Abstract
Industrial revolution and sustainable development have intensified the need for clean resources of energy. Among all the possible alternative sources of green energy, hydrogen energy is the most promising one because of its abundancy, maximum energy density per unit mass, and clean combustion. The energy content per unit mass of hydrogen is estimated to be the highest among all known chemical fuels. Therefore, it has enough potential to meet the rising energy demand if some major barriers in its production, storage, and effective commercial or vehicular use are resolved efficiently. One of the most significant challenges in the development of a global hydrogen-based economy is the hydrogen storage problem, which essentially means minimizing the enormous volume of hydrogen gas to achieve optimum gravimetric and volumetric density synergistically. This chapter briefly discusses the significant challenges, especially the hydrogen storage problem in the path of the development of a hydrogen-based economy and the possible approaches to meet the challenges.
TopIntroduction
The past two centuries have been marked by technical breakthroughs, rapid globalization, and the industrial revolution, which have enhanced our living standards and reliance on technology (De Vries, 1994). These global advancements, population growth, and the need for sustainable development have significantly increased our energy demand, which has now reached approximately 15 Terawatt (Smalley, 2005). In this era of technology and digitalization, the per capita demand for energy has increased exponentially, thereby intensifying our need for additional energy resources. Till today, fossil fuels like coal, petroleum, diesel, etc. are the prime sources of energy and approximately 85% of the global energy (Abbott, 2009) needs are fulfilled by them, as depicted in Figure1(a). The formation rate of fossil fuels is slower than their consumption rate, resulting in their rapid depletion; therefore, there is a high probability that they will run out within the next few decades. In addition, day by day increase in energy demand, wastage and improper use of energy, less exploration and minimal use of renewable sources of energy has brought about a serious shortage of energy often called as energy crisis (Dudley, 2018). Energy crisis basically means that our global energy demand exceeds the amount of prime energy reserve and this ratio is getting higher and higher with the passage of time because of the above outlined reasons. Therefore, we must urgently look for some renewable energy sources that can effectively replace fossil fuels and satisfy our increasing energy needs. In addition, the green-house gases such as carbon monoxide, carbon dioxide, and methane produced by the combustion of fossil fuels trap solar heat in the earth's atmosphere, resulting in global warming and environmental temperature imbalance (Coyle & Simmons, 2014).
Figure 1. (a) Percentage contribution of different energy sources used to meet global energy demand; (b) global average temperature rise with year (datasets obtained from NASA, NOAA, Berkeley Earth, and meteorological offices of the U.K. and Japan)
Key Terms in this Chapter
Volumetric Density: Mass per unit volume.
Carbon-Free: Free of carbon containing compounds.
Gravimetric Density: The available energy per unit mass of a substance.
Hydrogen Storage: Storage of hydrogen.
Energy Density: Amount of energy stored in a given system per unit volume.
Nanocluster: A collection of few atoms.
Green Energy: Energy generated from natural resources.
Renewable: Able to be renewed by natural processes.
Critical Temperature: The highest temperature at which the substance can exist as a liquid.