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Category Archives: PEM Electrolyzer

There is a general opinion that Hydrogen is now very expensive compared to Gasoline and Diesel. It depends on how you generate Hydrogen. We have used Gasoline and Diesel for several decades and real cost of crude oil is much lower than what we are paying for Gasoline and diesel at the service stations. Crude oil is formed naturally and all the cost involved is for pumping, transportation and refining. The cost of energy spent on transportation and refining is also comparatively low. It is the geopolitical situation in the world, supply demand gap, Government taxes and levies, inventory levels, financial market and distributors play a key role in fixing the price of these fuels.

Hydrogen can be generated from tap water without involving fossil fuels at all. But Governments are spending on research and development of Hydrogen generation using fossil fuels such as natural gas and coal. It is understandable that these sources are suitable for bulk production of Hydrogen on an industrial scale. We will also be able to use existing fossil fuel infrastructure to the most extent. But the flip side of this approach is Hydrogen generated by this route is still not pure enough to meet Fuel cell requirements. This Hydrogen may be suitable for Hydrogen combustion engines. Why they are not suitable? For example, Hydrogen is generated from natural gas by steam reforming,Syngas is generated as an intermediary product which is a mixture of Hydrogen and Carbon monoxide; but also other impurities present in natural gas such Sulfur,Phosphorus and Mercaptans etc.Natural gas has to be purified to remove all these impurities before it can be subject to steam reformation. In spite of an elaborate purification methods adopted, Fuel cell suppliers are reluctant to guarantee the life of their Fuelcell.The Fuel cell uses expensive Platinum as a catalyst which can be readily poisoned by the presence of impurities in Hydrogen, produced from natural gas. This is one of the main reasons why Hydrogen becomes expensive by this route. Industries can pay high cost for this Hydrogen, but ordinary citizens cannot afford to pay.

Hydrogen can be generated directly from tap water by simply electrolyzing it using a Direct current such as solar and wind. If we use grid power, it requires about 68kwhrs of electricity, costing about $3.40 per Kg of Hydrogen. Assuming Hydrogen will cost about $5 per kg after compression and storage, it is still worth the cost. This Hydrogen will give a mileage of 73.4 miles/kg using Fuel cell car. This is equal to 3.67 Gallons of gasoline costing about $13.76, at the rate of $3.75 per gallon. It is very clear that hydrogen is cheaper than gasoline or diesel. At the current price,Gasoline  costs 275% more than Hydrogen gas.

By converting existing coal and oil based power plants into IGCC, Integrated Gasification and Combined Cycle plants, Government can cut the current emission levels of greenhouse gases, and at the same time supply electricity at the prevailing rates. We do not have to import oil or gas. Government should fund conversion of coal and oil-fired power plants into IGCC plants and create Hydrogen infrastructure, by producing more Hydrogen Fuel cell cars and Hydrogen service stations. By adopting this policy, US Government can bring down the prices of crude oil in the international market which will help cut the prices of all other petrochemical products like fertilizers, plastics, drugs and cosmetics. The crux of the issue is to divert petroleum products from fuel use to other uses. At the same time Governments can reduce their greenhouse emissions to the level demanded by scientists. By reducing the cost of solar panels to less than $.100 per watt, Renewable Hydrogen will become a commercial reality and that will be the end of fossil fuels.

In a Regenerative fuel cell the results of redox reaction between Hydrogen and Oxygen, are power and water; the above reaction can be reversed in the same electrochemical process to regenerate hydrogen and oxygen. Such a system is called ‘regenerative fuel cell’. It is a perfect example of a closed circuit system. In ancient Hindu mythology there were citations that claim water came from fire and fire came from water. Two gaseous elements Hydrogen and oxygen reacts violently rather explosively resulting in cool water. Perhaps Hindu mythology terms this reaction as fire which results in water. Similarly by passing a direct current into water, it splits water into oxygen and regenerates Hydrogen, which is a symbolic representation of Fire. Many would have watched a number of ‘you tube videos footings’ on water gas. The water gas or Brown’s gas is a mixture of Hydrogen and oxygen along with un-dissociated water molecules liberated during the process of electrolysis. It can be lit into a flame similar to Oxy-acetylene flame and can be used even to cut metal plates. That is the power of brown’s gas, which I call Oxy-Hydrogen gas. This torch is commercially marketed for metal cuttings applications. But production of pure Hydrogen completely free from Oxygen is a matter of great commercial importance.

Hydrogen is one of the lightest gases and it has a strong bondage with noble metals like Platinum and Palladium. Platinum  catalyst with carbon as a carrier has a wider industrial applications such as hydrogenation in fine chemicals and pharmaceuticals. The author has experience in such applications in bulk drug manufacturing such as Ephedrine and Paracetamol. In a PEM (Proton exchange membrane fuel cell) MEA (membrane electrode assembly) is the heart. The Platinum catalyst coated on the surface of the ‘Nafion’ membrane reacts with gaseous Hydrogen gas. It strips the electron from hydrogen atom while the polymer membrane allows only proton to pass through. The expelled electron flows around the circuit. Flow of electron is nothing but current or electricity. The proton crosses the membrane and reacts with incoming Oxygen through cathode forming water. It is an exothermic reaction and generates heat similar to any combustion reaction, that has to be dissipated.In larger installation we can use this waste heat for a typical CHP (combined heat and power applications) such as power and steam or chilled water or for space cooling. Fuel cell (based on Hydrogen fuel) operates quietly with absolutely no emission except water, and of course, there is no smoke. It is an ideal power source for 24×7 applications such as hospitals, call centers, departmental stores and continues process industries.

In the reverse process of a Fuel cell, the electrochemical device becomes an Electrolyzer splitting water into Hydrogen and oxygen. The electrolyzer works the same way as Fuel cell except in reverse direction; feed is de-ionized water and the products are Hydrogen and Oxygen. In bipolar alkaline electrolyzer, a catalyst such as potash lye is added where in solid polymer electrolyzers platinum acts as a catalyst like a Fuelcell. The generated Hydrogen comes under pressure obviating the use of an extra compressor. The Hydrogen is stored in cylinders for further usage.

As I mentioned in my previous articles the power required to split water into Hydrogen and Oxygen is more than the power generated from the resulting Hydrogen by a Fuelcell.That means an input of excess energy is necessary for a regenerative fuel cell to run successfully .Where this energy will come from depends on the cost benefit analysis to be made. Surplus Hydro power is ideal for such regenerative fuel cell applications. But we can also use various other renewable energy sources such as wind, solar, geothermal, OTEC depending upon the site and applications. The biggest advantage with regenerative fuel cell is there is no other input except the excess power to be supplied. When renewable energy is deployed on large commercial scales then regenerative fuel cell will become a clean solution of the future. I have no doubt in my mind that this will become a commercial reality. Of course the top policy makers should understand the potential and make a right decision and encourage more business and industries to deploy such systems. The energy costing model cannot be based on fossil fuel model because fossil fuel is not renewable. This is the crux of the problem.

In our future articles we will present case studies of various clean energy systems that are already in commercial operation. I also welcome articles from clean energy professionals with life project experience and problems they face. I welcome comments and feedback from business, industries and people.

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