‘Clean Energy and Water Technologies’ is now a social enterprise based in Melbourne, Australia. The purpose of this enterprise is to introduce a zero emission technology developed and patented by Ahilan Raman, the inventor of the technology. A 25 Mw demonstration plant will be installed to show case the above technology. This platform also used as a blog will publish articles relevant to Zero emission technologies for power and Zero liquid discharge technologies for water industries.
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.
With recent announcement of the prestigious award to NREL (National renewable energy laboratory, USA) for developing SJ3 solar cells along with their industrial partner Solar Junction, there is a new hope and expectation that PV solar will become a major source of clean energy of the future.Togather with Hydrogen as an energy carrier, the PV solar hydrogen will certainly be a game changer. With increasing efficiency of solar panel from 17.24% up to 50%, and generating high pressure hydrogen using improved solid polymer electrolyzer, the sun and water will become the future source of clean energy replacing our decade long dependency on fossil fuel. There is also a distinct possibility of converting water into hydrogen by direct sunlight using photo-electrolysis as explained in my previous article, “Can we duplicate Nature’s photosynthesis for Hydrogen production?”’ dated April 2,2012.
SJ3 solar cell uses tunable band gaps, lattice matched architecture with ultra-concentration tunnel junction to achieve the highest conversion efficiency of 43.5% with a possibility to reach an efficiency of 50%.This conversion efficiency is the percentage amount of solar energy converted directly into electrical energy. Such a high efficiency is due to the lens focusing the sunlight with 418 times intensity of the sun. There is no additional cost involved except the bottom Germanium layer of three junctions with Gallium and a dash of dilute nitride alloy. This small change boosts the bottom band-gap from 0.67 eV (electron volts) to 1.0 eV.The three layered SJ3 cell captures various frequencies of sunlight at various times and conditions achieving the best efficiency of converting photons to electrons.
High pressure PEM Hydrogen generators producing 99.99% purity Hydrogen at elevated pressures are already under development. With carbon fiber storage tanks up to 10,000 psi pressure ratings, Fuel cell cars will become commercial reality overtaking Lithium battery powered electrical vehicles.PV solar Hydrogen will significantly alter the transportation and stationary power generation industries in the future simply because hydrogen has the highest heat value and it is absolutely clean.
Age old centralized power plants using fossil fuels with highest carbon emission and water consumption has created serious environmental problems all over the world. Coastal power plants discharge huge amount of ‘once through’ cooling water into the sea at higher temperature and at higher salinity.Tranasport industries using fossil fuels emit high greenhouse gases due to age old, inefficient combustion engines causing global warming. Low humidity, high surface temperatures, dry conditions and lightning are perfect combination of conditions for bush fires similar to the one witnessed in Colorado mountain ranges.
It is a right time to adopt distributed energy systems so that individual houses and business can generate their own power using PV solar and wind Hydrogen with no transmission grids and grid failures. It is time to replace fossil fuel with sun’s light and pure water so that we can hope for a cleaner future. We have all the necessary technologies and we need a will and concerted effort to make these changes.