The increasing rate of industrialization and urbanization increases waste and wastewater generation along with global energy demand. That makes the necessity of the current waste treatment and process technologies to be upgraded into the sustainable or green energy generation such as hydrogen production from the waste materials and hydrogen fuel cells-based technologies. Fuel cells are electrochemical devices that use hydrogen as fuel cells for electricity or heat generation. The fuel cells-based technologies are in the infant stage and need to be explored for the vital utilization of hydrogen for the various energy related applications. Stationary application of fuel cells or hydrogen fuel cell vehicles related technologies are hotspot research areas in the 21st century. In this chapter, the authors summarize the recent development of the hydrogen production from waste, current state of the art in hydrogen fuel cells, and hydrogen fuel cell vehicles and their economic and sustainability benefits. It also includes the key challenges of these technologies for commercial applications.
TopIntroduction
Fast urbanization and industrialization utilizing the natural resources rapidly to meet the global energy demand that may generate the huge amount of waste and wastewater that are the global concern in the 21st century. Recent statistics imply that 3 billion people will be added as new energy utilizers in the existing energy consumers by the end of this century. Global primary energy demand (~0.55 quadrillion MJ) is increasing at a rate of 2.11% per year with a predictable total increase of 55% by 2050 as shown in Figure 1 (IEA, 2019).
Figure 1. Forecasts on world population and energy consumption
Around 75-85% of global energy consumption by conventional resources consists of petroleum (34%), coal (27%), and other natural gas (24%), which are non-sustainable in nature as well as generate huge amounts of waste and wastewater. A recent literature computed that high-income countries, upper-middle-income countries and low-income countries treat the generated wastewater by 70%, 38% and 8%, respectively (Jones et al., 2021). The increasing rate of pollutants and wastewater generation during the energy generation and utilization have adverse impacts on global climate, human health and ecosystems (Chaurasia, Shankar, et al., 2021a; Rani et al., 2017). Thus, there is an urgent need to generate clean and sustainable energy conversion technologies such as production of hydrogen from waste or wastewater to mitigate the future energy challenges. Also, the hydrogen production or hydrogen utilization technologies should be economical and sustainable.
Hydrogen possesses a high energy density such as 122-142 MJ/Kg that is three times with respect to gasoline (petrol or diesel) (Chaurasia & Mondal, 2022a; Singh Thakur et al., 2022). It also offers sustainable and regenerative stationery applications in the hydrogen fuelled vehicles. Recent literature reported that renewable energy supported by communities that reduce the use of crude oil and coal will drop to 40.5% and 36.7%, respectively by 2030 (Chaurasia et al., 2020, 2022b). As per the statistics reported in 2022, ~70 million tonnes per year of hydrogen produced across the globe in which 90% of hydrogen is produced by steam reforming and electrolysis technologies by refineries and industries. Hydrogen are mainly produced and consumed by refineries ~96% is derived from non-sustainable fuels that consists of ~48% from natural gas, 30% from hydrocarbons based refineries, 18% from coal and about 4% from electrolysis (Lamy & Millet, 2020). Moreover, these processes have several consequences that waste and waste generation and rapid utilization of natural resources. Till date the major share of hydrogen is derived from biological and electrochemical process such as steam reforming, bio-photolysis, photo-fermentation, dark fermentation, bio-electrochemical based system such as microbial electrolysis cells and fuel cells, photolysis and electrolysis (Chaurasia, Siwach, et al., 2021a; Kachroo et al., 2022a). The hydrogen derived from waste or wastewater feedstocks are sustainable in nature and offer several sustainable goals such as value-added products recovery, renewable incentives, and higher energy revenues.