Battery versus Hydrogen

The technology towards zero Carbon emissions from transportation has gained importance due to increasing air pollution from automobiles. It is not just the Carbon emission but oxides of Nitrogen and Sulphur, but also water vapour (more potent Greenhouse gas) to gather with particulate matters that compounds the emission problems. Current automobiles based on Internal combustion is not only energy inefficient but generates noise and air pollution. Therefore, battery cars and Hydrogen cars are increasing in popularity and competing with each other. We can examine the merits and demerits of these two technology for a better understanding. Transportation uses mechanical energy derived from thermal energy generated by combustion of fossil fuels but battery cars as well as hydrogen cars convert an electrochemical energy into mechanical energy. As we know energy can neither be created not destroyed but can be converted from one form to another form. The word “energy storage” is a misnomer because electrical energy is generated at the point of usage from stored chemicals by way of redox reactions. In both cases, we generate electrical energy from batteries or from Hydrogen through Fuel cell and then convert it into mechanical energy. Both battery as well as Fuel cell convert chemical energy into electrical energy by electro-chemical reaction namely redox reactions. For a redox reaction, we need both reduction (reductant) and oxidation (oxidant) reactions to take place simultaneously to effect flow of electrons from corresponding ions which we call electricity. It is clear from the above we need two reactants namely reductant and oxidant. In batteries both the reactant and oxidant are stored in solid form or in a liquid form in ‘flow batteries’. The chemistry of the redox reaction will determine the speed, size and the life of the battery. This creates a constraint on the size, weight and life of the battery to achieve a specific mileage. It means battery has a limitation when comes to size, life and mileage to be achieved. Tesla is currently leading the way in batteries both for stationery as well as transport applications. For stationery applications the space, weight and life may not be a big constraint but the life is a constraint and therefore the cost. But in transport applications all the above three parameters are critical and therefore battery may not be a long-term solution. In Hydrogen Cars Hydrogen gas is stored in a compressed form at high pressure in a cylinder. There is no Oxygen storage but only air is used as the Oxidant. Fuel cell uses both Hydrogen and Oxygen to generate electrical energy at the point of usage to run the motor. Electricity is not stored. The main difference between battery and fuel cell is, battery carries both Oxidant as well as reductant on board in solid form which weighs and occupies space; Fuel cell carries only Hydrogen as the reductant in gaseous form and not Oxidant. Hydrogen is a light weight and only the storage tank in the form of composite material is the actual weight. Moreover, there is more room to store Hydrogen like a Hydrogen bus which carries cylinders at the roof top. If we use renewable energy source such as solar and wind then Hydrogen generation and dispensing will not be a serious constraint for Hydrogen generation and distribution in the future. The biggest disadvantage with Fuel cell is the cost due to expensive catalyst such as Platinum. Each technology has its own advantages and disadvantages but the fundamental facts of these technologies will give us a glimpse of the future potential. In battery technology storing the reactants in solid form is an issue. Air metal battery has a good potential yet a long way to go. Similarly, if Hydrogen can be generated at the point of usage without storing Hydrogen on board that will open a greater potential. There may a hybrid solution in the future that can integrates both battery and Hydrogen- Fuel cell technologies will be the way forward. Research is being carried out to design a rechargeable Fuel cell battery with enhanced performance and cyclability. Such technologies will also guarantee a clean renewable energy storage technologies for stationery applications in the future. Hydrogen can be derived from many abundant natural sources such as seawater as I have explained in my previous article “CAPZ desalination technology uses only sun, sea and wind”.

Many people argue that Hydrogen is not an energy source but an energy carrier. Hydrogen is certainly an energy source by itself but is to be derived from other primary sources such as water or natural gas because Hydrogen is not available in a free form. Generation of Hydrogen from its sources require an additional energy but when such an energy is provided by renewable sources such as sun, wind and sea then the cost becomes secondary in the long run. Therefore, battery may not be able to compete with hydrogen in the long run though it provides a temporary solution to pressing power problems in short term. Moreover, batteries rely on materials like Lithium whose availability is limited even though they are recyclable.

Rare earth materials and Renewable

As the threat of global warming looms large, Governments and Industries are looking for innovative, alternative and renewable energy sources and energy efficiency solutions. But how many alternative energy sources are available and what are their potentials? How to reduce our carbon footprint without making larger new investment? How to improve the energy efficiency of the existing systems so that we can increase energy output for the same amount of fuel input and cut the cost of energy? These are some of the fundamental questions Governments and industries are grappling with, for the past few years. We are used to generating cheap energy from coal, oil and gas at the expense of the environment for several decades. We are used to water supply free of cost or at negligible cost for several decades. Governments were able to survive year after year because they were able to supply these two fundamental requirements of the people namely, energy and water at low cost. But this situation changed swiftly when scientists raised the alarm bells on carbon emission and global warming. Still many Governments, especially industrialized countries with large energy and water usage, are still playing ‘wait and watch’ game, because they cannot afford to increase the tariffs on power and water. Any such increase will make Governments unpopular and their re-election to the office doubtful. The real alternative to fossil fuels is only solar energy, which is clean, reliable and abundant. All other forms of renewable sources such as wind, geothermal, ocean thermal energy and wave energy are only offshoot of solar energy. The prime source is still the sun and the source of energy is from the chain nuclear fusion reaction of Hydrogen atom. The radiation of this nuclear reaction in the sun has to travel an average distance of 93 million miles to reach the earth, yet it is sufficient to meet current energy requirement of entire humanity by a factor of 20,000 times. But to convert sun’s light and heat energy into Electricity and other useful forms of energy, we require some rare materials which we never used in the past. They are called ‘rare earth materials’ because their available sources and supplies are rare on planet earth. But these exotic and rare earth materials are becoming indispensable in the development of renewable energy products and applications. The future growth of clean energy technologies depend on supply of such rare earth materials. Fourteen elements and related materials were selected for a criticality assessment by US Government department of energy. Eight of these are rare earth metals, which are valued for their unique magnetic, optical and catalyst properties. The materials are used in clean energy technologies as follows. Lanthanum, cerium, praseodymium, neodymium, cobalt and lithium are used in electric vehicle batteries. Neodymium, praseodymium and dysprosium are used in magnets for electric vehicles and wind turbines. Samarium is also used in magnets. Lanthanum, cerium, europium, terbium and yttrium are used in phosphors for energy-efficient lighting. Indium, gallium and tellurium are used in solar cells. The materials were selected for study based on factors contributing to risk of supply disruption. Though usage of such material is relatively small, it is anticipated that the growth of clean technologies will require a substantial quantity of these materials. Currently China is endowed with almost 95% of such rare materials in the world. These materials are available in the form of ores and minerals under the earth. They have to be mined, processed and extracted in a pure form so that they can be used in developing clean energy products of the future. We will discuss about such products and technologies in our future articles. The anomaly is the energy required to mine, process and extract these rare earth materials require energy and such energy has to come only from the sun. It is once again Nature that comes to the rescue of human beings at such critical junctures.