**3. Worldwide status of geothermal power production**

By the end of 2018, the cumulative global installed capacity of geothermal power amounted to 13.28 GW generated an annual electrical energy of about 86 TWh. Geothermal resource has contributed significantly in electricity production in some regions; 17% of New Zealand's electricity production and 31% of Iceland's electricity production was met by geothermal in 2018 [44]. In 2020, the global additions of geothermal capacity are estimated at 300 MW. Indonesia and Turkey led the new development, with 145 MW and 70 MW of capacity added for the two countries, respectively. The technology is forecast to reach 16.5 GW of aggregate capacity worldwide by 2022 [45]. While United Stated of America has been at the top world rank in terms of geothermal power capacity [46], Turkey, Kenya, Indonesia and the Philippines would be responsible for most of the technology growth and continue to lead capacity additions beyond 2022. Geothermal power cumulative capacity and additions in leading countries are depicted in **Figure 6** [44].

*Geothermal power capacity and additions in top countries by 2018 [44].*

Geothermal technology exploitation depends primarily on the resource potential and economic considerations, but generally, most existing geothermal facilities worldwide use flash or dry-steam technologies. However, on global scale, binarycycle technology has been the fastest progressing technology in recent time, due in part to rising utilization of relatively low-temperature resources [44]. Direct Use i.e., thermal energy consumption of geothermal energy technology is one of the common and versatile form of utilizing the underground heat [47]. The installed global total of geothermal power capacity for Direct Use sectors is estimated at 26 GWt at the end of 2018 [44].

The distribution of geothermal Direct Use applications is categorized as: 58.8% for heat pumps, 18% for bathing and swimming, 16% for space heating, 3.5% for greenhouse heating, 1.6% for industrial applications, 1.3% for raceway heating and aquaculture pond, while the remainder goes to other applications such as agricultural drying and snow melting and cooling, etc. [47]. Geothermal heat pumps have the greatest geothermal utilization worldwide, accounting for 59.2% of the annual energy use and 71.6% of the installed capacity by 2020. The installed capacity for geothermal based heat pumps approaching 77,547 MWt mostly built in North America, Europe and China. The size of individual systems ranges from 5.5 kW for residential installation to greater than 150 kW for commercial and institutional units [47]. Most heat pumps systems in Europe are sized for the heating load that are designed to meet the base load, with surging by fossil fuels. In Finland, as an example, some of these units reached an operation of up to 3,000 equivalent fullload heating hours per year i.e., a capacity factor of 0.34.

Space heating, including district heating and individual space heating, has now an installed capacity of 12,768 MWt and an annual energy use of 162,979 TJ/yr. In terms of annual energy use, the leaders are Turkey, Russia, Japan, the United States,


#### **Table 4.**

*MWt and leading states for various categories of direct-utilization for the year 2020 [4].*

#### *Geothermal Power Generation DOI: http://dx.doi.org/10.5772/intechopen.97423*

and Switzerland, accounting for about 75% of the world's individual space heating and nearly 90% of the world's total use in district heating. Deep Direct Use or what is alternatively called Cascaded Use offers large-scale viable systems that optimize the value stream of lower temperature resources through a multiple of purposes, from electricity production to direct cooling and heating, commercial and industrial applications, etc. [46]. **Table 4** provides a summary of the installed capacity factor (in MWt), and leading states for various categories of Direct Use for the year 2020.
