Google analytics tag

Showing posts with label Carbon pollution reduction. Show all posts
Showing posts with label Carbon pollution reduction. Show all posts

Wednesday, January 6, 2016

Which car Hydrogen, Fuel cell or Electric that will win the race?


Automobile industry has come a long way since the time of Henry Ford. The internal combustion engine that drives the modern car is slowly but steadily evolving into an emission free engine. The carbon pollution has caused globe to warm and changed the climate and also caused respiratory illness for millions of people around the world for decades. The Carbon pollution was completely ignored in the past while other design features of the car have undergone massive changes. However, when the smog and deteriorating air quality of Delhi and Beijing was beamed around the world in our TV sets, people realized how vulnerable they are to carbon pollution. But how to eliminate the Carbon emission from our automobiles? 1.The simple answer is to substitute the fossil fuels we use every day such as Petrol and Diesel with Carbon free fuel such as Hydrogen. Hydrogen being a light gas it has to be compressed and liquefied so that it can occupy less space. However, it requires a special ‘cryogenic tank’ to store liquid Hydrogen at – 253 C. BMW has already produced a commercial vehicle and it is in the market. However, the Hydrogen dispensing stations are limited in numbers. It uses existing internal combustion engine suitably modified for Hydrogen fuel so that they can use existing infrastructure that produces their petrol engines. There is no carbon emission except for water vapour. However, Hydrogen should be generated using renewable energy sources such as solar or wind. Hydrogen generated by reformation of natural gas will still have a Carbon foot print. It can be classified as a Carbon free car depending upon how Hydrogen is generated. However, producing liquid hydrogen or filling in a cryogenic tank is not commercially feasible for individual household. Hydrogen supply will have to be a centralized filling station. BMW has recently focussing their attention towards Fuel cell car. While those early vehicles were fun to drive, they suffered from the inefficiencies of super-cooling the liquefied hydrogen, and the hydrogen vaporizing in storage. Around the turn of the century, BMW began to research the hydrogen-powered, fuel-cell electric vehicle as an alternative to the hydrogen-powered combustion engine. 2.The other alternative is to substitute fossil fuel with compressed Hydrogen that generates an electric power using Fuel cell that drives the motor and the car. Here both fossil fuel and internal combustion engine are substituted with Hydrogen fuel and Fuel cell. This is a marked deviation from a conventional car. Honda of Japan was the first to introduce a commercial car using a Fuel cell. It uses compressed Hydrogen at 70 Mpa pressure that supplies Hydrogen to PEM (proton exchange membrane) Fuel cell that generates power that drives the motor and the car. There is no emission except for water vapour. The car runs smoothly and silently because there is no mechanical engine or moving part. It is truly a Carbon free car if the Hydrogen is generated from a renewable energy source such as solar or wind. It is ideal for houses with roof top solar panels. However, one has to install a water purifier, an electrolyser, a compressor and a compressed tank for Hydrogen storage. If the Hydrogen is generated by steam reforming of Natural gas, then it will have a Carbon footprint and cannot be classified as carbon free car. Generation of Hydrogen using roof top solar panel, electrolysis and compression is possible by individual households but it involves still some risk due to the explosive nature of Hydrogen. A centralized Hydrogen dispensing is still a safer method. Toyota Mirai Fuel cell car is a new model introduced by Toyota motor Co of Japan. It too has certain additional features such as a power generator for a remote households or camps. 2.The third alternative is to eliminate fuel as well as the engine completely; instead supply power to the motor from a storage battery. Here there is no emission or noise because there is no engine or moving parts similar to Fuel cell car. However, the battery is heavy and occupies a large space and it requires frequent charging from an external power source. The power often comes from the main power grid which carries the power generated from a power station which invariably uses fossil fuel. Though there is no Carbon emission from the electric car it still has Carbon footprint. However, if the power is generated from a renewable energy source such as solar and wind then it can be classified as Carbon free car. It is ideal for houses with roof top solar panels. However, it should be connected to the power grid in parallel. Alternatively, it can be connected to a storage battery if there is no grid. The Lithium ion battery pack in Tesla Roadster weighs 990 pounds, stores 56 kWh of electric energy, and delivers up to 215 kW of electric power. Tesla battery packs have the highest energy density in the industry. To achieve this energy density, Tesla starts with thousands of best-in-class Lithium-ion cells and assembles them into a liquid-cooled battery pack, wrapped in a strong metal enclosure. The battery is optimized for performance, safety, longevity, and cost. The cells used in a Roadster employ an ideal chemistry for electric vehicles Nickel Metal Hydride (NiMH) batteries are commonly used in hybrid cars. However, a 56 kWh NiMH battery pack would weigh over twice as much as the Roadster battery. Instead, Tesla uses Li-ion battery cells which dramatically decrease the weight of the Roadster pack and improve acceleration, handling, and range.
With Lithium-ion chemistry, there is no need to drain the battery before recharging - there is no “memory effect”. Roadster owners simply "top-off" each night.However long term supply of Lithium is still an issue. Each of the above cars have their own advantages and disadvantages. However, Fuel cell cars have certain advantages over Electric cars in spite of the advancement in battery technology primarily due to the weight of the battery and frequency and time required to charge the battery. Fuel cell car has a capacity to store Hydrogen fuel as well as to generate power onsite and this advantage will go a long way to make fuel cell cars truly carbon free not only for transportation but also for stationery power generation in remote locations. A large scale deployment of renewable energy generation such as solar and wind around the world can deliver a Car that is truly carbon free. However fossil fuel power generation will continue for years to come as the new technologies are developed to generate power using fossil fuel without emitting Carbon emission such as Carbon recycling. The real winner of the car race will depend upon how a Carbon emission free power generation technology will emerge in the future. Whatever may the power technology Fuel cell will be here to stay and if a cheap alternative catalyst is developed for Fuel cell then the race will be well and truly on. (Ref : Honda, Toyota and Roadster websites)

Thursday, April 18, 2013

Water and Energy are two sides of the same coin

Water and energy are two critical issues that will determine the future of humanity on the planet earth. They determine the security of a nation and that is why there is an increasing competition among nations to achieve self-sufficiency in fresh water and clean energy. But these issues are global issues and we need collective global solutions. In a globalised world the carbon emission of one nation or the effluent discharged into the sea from a desalination plant changes the climate of the planet and affects the entire humanity. It is not just a problem of one nation but a problem of the world. The rich and powerful nations should not pollute the earth, air and sea indiscriminately, hoping to achieve self-sufficiency for themselves at the cost of other nations. It is very short sighted policy. Such policies are doomed to fail over a period of time. Next generation will pay the price for such policies. Industrialised countries and oil rich countries should spend their resources on research and development than on weapons and invent new and innovative solutions to address some of the global problems such as energy and water. With increasing population and industrialisation the demand for energy and water is increasing exponentially. But the resources are finite. It is absolutely essential that we conserve them, use them efficiently and recycle them wherever possible so that humanity can survive with dignity and in peace. It is possible only by innovation that follows ‘Nature’s path. The earth’s climate is changing rapidly with unpredictable consequences .Many of us are witnessing for the first time in our lives unusual weather patterns such as draughts, flash flooding, unprecedented snow falls, bush fires, disease and deaths. Although we consider them as natural phenomena there is an increasing intensity and frequency that tells us a different story. They are human induced and we human beings cause these unprecedented events. When scientists point out human beings cause the globe to warm there were scepticism. We never believed we were capable of changing the entire weather system of the globe. We underestimate our actions. By simply discharging effluent from our desalination plants into the sea, can we change the salinity of the ocean or by burning coal can we change the climate of the world? The answer is “Yes” according to science. Small and incremental pollution we cause to our air and water in everyday life have dramatic effects because we disturb the equilibrium of the Nature. In order to restore the equilibrium, Nature is forced to act by changing the climate whether we like it or not. Nature always maintains“equilibrium” that maintains perfect balance and harmony in the world. If any slight changes are made in the equilibrium by human beings then Nature will make sure such changes are countered by a corresponding change that will restore the equilibrium. This is a natural phenomenon. The changes we cause may be small or incremental but the cumulative effect of such changes spanning hundreds of years will affect the equilibrium dramatically. We depend on fossil fuels for our energy needs. These fossils were buried by Nature millions of years ago. But we dig deep into the earth, bring them to surface and use them to generate power, run our cars and heat our homes. Our appetite for fossil fuels increased exponentially as our population grew. We emitted Carbon into the atmosphere from burning fossil fuels for hundreds of years without many consequences. But the emissions have reached a limit that causes a shift in Nature’s equilibrium and Nature will certainly act to counter this shift and the consequences are changes in our weather system that we are currently witnessing. The only way to curtail further Carbon emission into the atmosphere is to capture the current Carbon emissions and convert them into a fuel so that we can recycle them for further power generations without adding fresh fossil fuel into the system while meeting our energy demands. We can convert Carbon emissions into a synthetic natural gas (SNG) by using Hydrogen derived from water. That is why I always believe ‘Water and energy are two sides of the same coin’. But cost of Hydrogen generation from water will be high and that is the price we will have to pay to compensate the changing climate. Sooner we do better will be the outcome for the world. In other word the cost of energy will certainly go up whether we price the Carbon by way of trading or impose Carbon tax or pay incentives for renewable energy or spend several billions of dollars for an innovative technology. There is no short cut. This is the reality of the situation. It will be very difficult for politicians to sell this concept to the public especially during election times but they will have no choice. Similarly serious shortage for fresh water in many parts of the world will force nations to desalinate seawater to meet their growing demand. Saudi Arabia one of the largest producers of desalinated water in the world is still planning for the highest capacity of 600,000m3/day. This plant will discharge almost 600,000 m3/day of effluent back into the sea with more than double the salinity of seawater. Over a period of time the salinity of seawater in the Gulf region has increased to almost 40% higher than it was a decade ago. What it means is their recovery of fresh water by desalination will decrease or their energy requirement will further increase. Any increase in salinity will further increase the fossil fuel consumption (which they have in plenty) will increase the Carbon emission. It is a vicious cycle and the entire world will have to pay the price for such consequences. Small island nations in pacific will bear the brunt of such consequences by inundation of seawater or they will simply disappear into the vast ocean. Recent study by NASA has clearly demonstrated the relationship between the increasing salinity of seawater and the climate change. According to Amber Jenkins Global Climate Change Jet Propulsion Laboratory: “We know that average sea levels have risen over the past century, and that global warming is to blame. But what is climate change doing to the saltiness, or salinity, of our oceans? This is an important question because big shifts in salinity could be a warning that more severe droughts and floods are on their way, or even that global warming is speeding up... Now, new research coming out of the United Kingdom (U.K.) suggests that the amount of salt in seawater is varying in direct response to man-made climate change. Working with colleagues to sift through data collected over the past 50 years, Peter Stott, head of climate monitoring and attribution at the Met Office in Exeter, England, studied whether or not human-induced climate change could be responsible for rises in salinity that have been recorded in the subtropical regions of the Atlantic Ocean, areas at latitudes immediately north and south of Earth’s tropics. By comparing the data to climate models that correct for naturally occurring salinity variations in the ocean, Stott has found that man-made global warming -- over and above any possible natural sources of global warming, such as carbon dioxide given off by volcanoes or increases in the heat output of the sun -- may be responsible for making parts of the North Atlantic Ocean more salty. Salinity levels are important for two reasons. First, along with temperature, they directly affect seawater density (salty water is denser than freshwater) and therefore the circulation of ocean currents from the tropics to the poles. These currents control how heat is carried within the oceans and ultimately regulate the world’s climate. Second, sea surface salinity is intimately linked to Earth’s overall water cycle and to how much freshwater leaves and enters the oceans through evaporation and precipitation. Measuring salinity is one way to probe the water cycle in greater detail.” It is absolutely clear that the way we generate power from fossil fuels and the water we generate from desalination of seawater cannot be continued as business as usual but requires an innovation. New technologies to generate power without emitting Carbon into the atmosphere and generating fresh water from seawater without dumping the highly saline effluent back into the sea will determine the future of our planet. Discharge of concentrated brine into sea will wipe out the entire fish population in the region. The consequences are dire. Oil rich countries should spend on Research and Developments and find innovative ways of desalinating seawater with zero discharge of effluent instead of investing massively on decades old technologies and changing the chemistry of the ocean and the climate forever.

Friday, January 4, 2013

Heating and cooling buildings with solar heat.

Air conditioning makes up bulk of the power usage especially in tropical countries where the sun is shining almost throughout the year and the humidity levels are high. It makes a perfect sense to use solar heat to cool homes, business and factories. Many air-conditioning systems are commercially available using simple roof top PV solar panels to generate electric power to run an electric window air-conditioners. This system uses commercially available solar panels and window air-conditioners and uses solar power to generate electricity to run the compressor and the blower in the air-con unit. This system requires large storage battery to store adequate electricity to run your air-conditioners for specified period of time. Otherwise it requires a large area of solar panels to meet the demand. The efficiency of such systems can be improved using DC operated compressors and fans. However, renewable energy such as solar is still expensive to run air-conditioners because of high initial investment cost, though it may be economical in the long run as the cost of solar panels and accessories slowly come down over a period of time. Moreover such systems are limited to small air condition capacities. For large air-conditioning requirements such as business and factories, we require a system that uses solar heat directly to air-condition the premises with higher efficiency and thermal storage capabilities. Designing such a system is not very difficult because most of the components necessary to install such a systems are readily available. One can install an air-conditioning system based on 100% solar thermal heat with molten salt thermal storage. Alternatively, a hybrid system can be installed based on solar heat without a thermal storage but using city gas supply. Many countries use gas for heating during winter seasons but do not use gas during summer. These countries can use a hybrid (solar-gas) system to air-condition their premises and avoid peak electric usage during summer seasons thereby avoiding electrical black-outs. The advantage with such system is they can also be used for heating the premises during winter season. With changing climate due to global warming many warm countries like India also experiences cold temperatures during winter season. For example New Delhi in India has experienced a sharp drop in temperature up to 15-20c during winter from earlier winters. Solar cooling systems to date have used waste heat gas absorption chiller heaters, which utilize the waste heat from co-
generation systems (CGS) for the cold water. However, these chiller heaters with their established technologies are devices designed for the effective use of stable CGS high-temperature waste heat, so they cannot accommodate the preferential use of solar heat when solar hot water temperatures suddenly change from large variations in the heat collector temperatures due to changes in the weather. The new solar absorption chiller heaters are now specially designed for the effective use of low-temperature solar heat to address this problem and improve the energy conservation effect from solar cooling system. Hot water at less than 90C can be used for such systems and typical chillers with their rated specification are shown in the figures. The efficiency of the system can be vastly improved by using parabolic solar concentrators, up to 27 times higher than ordinary flat plate solar collectors resulting in conversion efficiency up to 85% in heating and cooling. By selecting a natural refrigerant such as R717 we can save the environment from ozone depletion. Such systems offers flexibility to use exhaust heat, natural gas along with solar thermal storage up to 220C (phase transition temperature).The system offers an attractive return on investment, electricity savings and Carbon pollution reduction. The system can be designed from 5TR up to 200TR refrigeration capacity for 100% solar and up to 1000TR for a solar-gas hybrid systems. The solar thermal system with molten salt storage is versatile in its application because the same system can be designed for heating or cooling or on-site power generation for continuous applications. .