Geothermal Fields of India

This chapter narrates about the geothermal potential fields of India. Here the four majors fields of India namely the NW-SE Himalayan Arc, North East Region, and Andaman Nicobar Islands, Son-Narmada-Tapti Lineament (So-Na-Ta), West Coast Continental Margin, Gondwana Graben. The major Himalayan arc includes geothermal fields like Puga, Chhumthang, Manikaran, Beas and Tapoban geothermal fields. The Son-Narmada-Tapti lineament includes geothermal fields like Tatapani, Salbardi, Anhoni-Samoni and Unkeshwar. The west coast continental margin has geothermal fields like cambay, northern and eastern Bombay offshore, konkan geothermal province along with Unai, Dholera and Gandhar. The chapter at last is concluded with the resource estimation and field development plan of the above-mentioned fields.

One of the major uses of geothermal water is power generation cycles. This chapter talks about the types of geothermal power generation cycles. This chapter talks about the types of steam generation cycles like flash steam, single flash steam cycle, double flash steam cycle and dry steam. Another most popular technique for low enthalpy geothermal energy is Binary cycles. This method has benefits like it optimises energy transfer by efficiently exchanging heat with the geothermal fluid through a heat exchanger. One of the other useful cycles is Kalina cycle. In thermodynamics, the Carnot cycle is recognised for its exceptional efficiency, which is characterised by zero heat losses. It functions as a zero-loss heat engine and consists of four reversible processes, including two isothermal and two adiabatic phases. The century-old Rankine cycle, which generates electricity by using water as the working fluid, closely resembles the Carnot cycle in practise. The chapter is concluded by the CO₂ cycle along with regeneration and combined cycles for power generation.

Geothermal power, a renewable energy source that harnesses the Earth's internal heat, has the capacity to generate electricity at a rate of around 15,000 TWh per year, exceeding global annual energy consumption. This chapter investigates the progress made in the field of geothermal power generation, hybridization, and storage, focusing on their potential contributions towards the advancement of a sustainable and environmentally conscious energy environment. Flash steam, dry steam and binary-cycle power plants are widely recognized as the predominant categories of geothermal power generation. The incorporation of wind, solar, and biomass energy into geothermal power systems via hybridization improves power generation efficiency, operational flexibility, and resource utilization. When geothermal resources are scarce, combining solar or biomass power with geothermal energy may enhance energy generation. The use of geothermal energy storage is crucial for mitigating the intermittency challenge and ensuring the utilization of geothermal energy in response to fluctuating demand. Thermal energy storage involves the storage of heated water derived from geothermal reservoirs within insulated tanks or subsurface aquifers, with the intention of utilizing it at a later time. In the year 2021, the nations of the United States, Indonesia, and the Philippines collectively implemented the most amount of geothermal power, reaching a cumulative capacity of 15,372 MW. The integration of hybridization and storage technologies is facilitating the optimization of geothermal power generation, enabling the utilization of its full capacity and facilitating the transition to a more sustainable energy environment.

The agricultural sector, which heavily depends on water, must develop better water management techniques and look into possible ways to meet supply and demand due to issues related to water scarcity and the need for a profitable and sustainable agri-food chain. Geothermal groundwater can be used to create both electricity and heat. As a result of its high ionic content, harvested energy can be recovered and then used for irrigation. Most geothermal fields can be found in rural areas where farming is practiced. The energy expenditure of agricultural desalination is higher because of the necessity of additional post-treatment procedures. Meeting energy needs with fossil fuels is becoming increasingly costly, and its associated greenhouse gas emissions are damaging the environment. This highlights the need to work to incorporate non-conventional energy sources into the desalination process. The use of geothermal heat for desalinating water is a renewable energy source that is thoroughly examined in this chapter. The introduction of possible geothermal energy integration with desalination technologies is also covered, along with the desalination of geothermal water for irrigation.

There are several applications of geothermal water in form of direct and indirect form of utilization. This chapter talks about the applications which are going to be helpful in terms of societal benefits. Some popular societal benefits are Honey processing, milk pasteurization and greenhouse gas emissions. The designing and working principals of the societal benefits models are described in detail. A new Concept of Climate Battery: A ground to air heat transfer method has been introduced. The methods of societal benefits discussed in this chapter will not only help to understand the technology in detail, but it can also lead to several employment opportunities.

There are several metals, base metals and rare earth elements which can be extracted using geothermal water. This chapter talks about such methods which helps to extract individual type of elements. The most popular methods are adsorption, ion exchange, solvent extraction, molecular recognition technology and magnetic segregation. Some precious metals like gold and silver are extracted from geothermal energy using heap leaching method. Heap leaching is one of the cheapest method for gold and silver extraction. For silica extraction form geothermal energy is performed using cascade method. Whereas for helium and lithium recovery swing adsorption method is world widely accepted. Ion exchange method technique is applied for the zinc and manganese removal using geothermal water. The system ends with a note on hybrid approach for base metal and rare earth element extraction.

The integration of renewable energy sources like geothermal with the food production sectors could reduce dependence on fossil fuels and contribute to achieving Sustainable Development Goals (SDGs), specially focusing on food security and climate protection. Geothermal water can generate electricity and serve as a water supply, providing reliable access to clean water without impacting the environment. Despite its potential, geothermal energy is undervalued, making it underutilized in industrial processes. This chapter evaluates potential geothermal applications in the field of agriculture and agro-food sectors, including processing, cooking, oil extraction, drying, textile washing, pulp and paper processing, fuel generation, space heating, leather production, cooling, therapeutic balneology, and snow melting.

Geothermal resource assessment has always been a tricky affair. The assessment can be done at the several stages of the development which assures the stake holders investing in the project. In this chapter several methods of geothermal resource assessment have been discussed as per its application at different stages. Mostly the type of methods which are comely used are surface thermal flux, magmatic heat budget, total well flow, planar fracture method, lumped parameter modelling, power density/areal estimates, decline curve analysis, stored heat and numerical modelling. The most popular method for geothermal resource assessment is decline curve analysis. This method has had been regularly utilized to forecast prospective production. Another most reliable methods are volumetric analysis numerical modelling method for resource assessment. At the end in this chapter a section on application of AI and ML are used for resource assessment of geothermal energy.