Abstract
Hydrogen (H2) is an energy carrier that offers both some of the benefits of fossil fuels and is clean with a low carbon footprint. Production of H2 from the water electrolysis using renewable energy is called green hydrogen and is the preferred pathway for future H2 production. In order to decarbonize the energy sector, green hydrogen must be adapted to existing systems using different technologies. Fuel cells, gas turbines (GTs), and combined heat and power (CHP) systems are the primary applications for hydrogen in power generation. CHP systems are highly efficient and can be employed in buildings, industrial facilities, and district energy systems to provide electrical and thermal energy. Heat pumps integrated with fuel cells are another example of energy-efficient technology. Mixing hydrogen in a specific volumetric ratio improves the resource utilization of the present natural gas heating systems. This chapter focuses on green hydrogen practices in electrical and thermal energy generation applications.
TopIntroduction
Governments and the media warn that there will be severe problems with energy supply to citizens in all countries and that the situation is concerning. Energy supply has been a concern due to the widespread usage of hydrocarbon-based fossil fuels, which are depleting. Fossil fuels are nonrenewable resources, and recent natural occurrences around the world have been linked to the detrimental impacts of fossil fuels on the climate. This condition increases psychological stress and lowers people's quality of life. Among the different alternatives proposed by scientists and experts, hydrogen technology is the most widely accepted. For this reason, the terms “hydrogen society” and “hydrogen economy” have recently gained prominence.
Hydrogen societies rely on reducing the use of fossil fuels in favor of emission-free sources and hydrogen-based generation to decarbonize energy systems. The hydrogen economy is described as a new industry that will create new jobs, contribute to reducing energy consumption and emissions, and stimulate economic growth (Dou et al., 2017). The hydrogen economy aims to generate significant amounts of power and hydrogen using primary energy sources such as solar, nuclear, and even fossil fuels (Sherif et al., 2014). Industrial and political milestones have arisen for the hydrogen economy, which are linked and will shift in relative importance over time. The following milestones are being considered: a) hydrogen from coal; b) hydrogen as a transportation fuel; c) the exergetically efficient stationary fuel cell; d) hydrogen and fuel cell-induced industry structure change; e) political framework conditions for investment planning security (Winter, 2005). Many countries are developing hydrogen strategies or roadmaps to encourage their citizens to accept hydrogen technology and ensure the growth of the hydrogen economy.
Hydrogen is an energy carrier with the highest energy content per weight. Hydrogen is a unique energy carrier due to its excellent qualities, which are detailed below:
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It can both produce and convert electricity with high efficiency.
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It is produced using water, which is a plentiful raw material on the planet.
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It is a renewable fuel.
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It can be stored in gaseous form for large-scale storage, in liquid form for air and space transportation, and as metal hydrides for cars and small-scale storage.
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Long-distance transportation can be accomplished by using pipelines or tankers.
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Catalytic combustion, electrochemical conversion, and hydration are all efficient methods for converting it into other types of energy.
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It emits no greenhouse gases (GHG) or other pollutants into the environment during manufacture, storage, transportation, or consumption (Sherif et al., 2014).
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So far, hydrogen has been produced using coal, crude oil, or natural gas, resulting in an unclean production technique with GHG emissions. Today, hydrogen synthesis by electrolysis of water using only renewable electricity is called “green hydrogen” and is encouraged.
Key Terms in this Chapter
Fuel Cell: Fuel cells are a clean energy conversion technology that can generate electrical energy directly from the chemical energy of the fuel.
Combined Heat and Power (CHP) System: In these systems, also called cogeneration, heat and electrical energy are produced simultaneously, where heat production is the limiting factor for energy efficiency.
Coefficient of Performance (COP): The COP value, which determines the performance of a heat pump or cooling system, is the heating or cooling rate achieved in response to the work done.
Natural Gas Blending: It is blending clean hydrogen with natural gas in some proportions in the existing pipe system to reduce greenhouse gas emissions.
Wobbe Index: It is an index that compares the combustion energy outputs of gas fuels with different compositions.
Electrolysis: The electrolysis process is the decomposition of water by giving hydrogen and oxygen gas through externally supplied electrical energy.
Heat Pump: It is equipment that transfers heat from a low-temperature environment to a high-temperature environment with externally supplied electrical energy.
Gas Turbine (GT): Gas turbines, which work according to the Brayton cycle principle, produce power by rotating a turbine due to the expansion of compressed, high-heated air.
Greenhouse Gas (GHG): A greenhouse gas is characterized by its ability to absorb infrared radiation, capturing and re-emitting heat energy from the Earth's surface.
Green Hydrogen: It is the hydrogen obtained from electrolysis powered by renewable energy sources accepted as the principal production route.