Hydrogen Fuel Cell Vehicles

IntroductionGlobal warming has led to the rapid melting of glaciers, the rising of water levels worldwide and disappearing islands. The cause of these events can be attributed to human behavior in regard to the discovery, capture and distribution of energy. The recent crisis has led society to explore various renewable energy alternatives. Since the industrial revolution, society has been on a journey to manage energy. Manage because by the First Law of Thermodynamics: energy cannot be created or destroyed, it can only be interconverted into different forms. Public and private companies have been in a race to find the most sustainable, efficient, plentiful energy source; although most industry creating and changing innovations have happened in the last decade. However, an answer to our energy problem may not be one solution but a group of different energy sources that would be appropriate for each individual market. The world is not in an energy supply crisis, but instead an interconverting crisis. There is renewable energy all around us; we have just been interconverting fossil fuels into non-renewable by-products. Current research is focused to examine how to be able to interconvert and end up with renewable by-products. Fuel cell technology is just one of the more economical way to use energy while reducing the negative effects on our environment. Competitors to the fuel cell market include other renewable energy solutions. These include wind, solar, natural gas as well hybrid technology. Hybrid technology has been the most promising, however this innovation has only begun to enter the consumer marketplace in the last decade and has yet to achieve a zero emissions rating. Fuel cell technology can make this possible and therefore is the frontrunner to significantly reduce our overall CO2 emissions and our effect on the ozone. The purpose of this paper is to examine the technology as well as how to bring hydrogen fuel cells to the consumer marketplace in a profitable way and at a price point that would make this technology tangible for society.

Literature ReviewResearch in this topic first required a detailed study of the hydrogen fuel cell. This includes its major components, required input material and analysis of the chemical reactions that take place inside the fuel cell that allow the vehicle to use the released energy to propel the car into motion. Next, market participants were examined including hydrogen fuel cell manufacturers, leading automotive companies utilizing this technology, as well as hydrogen and platinum suppliers. After gathering the background science knowledge and combining it with analysis of the current market, competitors in the consumer fuel cell vehicle market were examined. With the base understanding of the science, suppliers, competitors and manufacturers of the industry, a careful analysis of the viability of this technology was done. Lastly, I concluded my research by looking at factors that may contribute to making hydrogen fuel cells a reliable renewable energy source of the next century. Hydrogen has many benefits over other sources such as oil or petroleum. Firstly it has a wide range of flammability, low ignition energy, high auto ignition temperature, is lightweight, and has high diffusivity. All these characteristics make hydrogen a great source of energy. Even our greatest inventions cannot be realized if they cannot be made to be economically viable. In 1838, Christian Friedrich Schonbein invented the idea or hypothesis of a fuel cell. Using this research Sir William Robert Grove actually developed the first fuel cell in 1839. (1) However since then and up until 1955, the technology was not applicable in the consumer marketplace. W. Thomas Grubb while at GE, in 1955, used sulphonate polystyrene ion-exchange membrane as an electrolyte. (2) All this innovation led to NASA using this technology in a well-known project called Project Gemini. This was the first commercial application of the fuel cell and since then all innovation regarding fuel cell has surpassed all other renewable energy sources. (3) To appreciate truly the applicability of the fuel cell, its composition must be examined. Hydrogen fuel cell technology is not a full-fledged answer to our energy problem however it may be the best innovation of our time regarding transportation. In order to appreciate the significance of the HFC we will first examine the science. This will allow us to see the limitations and advantages of this technology over other energy sources. We then will analyze all the players in this field: suppliers, sellers, buyers and most importantly for all renewable energy sources, the LCM, the limiting reagent distribution.The main source of todays hydrogen supply is natural gas. (4) The value of a fuel cell is dependent on the amount of power that can be extracted from it. Since the fuel cell supplies a fixed voltage, the more power that is drawn the more current is extracted which increases the loss of energy in the fuel cell. Most losses show up as voltages drops within the cell, thus it can be concluded that the voltage is directly proportional to the cells efficiency. If the energy is being used to propel an object, the output of the fuel cell has to be converted into mechanical energy, which leads to a further decrease in efficiency. There has been much innovation over the past decade, which has led to the emerging of new diagnostic techniques to help optimize cost and lifetime of fuel cell systems. Newer technology has been focused on the geometry of fuel cells and the capability of these cells to support various catalysts and changes that would result in reduced manufacturing cost, increase in durability and improved performance and better stability of catalysts. There is a necessity to arrange a block of cells, as one cell is not commercially viable. To generate a desired current cells have to be places into a series so current can flow and the power of the whole system is dependent on the weakest cell. Geometrical cell design of current cells is not capable of withstanding faults in the system. To reduce the effect of the weakest link cell, it has to be identified quickly. Professor Kucernak has been at work recently to solve this dilemma. (5)

Professor Kucernak has suggested that the design of fuel cells should be in a stack so that badly performing cells can be easily switched out, or temporarily removed so that the rest of the system can function. This type of system needs to be capable of showing which cell is problematic and the ability of the system to function near optimum conditions even with the bad cell in place. Optimistically it would be an even greater advantage to be able to access faulty electrodes and repair them easily. The purpose of Professor Kucernaks research has been on the mechanical design of fuel cells for optimum performance. The goal of the project is to integrate power control devices directly into the fuel cell, which would allow greater control of the cell compared to current designs. To produce a more efficient fuel cell, the research into new types of electrodes, in particular the production of through-membrane connectors. To install electrodes directly into the fuel cell stack completely changes the required design of the overall system. (5)

Current research also includes the study of alkaline conducting membranes, in detail to reduce costs of commercializing fuel cells. In direct methanol fuel cells, the problem is fuel crossing from anode to cathode without the production of energy was a major problem. This led to methanol being replaced with ethanol. Ethanol is much more commercially viable option as many companies are conducting research into extracting ethanol from plants. Any research leading to the decrease in cost of ethanol would be a boon to making fuel cells affordable. (6) Findings

In extremely simple terms it is a device that converts hydrogen-rich fuel and oxygen into an electric current with the help of an electrolyte, catalyst an anode and cathode. It captures the chemical energy expended during the reaction of hydrogen and oxygen. This differs from combustion engines in which the energy expended is thermal energy. Electricity is generated through the triggering of a reaction between fuel and an oxidant, in the presence of an electrolyte. After the reaction, water flows out of the cell while the electrolytes remain trapped inside the cell. (7)

The most common type of fuel cell is the PEM or Polymer Electrolyte Membrane variant. This membrane is a thin, solid, organic compound that has the consistency of plastic wrap and is as think as on average 5 sheets of printing paper. This membrane acts as the electrolyte, which can be defined as a substance that conducts charged ions but does not conduct electrons. This membrane must be kept wet to be able to allow particles to flow freely across it. The anode, negatively charged and porous to allow H to flow across it, is the point at which the loss of electrons occurs. This node has on it platinum particles along with carbon particles. The platinum is the catalyst that speeds up the rate of oxidation. The cathode is the place where the gain of electrons occurs. This point is positively charged. The cathode has the same characteristics as the anode with the exception of the fact that O flows through it. The reaction can be cyclic with the presence of hydrogen, hydrocarbons and oxidants. Fuel cells differ from electrochemical cell batteries in that fuel cells, an open system, consume reactants from an outside source and flow of these reactants has to be maintained. However, in batteries electrical energy is stored as chemicals in a closed system. (7) The amount of energy a fuel cell can produce depends on the type, cell size, size as well as operating temperature.Talking about fuel cells can lead to an extensive discussion, as there are many types. Close observation of the hydrogen fuel cell reveals that the oxidants used are Cl, O2 or CO2. However some other types of fuel cells use alcohols or hydrocarbons as fuel. Classification is determined by the fuel, oxidants, construction, anode and cathode materials and the type of electrolyte used. It is important to understand how various fuel cells function in order to better understand the fuel cell of real interest: the hydrogen fuel cell.

Fuel Cell TypeDescription

AFCWas used in the NASA lunar missions. Consumes hydrogen and pure oxygen

MCFC (molten carbonate)Used only in industrial and military applications. The operating range is such that non-precious metals can be used as catalysts bringing the costs down.

PEMAlso known as the Ballard fuel cell. Polymer Electrolyte membrane which is a proton exchange fuel cell. A solid polymer is used as an electrolyte and a porous carbon electrode, which contain platinum. Operate at 90 degrees Celsius and releases 90-degree heat as byproduct. Compared to combustion engines, which operate at 2,500 Celsius and give off 125-degree heat. This means PEM fuel cells can adapt to load changes quickly making it perfect for transport vehicles. (7)

PAFCElectrodes inside are mad of carbon paper coated with a thin coating of platinum catalyst. The system is not affected by the impurities in carbon monoxide in the hydrogen stream. Furthermore the use of platinum in this cell makes it very expensive to produce. (7)

SOFCHighly efficient, long-term stability, fuel flexibility, low emissions, low cost. Disadvantages include high operating temperature which can lead to long start up times and mechanical and compatibility issues

RFCRegenerative fuel cell or reverse fuel cells that run in reverse mode. It consumes electricity and chemical to produce another chemical.

The most energy efficient catalyst used is platinum but recent breakthroughs in technology has allowed the creation of a special core and shell nanoparticle that uses much less platinum than comparable fuel cells. This new cell performs much more efficiently and lasts a greater time than cells that use pure-platinum catalysts. The oxygen reduction reaction that happens at the cathode end creates H2O as waste. Platinum has long been used as the preferred catalyst however the oxidation-reduction reaction causes it to degrade gradually. The core-shell particle developed at Brown University reduces costs and decay of the expensive element. A 5-nanometer palladium core, which is surrounded by a layer of iron and platinum, was developed. The idea was that the molding in the shell would remain rigid thereby reducing the amount of platinum required to result in an energy efficient reaction. The development included decomposing iron pentacarbonyl and reduced platinum acetyl acetone, which results in a shell composed of only 30% platinum. In tests, the nanoparticles generated twelve times more current than available catalysts. The experiment was run over 10,000 cycles and still lasted 10 times longer than current platinum fuel cells, which begin to deteriorate after only 1,000 cycles. (8) The shells created varied from a width of 1 to three nanometers and it was discovered that 1-nanometer shells were the most efficient. It has been theorized by the scientist involved that the palladium core increases the catalytic capabilities of iron platinum, and that somehow the transfer of electrons between the core and shell metals has been observed. Metals that are chemically more active than palladium alone are being used to verify that the transfer of electrons in the particle. (8) Improving efficiency.Fuel cells in general release a great amount of heat. Separate cooling systems are needed to keep this heat under control. If the temperature exceeds the maximum, erosion of the catalyst plates can occur. This problem actually led to an innovation of a new high power cell with a heat generator. Heat released from these fuel cells could be used to heat water or generate steam. (9) Energy sources that utilize fossil fuels have significant upfront costs as well as ongoing costs, many of which are spread over time and may increase depending on the market conditions. In contrast renewable energy sources demand a high up-front cost but low maintenance costs, however the main cause of concern in the future of this technology is the efficiency capture and transport of hydrogen. The main problem with other renewable energy methods is that the sources of energy are not always available. For example, with wind turbines, it is not guaranteed that wind will flow at all times. Similarly, the sun is only available to half the world at a time at most disregarding cloud cover disturbances. Researchers at GE have stated that they have produced a prototype of a product that would lead to the ability to produce hydrogen for less than $3 per kilogram, compared to the current $8. Water is combined with potassium hydroxide electrolyte and forced past a stack of electrodes. The electricity causes water molecules to split into O2 and H gases. In actuality, hydrogen can be sourced more efficiently and at a lower financial cost than natural gas. (9) The main application of interest with regard to hydrogen fuel cells is in consumer vehicles. Honda first introduced the concept in 2006 and released as a 2008 model. However, it was only available in southern California where hydrogen stations were established. The vehicle could not be bought but only leased for $600 per month, however this also included unlimited hydrogen fuel. The FCX unfortunately was discontinued production this year. (11) Fuel estimations can be found in the following table: Table 1VehicleModel YearCombined Fuel (mi/kg)City(mi/kg)Highway(mi/kg)Range(mi)

Toyota Mirai201667--312

Honda FCX2014595860231

The cost of hydrogen fuel produced through steam formation which is the most cost effective way would be on average $4-$5 per kg. The Toyota Mirai was first introduced in November 2014, and is scheduled for release of 700 vehicles worldwide in the 3rd quarter of 2015. According to the EPA, fuel estimations can be found in Table 1. The price will be $57,000 and will only be available in California. The Mirai is different in that it uses fuel cell as well as hybrid technology. To date there are only 10 hydrogen-fueling stations in California, however the state government has approved $47 million for an additional 28 stations to be built. (10)

ConclusionFuel Cells Vehicles are limited by the unavailability as well as the cost ineffectiveness of platinum. Until a substitute catalyst is found FVCs will find it very difficult to be anything more than part of a niche market. It is incredibly difficult and inefficient to produce, store, transport and use hydrogen. Looking at the big picture, unless hydrogen fuel cell vehicles or other renewable energy source vehicles were to transport the hydrogen, combustion engine transport vehicles would still be required to meet the demand of massive distribution. Hydrogen should be treated as an energy storage mechanism, for example to store electricity, not a source of energy. Hydrogen gas is colorless, odorless and extremely flammable. This makes it an extremely dangerous source of fuel to be in a pressurized state in transport vehicles. Considering all these factors, hydrogen fuel cell vehicles look to be at least 20 years to be a significant part of the automotive market.

References

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