,000 tonnes of Kraft pulp. The mill electrical requirement amounts to 128MW. Geothermal steam has a significant impact on the mill energy balance and contributes around 35% of the mills steam requirements. There are five geothermal to clean steam heat exchangers with a total capacity of 140t/hr of 345kPa saturated process steam and two boiler feedwater heaters which supply two chemical recovery boilers and three power boilers. Additional geothermal steam is used to heat combustion air and operate shatter sprays at the recovery boilers. A 10MVA geothermal turbo-alternator exhausts steam to a black liquor pre-evaporator and a heat exchanger to heat clean process water. All the available geothermal condensate is collected and treated in a condensate recovery plant to meet quality specifications for boiler feedwater. This meets all of the feedwater requirements of the geothermal heat exchangers plus the make up for the recovery and power boilers. Geothermal water separated in the borefield is used by Bay of Plenty Electricity in two Ormat binary cycle turbines which generate 2.0MW nett. The discharge from the binary cycle plant is also processed in an experimental pilot scale Precipitated Silica plant to recover silca which is used as a newsprint additive. The remainder is discharged through a serpentine canal to the Tarawera river.     

Agriculture and aquaculture applications of geothermal energy

Agriculture and aquaculture applications are particularly attractive for geothermal applications because they require heating at the lower end of the temperature range where there is an abundance of geothermal resources. Use of waste heat or the cascading of geothermal energy from power plants or other high-temperature uses also have excellent possibilities. A number of agribusiness applications can be considered such as greenhouses, aquaculture, animal husbandry, soil warming and irrigation, mushroom raising and biogas generation.     

Development of geothermal energy utilization in Turkey: a review

Renewable energy is accepted as a key source for the future, not only for Turkey but also for the world. Turkey has a considerably high level of renewable energy sources that can be a part of the total energy network in the country. Turkey is located in the Mediterranean sector of Alpine–Himalayan Tectonic Belt and has a place among the first seven countries in the world in the abundance of geothermal resources. The share of its potential used is, however, only about 2–3%.The main objective of the present study is to review the development of geothermal energy (GE) utilization in Turkey, giving its historical development and opportunities. GE is used for electric power generation and direct utilization in Turkey, which is among the first five countries in the world in geothermal direct use applications. Direct use of geothermal resources has expanded rapidly last 36 years from space heating of single buildings to district heating, greenhouse heating, industrial usage, modern balneology and physical treatment facilities.Turkey presently has one operating geothermal power plant, located near Denizli City in Western Anatolia with an installed capacity of 20.4 MW_e and an electrical energy production of 89,597 MW h in 2001. Recently, the total installed capacity has reached 820 MW_t for direct use. The total area of geothermal heated greenhouses exceeded over 35 ha with a total heating capacity of 81 MW_t. Ground-source (or geothermal) heat pumps (GSHPs) have also been put on the Turkish market since 1998. Though there are no Turkish GSHP manufactures as yet, 207 units have been installed in the country to date, representing a total capacity of 3 MW.GE is a relatively benign energy source, displaying fossil fuels and thus reducing greenhouse gas emissions. So, it is expected that GE development will significantly speed up in the country if the geothermal law becomes effective.     

A review on the energy and exergy analysis of solar assisted heat pump systems

During the last decade, a number of studies have been conducted by various investigators in the design, modeling and testing of solar assisted heat pump systems (SAHPSs). This paper reviews the studies conducted on the energy and exergy analysis of SAHPS systems in Turkey and around the world as of the end of December 2004. The studies undertaken on the SAHPS systems are categorized into four groups as follows: (i) SAHPSs for water heating, (ii) SAHPSs with storage (conventional type) for space heating, (iii) SAHPSs with direct expansion for space heating, and (iv) Solar-assisted ground source heat pump greenhouse heating system (SAGSHPGHS). This paper investigates the studies on SAGSHPs, especially ground-source heat pumps, also known geothermal heat pumps, at the Turkish universities in more detail, by giving Turkey's solar energy potential.     

Economic evaluation of geothermal power generation,heating, and cooling

Economic analysis of a typical geothermal resource shows that potential revenues from geothermal heating or cooling can be much larger than those from power generation alone. Geothermal heating may generate up to about 3.1 times and geothermal absorption cooling 2.9 times as much revenue as power generation alone. Similarly, combined power generation and heating may generate about 2.1 times and combined power generation and cooling about 1.2 times as much revenue as power generation alone. Cost and payback period comparisons appear to favor power generation, followed by district heating.     

地热发电的投资经济分析

地热能是一种清洁的可再生能源,越来越多的国家宣布支持地热开发。地热发电必须考虑到影响成本的各种因素,地热发电的成本主要由初始投资和电力生产运行及维护成本两部分组成。地热项目具体的投资成本与资源特征和现场条件有着非常密切的关系,资源的温度、深度、化学特性和渗透性是影响发电成本的主要因素。与传统化石燃料发电相比,地热发电已具有相当的竞争力,在生命周期内地热发电厂的平均成本大大低于传统燃料发电厂。另外,地热发电还有抵消化石燃料价格波动对电力市场影响的作用,有利于促进农村和偏远地区经济发展,有利于能源供应多元化。当然,地热能发展也面临着一些障碍,包括钻井的成功率、地热技术尚不够完善以及项目启动成本高等。建议今后地热资源的利用不再仅局限于极少数高温地热项目中,而是尽可能发掘地热资源的所有潜力。