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Author Archives: ahilan@cewt.tech

Professional chemical engineer,specializing on clean energy and water technologies.He has more than 35 years of industrial experience in various process industries.Bulk of his experience were in R&D and commercialization.He has few innovative National and International patents on desalination and power generation. His latest patent is to store renewable energy such as solar, wind and geothermal in the form of SNG (synthetic natural gas) to generate base load power. You can eliminate the usage of fossil fuel and substitute with SNG with Zero Carbon emission. He is also a writer on Eastern philosophy, especially on Advaita Vedanta. He believes that science and Vedanta are two sides of the same coin. Science applies to this physical world, and it has its limitations. However, spirituality transcends science and the physical realm. It is your TRUE NATURE. Please check my LinkedIn profile.

Colloidal Coal Water Fuel by Nanotechnology for power generation

Coal is still the dominant fuel used for power generation due to its low-cost and abundant availability despite its emission problems and global warming issues. Companies around the world are trying to improve the efficiency of coal-fired power plants and cut emissions by various methods. The idea is to prepare an ultra clean coal with very low ash content in the form of coal-water slurry that can be directly injected into a diesel engine. Direct firing of coal requires micronising to less than 20-30 microns for diesel engine and less than 10 microns for turbines and producing a coal water slurry with at least 50% w/w coal content. The thermal and combustion efficiency of coal water fuel seems to be matching to that diesel engine at up to 1900rpm according to literatures. Still more research is required on engine modification and engine nozzle to handle coal water slurry because of its abrasive nature. If coal can be converted into a fluid like a diesel or Fuel oil then it can substitute diesel at reduced cost. However the Carbon problem needs to be addressed by ongoing research on sequestration.

Nanotechnology is an emerging field that offers hope to produce Colloidal coal water fuel that resembles fuel oil that may be suitable for direct injection into diesel engine with little modifications. The colloidal suspensions of coal in water (CCW) are produced using a proprietary wet-combination device. These suspensions are a new material with new properties.

“First, the colloidal fraction plus water is a pseudo fluid good for transport, handling and suspension of large particles. Second, the surface area per unit volume of coal available for chemical reaction and burning is greatly increased and finally, CCW may be milled with a third fluid, seeding the mixture with submicron coal. The colloidal nature of the majority of particles provides for very good features such as outstanding long-term stability, in contrast to regular coal water slurries (CWS) which rapidly sediment under storage. Moreover, the very small particles create an increased reactivity to combustion because small particles with large surface area react faster than large particles with the same volume.”

A company based in Panama has conducted experiments using colloidal coal water fuel and published the following information.

CCW suspension preparation and properties Characterization

“The colloidal dispersion are prepared in two stages: first by a bench mill and then by our wet- comminuting device. The bench mill was manufactured by IKA®- Group. After grinding,   samples were sieved using mesh size sieves 40 (400 μm), 70 (212 μm) or 140- (106 μm) and the passing particles were retained and used to prepare coal suspensions with various water contents (30 to 50 %), surfactants and other type of additives. These mesh sizes are not foreign to coal-fired power plants.  It is noteworthy that a preliminary formulation study is first necessary to decide the type and concentration of additives that are best suited to improve coal particle wetting and reduce viscosity. The additives were mostly surfactants and viscosity controlling agents and every type of coal tested usually required a specific formulation. In general, it was found that nonionic surfactants were good wetting agents, in concentrations varying from 0.1 to 0.6 w/w %. Some of the additives used to reduce viscosity by decreasing particle interactions, before or after the wet comminuting process, were amines. The suspension formulation previous to the wet-comminuting instance was very simple since what was basically required was a good wetting agent or a combination of two wetting agents. The idea was to have a uniform mixture with as low viscosity as possible.

Particle size of coal samples was determined by direct observation in an optical microscope, or by sieving using five or six different sieves ranging from 20 to 400 μm, or using a laser diffraction apparatus made by Microtrac Corporation, Nanotrac model, having a measurement range from 8 nm to 6.5 μm. Neither of these methods was sufficient to obtain a complete characterization of the particle size distributions, but a combination of the three allowed for a good assessment of what really was in the suspension, before and after the wet-comminuting process.

In our study, the percentage of mass passing the 635 mesh size sieve (< 20 μm) was used as an indicator of wet-comminuting process efficiency (generation of colloidal particles), given that microscopic observations generally showed that particles between 8 to 20 μm were very scarce. The preparation of the colloidal suspension of coal was centered in a technology that is totally based on fluid mechanics principles. As mentioned above, a preliminary suspension was prepared in a tank with low agitation and the appropriate water and surfactants contents. This suspension is then fed into a device that spins a film of the fluid to the walls of a cylindrical vessel at very high-speed and under cavitation free conditions. The resulting flow field induces a “particle trap” region where coal particles are locally concentrated above their nominal value and under very high shear. Particles are then milled to very small sizes by a wet-comminuting mechanism. Friction heating is controlled by a chilled water jacket around the vessel.

A schematic view of the set up is shown in the attached figure.

The energy consumed by the wet-comminuting device was evaluated by monitoring the power (voltage and amperage) during the process. The latter has two components, the power required to drive the motor shaft and mechanical seal, and the net power consumed by the fluid during comminuting. It was found that the net power divided by the mass flow rate, in terms of kWH/ton depended on coal content and viscosity of the preliminary slurry, exhibiting values of 30 to 80 kWh/ton. The energy consumed by the motor shaft and seal would account for 50 to 80 % of the total power consumed. Using the method described above, 100 gallons of CCW were prepared, using an Eastern bituminous coal that was previously grinded to 200 mesh. Several properties of this sample were characterized.”

Colloidal coal water fuel has certain distinct advantages over conventional coal water slurry for power generation using conventional diesel engine and turbines. Further research and development work is needed before it can be expanded for large-scale production. But it offers a hope to improve the efficiency of existing coal-fired power plants and reduces emissions.

Irreversibility leads to unsustainability

People in the chemical field will understand the concept of ‘irreversibility’. Certain chemical reactions can go only in one direction and but not in the reverse direction. But some reactions can go on either direction and we can manipulate such reactions to our advantages. This concept has been successfully used in designing many chemical reactions in the past and many innovative industrial and consumer products emerged out of it. But such irreversible reactions also have irreversible consequences because it can irreversibly damage the environment we live in. There is no way such damage can be reversed. That is why a new branch of science called ‘Green Chemistry’ is now emerging to address some of the damages caused by irreversible chemical reactions. It also helps to substitute many synthetic products with natural products. In the past many food colors were made out of coal-tar known as coal-tar dyes. These dyes are used even now in many commercial products. Most of such applications were merely based on commercial attractiveness rather than health issues. Many such products have deleterious health effects and few of them are carcinogenic. We learnt from past mistakes and moved on to new products with less health hazards. But the commercial world has grown into a power lobby who can even decide the fate of a country by influencing political leaders. Today our commercial and financial world has grown so powerful that they can even decides who can be the next president of a country rather than people and policies. They can even manipulate people’s opinion with powerful advertisements and propaganda tactics by flexing their financial muscles.

Combustion of fossil fuel is one such example of ‘irreversibility’ because once we combust coal, oil or  gas,  it will be decomposed into oxides of Carbon, oxide of  Nitrogen and also oxides of Sulfur and Phosphorous depending upon the source of fossil fuel  and purification methods used. These greenhouse gases once emitted into the atmosphere we cannot recover them back. Coal once combusted it is no longer a coal. This critical fact is going to decide our future world for generations to come. Can we bring back billions of tons of Carbon we already emitted into the atmosphere from the time of our industrial revolution? Politicians will pretend not to answer these question and financial and industries lobby will evade these question by highlighting the ‘advancement made by industrial revolutions’. People need electricity and they have neither time nor resources to find an alternative on their own. It is open and free for all. People can be skeptical about these issues because it is ‘inconvenient for them’ to change But can we sustain such a situation?

Irreversibility does not confine only to chemical reactions but also for the environment and sustainability because all are intricately interconnected.Minig industries have scared the earth, power plants polluted the air with greenhouse emission and chemical industries polluted water and these damages are irreversible. When minerals become metals, buried coal becomes power and water becomes toxic effluent then we leave behind an earth that will be uninhabitable for our future generations and all the living species in the world. Is it sustainable and can we call it progress and prosperity? Once we lose pristine Nature by our irreversible actions then that is a perfect recipe for a disaster and no science or technology can save human species from extinction. One need not be scientist to understand these simple facts of life. Each traditional land owners such as Aborigines of Australia or Indians of America and shamans of Indonesia have traditionally known and passed on their knowledge for generations. They too are slowly becoming extinct species in our scientific world because of our irreversible actions. Renewability is the key to sustainability because renewability does not cause irreversible damage to Nature.

Base load power generation with Solar thermal

 

All existing power generation technologies including nuclear power plants uses heat generation as a starting point. The heat is used to generate steam which acts as a motive force to run an alternator to produces electricity. We combust fossil fuels such as coal oil and gas to generate above heat which also emits greenhouse gases such as oxides of Carbon and Nitrogen. As I have disused in my earlier article, we did not develop a technology to generate heat without combusting a fossil fuel earlier. This was due to cheap and easy availability of fossil fuel. The potential danger of emitting greenhouse gases into the atmosphere was not realized until recently when scientists pointed out the consequences of carbon build up in the atmosphere. The growth of population and industries around the world pushed the demand for fossil fuels over a period which enhanced the Carbon build up in the atmosphere.

But now Concentrated Solar Power (CSP) systems have been developed to capture the heat of the sun more efficiently and the potential temperature of solar thermal can reach up to 550. This dramatic improvement is the efficiency of solar thermal has opened up new avenues of power generation as well as other applications. “CSP is being widely commercialized and the CSP market has seen about 740 MW of generating capacity added between 2007 and the end of 2010. More than half of this (about 478 MW) was installed during 2010, bringing the global total to 1095 MW. Spain added 400 MW in 2010, taking the global lead with a total of 632 MW, while the US ended the year with 509 MW after adding 78 MW, including two fossil–CSP hybrid plants”. (Ref: Wikipedia)

“CSP growth is expected to continue at a fast pace. As of April 2011, another 946 MW of capacity was under construction in Spain with total new capacity of 1,789 MW expected to be in operation by the end of 2013. A further 1.5 GW of parabolic-trough and power-tower plants were under construction in the US, and contracts signed for at least another 6.2 GW. Interest is also notable in North Africa and the Middle East, as well as India and China. The global market has been dominated by parabolic-trough plants, which account for 90 percent of CSP plants.As of 9 September 2009, the cost of building a CSP station was typically about US$2.50 to $4 per  watt, the fuel (the sun’s radiation) is free. Thus a 250 MW CSP station would have cost $600–1000 million to build. That works out to $0.12 to $0.18/kwt. New CSP stations may be economically competitive with fossil fuels. Nathaniel Bullard,” a solar analyst at Bloomberg

“New Energy Finance, has calculated that the cost of electricity at the Ivanpah Solar Power Facility, a project under construction in Southern California, will be lower than that from  photovoltaic power and about the same as that from natural gas  However, in November 2011, Google announced that they would not invest further in CSP projects due to the rapid price decline of photovoltaics. Google spent $168 million on Bright Source IRENA has published on June 2012 a series of studies titled: “Renewable Energy Cost Analysis”. The CSP study shows the cost of both building and operation of CSP plants. Costs are expected to decrease, but there are insufficient installations to clearly establish the learning curve. As of March 2012, there was 1.9 GW of CSP installed, with 1.8 GW of that being parabolic trough” Ref: Wikipedia.

One Canadian company has demonstrated to generate Hydrogen from water using a catalytic thermolysis using sun’s high temepertaure.The same company has also demonstrated generating base load power using conventional steam turbine by  CSP using parabolic troughs. They store sun’s thermal energy using a proprietary thermic fluid and use them during night times to generate continuous power. The company offers to set up CSP plants of various capacities from 15Mw up to 500Mw.

 

 

 

 

 

 

 

Solar Hydrogen for homes and cars.

Renewable Hydrogen offers the most potential energy source of the future for the following reasons. Hydrogen has the highest heat value compared to rest of the fossil fuels such as Diesel, petrol or butane. It does not emit any greenhouse gases on combustion. It can readily be generated from water using your roof mounted solar panels. The electrical efficiency of fuel cell using Hydrogen as a fuel is more than 55% compared to 35% with diesel or petrol engine. It is an ideal fuel that can be used for CHP applications. By properly designing a system for a home, one can generate power as well as use the waste heat to heat or air-condition your home. It offers complete independence from the grid and offers complete insulation from fluctuating oil and gas prices. By installing a renewable Hydrogen facility at your home, you can not only generate Electricity for your home but also fuel your Hydrogen car. The system can be easily automated so that it can take care of your complete power need as well as your fuel requirement for your Hydrogen car. Unlike Electric cars, you can fill two cylinders of a Hydrogen car which will give a mileage of 200miles.You can also charge your electric car with Fuel cell DC power.

Renewable Hydrogen can address all the problems we are currently facing with fossil fuel using centralized power generation and distribution. It will not generate any noise or create any pollution to the environment. It does not need large amount of water. With increasing efficiency of solar panels coming into the market the cost of renewable Hydrogen power will become competitive to grid power. Unlike photovoltaic power, the excess solar power is stored in the form of Hydrogen and there is no need for deep cycle batteries and its maintenance and disposal. It is a one step solution for all the energy problems each one of us is facing. The only drawback with any renewable energy source is its intermittent nature and it can be easily addressed by building enough storage capacity for Hydrogen. Storing large amount of energy is easy compared to battery storage.

The attached ‘You Tube’ video footage show how Solar Hydrogen can be used to power your home and fuel your Hydrogen car. Individual homes and business can be specifically designed based on their power and fuel requirements.

Global warming and man-made greenhouse gas.

There is a raging debate going on around the world especially in US about the global warming and its causes, among scientists and the public alike. When IPCC released its findings on the connection between greenhouse gas emission and the global warming and its disastrous consequences, there was an overwhelming disbelief and skepticism in many people. In fact many scientists are skeptical even now   about these findings and many of them published their own theories and models to prove their skepticism with elaborate ‘scientific explanations’.   I am not going into details whether greenhouse gas emission induced by human beings causes the globe to warm or not, but certainly we have emitted billions of  tons of Carbon in the form of Carbon dioxide into the atmosphere since industrial revolution. Bulk of these emissions is from power plants fueled by Coal, oil and gas. Why power plants emit so much Carbon into the atmosphere and why Governments around the world allow it in the first place?  When the emission of Oxide of Nitrogen and Sulfur are restricted by EPA why they did not restrict Oxides of carbon? The reason is very simple. They did not have a technology to generate heat without combustion and they did not have a technology to generate power without heat. It was the dawn of industrial revolution and steam engines were introduced using coal as a fuel. The discovery of steam engines was so great and nobody was disturbed by the black smoke it emitted. They knew very well that the efficiency of a steam engine was low as shown by Carnot cycle, yet steam engine was a new discovery and Governments were willing to condone Carbon emission. Governments were happy with steam engine because it could transport millions of people and goods in bulk across the country and Carbon emission was not at all an issue. Moreover carbon emission did not cause any problem like emission of oxides of Sulfur because it was odorless, colorless and it was emitted above the ground level away from human beings. However the effect of Carbon is insidious. Similarly, power generation technology was developed by converting thermal energy into electrical energy with a maximum efficiency of 33%.This means only 33% of the thermal energy released by combustion of coal is converted into electricity. When the resulting electricity is transmitted across thousands of kilometers by high tension grids, further 5-10% power is lost in the transmission. When the high tension power is stepped down through sub stations to lower voltage such as 100/200/400V further 5% power is lost. The net power received by a consumer is only 28% of the heat value of the fuel in the form of electricity. The balance 67% of heat along with Greenhouse gases from the combustion of coal is simply vented out into the atmosphere. It is the most inefficient method to generate power. Any environmental pollution is the direct result of inefficiency of the technology. Governments and EPA around the world ignore this fact .Thank to President Obama who finally introduced the pollution control bill for power plants after 212 years of industrial revolution.  Still this bill did not go far enough to control Carbon emission in its current form. Instead of arguing whether globe is warming due to emission of Carbon by human beings or not, Scientists should focus on improving the science and technology of power generation. For example, the electrical efficiency of a Fuel cell is more than 55% compared to conventional power generation and emits reduced or no carbon. Recent research by MIT shows that such conversion of heat into electricity can be achieved up to 90% compared to current levels of 35%.Had we developed such a technology earlier, probably we will not be discussing about GHG and global warming now. MIT research group is now focusing on developing new type of PV and according to their press release: “Thermal to electric energy conversion with thermophotovoltaics relies on radiation emitted by a hot body, which limits the power per unit area to that of a blackbody. Micro gap thermophotovoltaics take advantage of evanescent waves to obtain higher throughput, with the power per unit area limited by the internal blackbody, which is n2 higher. We propose that even higher power per unit area can be achieved by taking advantage of thermal fluctuations in the near-surface electric fields. For this, we require a converter that couples to dipoles on the hot side, transferring excitation to promote carriers on the cold side which can be used to drive an electrical load. We analyze the simplest implementation of the scheme, in which excitation transfer occurs between matched quantum dots. Next, we examine thermal to electric conversion with a glossy dielectric (aluminum oxide) hot-side surface layer. We show that the throughput power per unit active area can exceed the n2 blackbody limit with this kind of converter. With the use of small quantum dots, the scheme becomes very efficient theoretically, but will require advances in technology to fabricate.” Ref:J.Appl.Phys. 106,094315c(2009); http://dx.doi.org/10.1063/1.3257402 “Quantum-coupled single-electron thermal to electric conversion scheme”. Power generation and distribution using renewable energy sources and using Hydrogen as an alternative fuel is now emerging. Distributed energy systems may replace centralized power plants in the future due to frequent grid failures as we have seen recently in India. Most of the ‘black outs’ are caused  by grid failures due to cyclones, tornadoes and other weather related issues, and localized distribution system with combined heat and power offers a better alternative. For those who are skeptical about global warming caused by man-made greenhouse gases the question still remains, “What happened to billions of tons of Caron dioxide emitted into  the atmosphere by power plants and transportation  since industrial revolution?”.          

Can alternative energy combat global warming?

The world is debating on how to cut carbon emission and avert the disastrous consequences of global warming. But the emissions from fossil fuels continue unabated while the impact of global warming is being felt all over the world by changing weathers such as flood and draught. It is very clear that the current rate of carbon emission cannot be contained by merely promoting renewable energy at the current rate. Solar, wind, geothermal, ocean wave and OTEC (ocean thermal energy conversion) offer clean alternative energy but now their total combined percentage of energy generation   is only less than 20% of the total power generation. The rate of Carbon reduction by  renewable energy  do not match  the rate of Carbon emission increase by existing and newly built  fossil power generation and transportation, to keep up the current level of Carbon in the atmosphere. The crux of the problem is the rate of speed with which we can cut the Carbon emission in the stipulated time frame. It is unlikely to happen without active participation of industrialized countries such as US, China, India, Japan, EU and Australia by signing a legally binding agreement in reducing their Carbon emissions to an accepted level. However, they can cut their emissions by increasing the efficiency of their existing power generation and consumption by innovative means.

One potential method of carbon reduction is by substituting fossil fuels with biomass in power generation and transportation. By using this method the energy efficiency is increased from current level of 33% to 50-60% in power generation by using gasification technologies and using Hydrogen for transportation. The Fixed carbon in coal is about 70% while the Carbon content in a biomass is only 0.475 X B (B-mass of oven-dry biomass). For example, the moisture content of a dry wood is about 19%,which means the Carbon mass is only 38% in the biomass. To substitute fossil fuels, the world will need massive amounts of biomass. The current consumption of coal worldwide is 6.647 billion tons/yr  (Source:charts bin.com)and the world will need at least 13 billion tons/yr of biomass to substitute coal .The total biomass available in the world in the form of forest is 420 billion tons which means about 3% of the forest in the world will be required to substitute current level of coal consumption. This is based on the assumption that all bioenergy is based on gasification of wood mass. But in reality there are several other methods of bioenergy such as biogas, biofuels such as alcohol and bio-diesel from vegetable oils etc, which will complement biogasification to cut Carbon emission.

Another potential method is to capture and recover Carbon from existing fossil fuel power plants. The recovered Carbon dioxide has wider industrial applications such as industrial refrigeration and in chemical process industries such as Urea plant. Absorption of Carbon dioxide from flue gas using solvents such as MEA (mono ethanolamine) is a well established technology. The solvent MEA will dissolve Carbon dioxide from the flue gas and the absorbed carbon dioxide will be stripped in a distillation column to separate absorbed carbon dioxide and the solvent. The recovered solvent will be reused.

The carbon emission can be reduced by employing various combinations of methods such as anaerobic digestion of organic matters, generation of syngas by gasification of biomass, production of biofuels, along with other forms of renewable energy sources mentioned above. As I have discussed in my previous articles, Hydrogen is the main source of energy in all forms of Carbon based fuels and generating Hydrogen from water using renewable energy source is one of the most potential and expeditious option to reduce Carbon emission.

Liquid biomethane- an emerging fuel for rural economy.

Biogas is fast becoming a fuel of the choice for rural economy in many parts of the world because large number of agriculture and farming communities lives in rural area. Most of these countries depend on imported   Diesel, LPG and Gasoline for their industries, agriculture, transportation and cooking. Countries like India with large population spends a huge amount of foreign currency towards import of petroleum products, making it more vulnerable to the fluctuating oil and gas prices in the international market. However, there is an increasing awareness in India recently about the importance of generating biogas as an alternative energy source to fossil fuel because 70% of the Indian population lives in rural areas. With an estimated cattle population of 280 million (National Dairy development Board 2010) there is a potential to generate biogas at 19,500 Mw.

The following calculation is based on the costing details provided by successful case studies of community based Biogas plants in India. One community based biogas plant has 121 families consisting of 5 members per family as stake holders. They supply cow dung at the rate of 4.50 Mt/day for 365days in a year and generate biogas by an anaerobic digester, designed and constructed locally. Biogas is supplied to all the stakeholders every day for 2 hrs in the morning and for about 2 hrs in the evening for cooking. This is equal to burning 3025 kgs of wood/day (121 families x 5members/family x 5kg wood per member= 3025 x 4000 kcal/kg= 12.10 mil Kcal/day= 48.40 mmBtu/day).The piped natural gas in India is supplied now at the rate of $16/mm Btu, which means the plant is able to generate revenue worth $774.40 per day. But each family of 5 members are charged only Rs.150 per month or 121 families are charged 121 x Rs.150= Rs.18, 150/month ($363/month). The family members also supply milk to co-operative dairy farm which has also contributed to set up the biogas plant. Total cost of the project is $43,000 of which Government subsidy is $20,000, Dairy farm contribution $ 16,000 and the stake holders $7000.The economic and social benefit of this project is enormous. The economic benefit by way of fuel savings, revenue from the sale of vermin compose and by way of Carbon credit amounts to Rs.48,94,326 ($97,926/yr).(source:SUMUL).

The above case study clearly shows how successfully India can adopt bioenergy as an alternative to fossil fuel in rural areas. We have already seen how biogas can be enriched to increase its methane content and to remove other impurities by way of water scrubbing as shown in the figure. The purified and dried biogas with Methane content 97% and above can be liquefied using cryogenic process by chilling to -162C.The liquefaction of biogas is energy intensive but it is worth doing  in countries like India especially when there is no natural gas pipeline network.BLG (liquefied biogas)  is an ideal fuel for industries with CHP (combined heat and power) applications with energy efficiency exceeding 80% compared to conventional diesel engine efficiency at 30%.By installing LBG service station and catering to transport industry, India can cut their import of crude oil while reducing the greenhouse gas emissions.

Producing LBG also leads to a renewable fuel available for heavier vehicles. The fuel can be stored as LBG on the vehicle, which increase the driving distance per tank. The need is that the vehicle is running frequently, otherwise LBG will vaporize and CH4 will be vented to the atmosphere. LBG is in liquid form only when the gas is stored on the vehicle. When it gets to the engine it is in its gas phase. When LBG is delivered to remote fuel stations or storages it is transported in vacuum insulated pressure vessels. One such manufacture of these semi-trailers is Cryo AB and the dimensions of a standard equipped semi-trailer, suitable for Nordic logistic conditions, is shown in Figure 13.

This trailer is optimized for the transportation of LNG/LBG and has a tank capacity of 56,000 liters (~33,000 Nm3 LBG). It is vacuum insulated and the heat in-leakage is less than 0.9 % of maximum payload LBG per 24 hour. The maximum payload is 83.7 % filling rate at 0 bar (g) (=19,730 kg). The source of heat is the surrounding air and the heat in-leakage raises the pressure of the LBG. The maximum working pressure is 7.0 bar (g). If this pressure is exceeded gas is vented to the atmosphere through a safety valve. (Cryo AB, 2008)

Fuel station technology:

There are three different types of fuel station available, using LBG as a feed stock:

– LBG refueling station

– LCBG refueling station

– Multi-purpose refueling station

LBG stations fuel LBG to vehicles equipped with a cryogenic tank while LCBG stations refuel CBG. LCBG stands for liquid to compressed biogas and LBG is transformed to CBG at the refueling station. Multi-purpose refueling stations are able to fuel both LBG and CBG, and consist of one LBG part and one LCBG part. (Vanzetti Engineering, 2008a) There are a number of companies in the LNG business working with the development of fuel stations using LBG as a feedstock. The presented data in this text is based on information from three different companies; Cryostat, Nexgen fuels and Vanzetti Engineering.

This article will focus on the multi-purpose station and since the three companies’ designs are very similar, only a general description will be presented.

The reason why the multi-purpose station is chosen is because LBG could be a good alternative for heavier vehicles. Here it is assumed that these vehicles already are available and in use on a large extent. The refueling station assumes to be situated in conjunction with one of the frequent roads in India, not in vicinity with the gas network. The following requirements lie as a background for the design:

– Possibility to fuel both LBG and CBG

– One double dispenser for CBG; one nozzle for vehicles (NGV-1) and one nozzle for busses (NGV-2)

– One single nozzle for LBG

– Expected volume of sale: 3000 Nm3/day

– Pressure on CBG: up to 230 bar (200 bars at 15°C)

The standard equipment on the multi-purpose station consists of a storage tank for LBG, cryogenic pumps, ambient vaporizer, odorant injection system and dispensers. (Cryostat, 2008a)

There are three types of cryogenic pumps:

– Reciprocating

– Centrifugal

– Submerged

Reciprocating pumps are able to function at very high pressures and are used for the filling of buffer tanks and gas cylinders. Centrifugal pumps are able to produce high flow rates and are used for the transfer of cryogenic liquids between reservoir tanks or road tankers. (Cryostat, 2008b) A submerged pump is a centrifugal pump installed inside a vacuum insulated cryogenic tank. This tank is totally submerged in the cryogenic liquid, which makes it stay in permanently cold conditions. (Vanzetti Engineering, 2008b)

A sketch over a multi-purpose station can be seen in Figure 14. LBG is stored in a vacuum insulated cryogenic vessel and LBG is delivered with semi-trailers. The volume of the storage tank is usually designed to match refilling on a weekly basis. The transfer from trailer is either done by gravity or by transfer pumps, the latter significantly reducing transfer time. (Vanzetti Engineering, 2008a) From the LBG storage tank the station is divided into two; the LBG part and the LCBG part.

The LCBG part consists of a reciprocating pump, an ambient vaporizer and buffer storage. The reciprocating pump sucks LBG from the storage tank and raises the pressure to around 300 bars, before sending it to the ambient high pressure vaporizer. CBG is then odorized before going to the CBG storage and the dispenser. The buffer unit is gas vessel storage, with a maximum working pressure of 300 bar, enabling fast filling of vehicles. (Nexgen Fueling, 2008)

The LBG part only consists of a centrifugal pump that transfers LBG from the storage tank, through vacuum insulated lines, to the LBG dispenser that dispense LBG at a pressure of 5-8 bar. (Nexgen Fueling, 2008) Some LBG dispensers are supplied with a system for the recovery of the vehicle boil of gas. (Cryostar, 2008a) To reduce methane losses all venting lines are collected and sent back to the higher parts of the storage tank, to be reliquaries by the cold LBG. (Heisch, 2008) (Ref: Nina Johanssan, Lunds Universitet)

Economics of LBG: The LNG trucks averages about 2.8 miles per gallon of LNG, equating to about 4.7 miles per DEG. Table 5 compares the energy content, fuel economy and DEG fuel economy. The greenhouse emission is completely eliminated by using LBG.

Can Bio-gasification transform our world?

Carbon neutral biomass is becoming a potential alternative energy source for fossil fuels in our Carbon constrained economy. More and more waste –to-energy projects is implemented all over the world due to the availability of biomass on a larger scale; thanks to the increasing population and farming activities. New technological developments are taking place side by side to enhance the quality of Biogas for power generation. Distributed power generation using biogas is an ideal method for rural electrification especially, where grid power is unreliable or unavailable. Countries like India which is predominantly an agricultural country, requires steady power for irrigation as well as domestic power and fuel for her villages. Large quantity of biomass in the form of agriculture waste, animal wastes and domestic effluent from sewage treatment plants are readily available for generation of biogas. However, generation of biogas of specified quality is a critical factor in utilizing such large quantities of biomass. In fact, large quantity of biomass can be sensibly used for both power generations as well as for the production of value added chemicals, which are otherwise produced from fossil fuels, by simply integrating suitable technologies and methods depending upon the quantity and quality of biomass available at a specific location. Necessary technology is available to integrate biomass gasification plants with existing coal or oil based power plants as well as with chemical plants such as Methanol and Urea. By such integration, one can gradually change from fossil fuel economy to biofuel economy without incurring very large capital investments and infrastructural changes. For example, a coal or oil-fired power plant can be easily integrated with a large-scale biomass plant so that our dependency on coal or oil can be gradually eliminated.

Generation of biogas using anaerobic digestion is a common method. But this method generates biogas with 60% Methane content only, and it has to be enriched to more than 95% Methane content and free from Sulfur compounds, so that it can substitute piped natural gas with high calorific value or LPG (liquefied petroleum gas). Several methods of biogas purification are available but chemical-free methods such as pressurized water absorption or cryogenic separation or hollow fiber membrane separation are preferred choices.

The resulting purified biogas can be stored under pressure in tanks and supplied to each house through underground pipelines for heating and cooking. Small business and commercial establishments can generate their own power from this gas using spark-ignited reciprocating gas engines (lean burnt gas engines) or micro turbines or PAFCs (phosphoric acid fuel cells) and use the waste heat to air-condition their premises using absorption chillers. In tropical countries like India, such method of distributed power generation is absolutely necessary to eliminate blackouts and grid failures. By using this method, the rural population need not depend upon the state-owned grid supplies but generate their own power and generate their own gas, and need not depend on the supply of rationed LPG cylinders for cooking. If the volume of Bio-methane gas is large enough, then it can also be liquefied into a liquified bio-methane gas (LBG) similar to LNG and LPG. The volume of biomethane gas will be reduced by 600 times, on liquefaction. It can be distributed in small cryogenic cylinders and tanks just like a diesel fuel. The rural population can use this liquid bio-methane gas as a fuel for transportation like cars, trucks, buses, and farm equipment like tractors and even scooters and auto-rickshaws.

Alternatively, large-scale biomass can be converted into syngas by gasification methods so that resulting biomass can be used as a fuel as well as raw materials to manufacture various chemicals. By gasification methods, the biomass can be converted into a syngas (a mixture of Hydrogen and Carbon monoxide) and free from sulfur and other contaminants. Syngas can be directly used for power generation using engines and gas turbines.

Hydrogen rich syngas is a more value added product and serves not only as a fuel for power generation, but also for cooking, heating and cooling. A schematic flow diagram Fig 3,  Fig4 and Fig 6 (Ref: Mitsubishi Heavy Industries Review) shows how gasification of biomass to syngas can  compete with existing fossil fuels for various applications such as for power generation, as a raw material for various chemical synthesis and as a fuel for cooking, heating and cooling and finally as a liquid fuel for transportation. Bio-gasification has a potential to transform our fossil fuel dependant world into Carbon-free world and to help us to mitigate the global warming.

Hydrogen from seawater for Fuelcell

We have used Hydrocarbon as the source of fuel for our power generation and transportation since industrial revolution. It has resulted in increasing level of man-made Carbon into the atmosphere; and according to the scientists, the level of carbon has reached an unsustainable level and any further emission into the atmosphere will bring catastrophic consequences by way of climate change. We have already saw many natural disasters in a short of span of time. Though there is no direct link established between carbon level in the atmosphere and the global warming, there is certainly enough evidence towards increase in the frequency of natural disasters and increase in the global and ocean temeperatures.We have also seen that Hydrogen is a potential candidate as a source of future energy that can effectively substitute hydrocarbons such as Naphtha or Gasoline. However, hydrogen generation from water using electrolysis is energy intensive and the source of such energy can come only from a renewable source such as solar and wind. Another issue with electrolysis of water for Hydrogen generation is the quality of water used. The quality of water used for electrolysis is high, meeting ASTM Type I Deionized Water preferred, < 0.1 micro Siemen/cm (> 10 megOhm-cm).

A unique desalination technology has been developed by an Australian company to generate on site Hydrogen directly from seawater. In conventional seawater desalination technology using reverse osmosis process only 30-40% of fresh water is recovered as potable water with TDS less than 500 ppm as per WHO standard. The balance highly saline concentrate with TDS above 65,000 ppm is discharged back into the sea which is detrimental to the ocean’s marine life. More and more sweater desalination plants are set up all over the world to mitigate drinking water shortage. This conventional desalination is not only highly inefficient but also causes enormous damage to the marine environment.

The technology developed by the above company will be able to recover almost 75% of fresh water from seawater and also able to convert the concentrate into Caustic soda lye with Hydrogen and Chlorine as by-products by electrolysis. The discharge into the sea is drastically reduced to less than 20% with no toxic chemicals. This technology has a potential to revolutionize the salt and caustic soda industries in the future. Caustic soda is a key raw material for a number of chemical industries including PVC.Conventionally, Caustic soda plants all over the world depends on solar salt for their production of Caustic soda.Hydrogne and Chlorine are by-products.Chlrine is used for the production of PVC (poly vinyl chloride) and Hydrogen is used as a fuel.

In the newly developed technology, the seawater is not only purified from other contaminants such as Calcium, Magnesium and Sulfate ions present in the seawater but also concentrate the seawater almost to a saturation point so that it can be readily used to generate Hydrogen on site. The process is very efficient and commercially attractive because it can recover four valuable products namely, drinking water, Caustic soda lye, Chlorine and Hydrogen. The generated Hydrogen can be used directly in a Fuel cell to generate power to run the electrolysis. This process is very ideal for Caustic soda plants that are now located on seashore. This process can solve drinking water problems around the world because potable water becomes an industrial product. The concentrated seawater can also be converted in a salt by crystallization for food and pharmaceutical applications. There is a growing gap between supply and demand of salt production and most of the chemical industries are depending upon the salt from solar pans.

Another potential advantage with this technology is to use wind power to desalinate the water. Both wind power and Hydrogen will form a clean energy mix. It is a win situation for both water industry and the environment as well as for the salt and chemical industries. In conventional salt production, thousands of hectares of land are used to produce few hundred tons of low quality salt with a year-long production schedule. There is a mis match between the demand for salt by large Caustic soda plants and supply from primitive methods of solar production by solar evaporation contaminating cultivable lands.

The above case is an example of how clean energy technologies can change water, salt and chemical industries and also generate clean power economically, competing with centralized power plants fuelled with hydrocarbons. Innovative technologies can solve problems of water shortage, greenhouse gases, global warming, and environmental pollution not only economically but also environmental friendly way. Industries involved in seawater desalination, salt production, chemical industries such as Caustic soda, Soda ash and PVC interested to learn more on this new technology can write directly to this blog address for further information.

Fuelcell power using Biogas

Fuel cell technology is emerging as a base-load power generation technology as well as back-up power for intermittent renewable energy such as solar and wind, substituting conventional storage batteries. However, Fuelcell requires a Fuel in the form of Hydrogen of high purity. The advantage of Fuel cell is, its high electrical efficiency compared to conventional fossil fuel power generation technology, using Carnot cycle. Fuel cell is an electro-chemical device like a battery and generates power using electro-chemical redox reaction silently with no gaseous emission, unlike engines and turbines with combustion, rotary movements and gaseous emissions. The fuel Hydrogen can be generated using a renewable energy sources such as solar and wind as described in my previous articles, “Solar Hydrogen for cleaner future” dated 4 July 2012, and “Renewable Hydrogen for remote power supply “dated 28 June 2012.

Alternatively, Hydrogen can also be generated using biomass through Biogas. Biogas is an important source of renewable energy in the carbon constrained economy of today’s world. The biogas can be generated from waste water and agro-waste by anaerobic digestion using enzymes. Biomass such as wood waste can also be gasified to get syngas, a mixture of Hydrogen and Carbon dioxide. In anaerobic digestion, the main product will be methane gas accompanied by carbon dioxide and nitrogen while the main product in gasification will be Hydrogen, carbon monoxide and carbon dioxide and oxides of Nitrogen. Whatever may be the composition of the resulting gas mixture, our focus will be to separate methane or Hydrogen from the above mixture. In anaerobic digestion, the resulting Methane gas has to be steam reformed to get Hydrogen gas suitable for Fuel cell application. In gasification, the resulting Syngas has to be separated into pure Hydrogen and Carbon dioxide so that pure Hydrogen can be used as a fuel in Fuel cell applications. As I have outlined in many of my previous articles, Hydrogen was the only fuel we have used all these years and we are still using it  in the form of Hydrocarbons and it will continue to be the fuel in the future also. The only difference is future Hydrogen will be free from carbon.

We have to discuss two issues to mitigate Carbon emission, and it can be done by 1.Elimination of Carbon from the fuel source. 2. Generation of Renewable and Carbon free clean energy directly from solar and wind. One option  to cut Carbon from the fuel source is to use Biomass as the raw material to generate Hydrogen so that fresh Carbon will not be added  into the atmosphere by emissions .The second option is to generate pure Hydrogen from water by electrolysis using renewable energy such as wind and solar. Environmentally friendly waste-to-energy projects are becoming popular all over the world. But now most of these waste-to-energy projects generate either Biogas (Methane) by anaerobic digestion or Syngas (Hydrogen and Carbon dioxide) by gasification. Both these gases need further purification before they can be used as a fuel for power generation. The Methane content in the Biogas (about 60% methane and 40% Carbon dioxide with other impurities) needs to be enriched to 90% Methane and free from other impurities. The composition of a typical Biogas is shown in table1.

The resulting purified methane gas will be reformed using steam reformation in presence of a catalyst to get syngas; finally Hydrogen should be separated from resulting syngas so that it can be used directly into the Fuelcell.The common Fuel cell used for this application is invariably Phosphoric acid fuel cell.

PAFC uses 100% Phosphoric acid in Silicon carbide matrix as an electrolyte. PAFC is a self-contained unit completely enclosed in a cabin consisting of a gas reformer, Fuellcell power generator, Power conditioning unit and other auxiliaries. The PAFC is of modular construction with capacities ranging from 100Kw up to 500Kw as a single unit. It can be installed outdoor in the open and it can be readily connected to a piped Biogas. It can also be connected to existing piped natural gas or LPG bullet as a stand-by fuel. Any waste-to energy project can be integrated with Fuel cell power generation with CHP application to get greatest economic and environmental benefits. Hydrogen derived from biomass will be an important source of fuel in the future of clean energy; and Fuel cell will become an alternative power generation technology for both stationary power generation and transportation such as Fuel cell car or Hybrid cars.

PAFC is a compact, self-contained power generation unit that is used even for base load power. The electrical efficiency of PAFC  is about 42% .It is suitable for CHP applications so that the total energy efficiency can reach up to 85%.It is ideal for supplying continuous power 24×7 and also to use waste heat for space heating or space air-conditioning with an absorption chiller in CHP applications. The ideal candidates for PAFC power generation using CHP will be hospitals, super markets, Data centers, Universities or any continuous process industry.PAFC is now used as a backup power for large-scale renewable energy project with an access to piped natural gas. A schematic flow diagram of a fuel cell power generation is shown in Fig 3 using biogas at Yamagata sewage treatment plant in Japan. Biomass  based  Fuecell  power generation has a great potential all over the world irrespective of location and size of the country.