Vikram Sengupta explores the viability of hydrogen fuel cell cars as an alternative to gasoline and electric vehicles.
Do we really need alternative fuels for cars?
Both from the point of view of global warming and from that of the inevitable exhaustion of the Earth’s oil reserves, it has become highly desirable to develop an alternative energy source for automobiles. Petrol cars are practical, reliable, as well as tried and tested, yet with depleting fossil fuel resources — coupled with the environmental disadvantages of those fuels — they are no longer viable. One of the alternative fuels for cars is hydrogen, used in a fuel cell.
How does hydrogen power work?
A (Proton Exchange Membrane) hydrogen fuel cell is propelled by an on-board chemical reaction that combines hydrogen stored in the car with oxygen from the atmosphere. The reaction creates an electric current. This energy is used to power the car through electric motors. The byproduct is water, which is the only emission that the car produces . This means that it is a green, environmentally friendly solution.
Why not use electric cars?
The hydrogen fuel cell car seems like a win-win situation, because it essentially replaces the role of gasoline with hydrogen. This means that society does not need to change its basic ways to conform to a new technology — like with electric cars. One of my main issues with the electric cars of today is their charging time. While yes, the time to recharge the batteries on today’s electric cars is less than it used to be, it is still considerably longer than the average gasoline fill up. The benefit of the hydrogen fuel cell car is that the filling time is exactly the same as the gasoline cars everyone is used to. However, the hydrogen powered car has achieved almost no traction in the past few years from either the automotive industry or the government. Manufacturers and legislators seem eager on advancing the electric car; consumers have been convinced that it is the clean, environmentally friendly technology of the future, when — to me — it is almost as flawed as the current gasoline car.
Tesla Motors is notable for its successful push of its electrics cars into the mainstream. However, I am under the firm belief that Tesla and pure electric cars are popular because of their powerful marketing campaigns, and not because they are saving the planet. While it is true that electric cars are emission free vehicles, that does not mean that they are not harmful to the environment . A study in London by Engaged Tracking determined that,
“Tesla vehicles harm the planet just about as much as their diesel and petrol equivalents…Engaged Tracking determined that the production of Tesla vehicles — and generating the electricity to keep them running — contributes to greenhouse gas emissions just as much as traditional vehicles in the United Kingdom. This is because more CO2 is emitted during the manufacturing of electric vehicles, and the electricity Tesla vehicles in the U.K. require are generated mostly by coal and gas”.
How can we procure hydrogen?
There are numerous methods and none of them are easy to execute. One method is electrolysis , where a current is passed through the water and splits it into 2H+ and O2- ions. Hydrogen ions then move to the cathode, where a reduction reaction occurs to give the hydrogen ions enough electrons to bond, and form hydrogen gas. This process is very effective, but only when performed at high pressure and with an electrolyte to increase the conductivity of the water. Electrolysis is only completely renewable and green when the electricity is obtained from renewable sources.
A second method that one can use is called thermolysis . This is when steam is heated to 2000 C, the thermal decomposition point of water. The steam is then directly broken down into hydrogen and oxygen gas. This is however, very inefficient, and therefore not as widely used in industry. Another method is Natural Gas Reforming (or Gasification) . This consists of a synthesis gas — a mixture of hydrogen, carbon monoxide, and a small amount of carbon dioxide — created by stimulating a reaction of natural gas with high-temperature steam. At these high temperatures (700–1100 °C), and in the presence of a metal-based catalyst (e.g. nickel), steam reacts with methane to yield carbon monoxide and hydrogen. The carbon monoxide is then made to react with water to produce additional hydrogen. This method is the cheapest, most efficient, and most common. Steam reforming of natural gas is approximately 65–75% efficient. However, the use of carbon monoxide makes it dangerous, and overall the process is expensive. The use of natural gas is also a negative.
A new discovery unearthed that 20 km deep in the Earth’s crust, a layer of hydrogen-rich rock lies, where 1000 litres of hydrogen gas is stored per cubic metre . This vast and almost inexhaustible supply has its obvious benefits, but does pose some challenges. Let’s consider the depth for example, 20 km is much deeper than humans have ever dug before. The best effort came in the shape of the Kola superdeep borehole in Russia, which took 13 years to drill just 13.7 km, after which temperatures exceeded 180 C — more than the machinery could cope with . Drilling another 7 km would need major improvements in drilling technology. The other drawback is that the rock mined will need to be crushed to extract its hydrogen. This brings up the question of sustainability, as the process could become too inefficient to be conducted on a large scale. The other problem is that, although it is the richest vein of hydrogen ever found, it is not as dense as water. It is a lot easier to obtain from water, with over 1000 times more hydrogen per cubic metre than the rock. As a result, it is unlikely that this will be the main source of hydrogen, as it is simply too impractical. It seems that there are many different methods of procuring hydrogen, with no clear winner.
Where does that leave the hydrogen powered car?
The hydrogen powered car is a technology of the future, but it is not coming to fruition. Hydrogen cars are stuck in a chicken-and-egg situation of supply and demand. The cars are built in small numbers (4,293 units in 2017) and are extremely expensive to buy because there are no economies of scale , meaning only a select few will want to purchase this type of vehicle. As a result, there is a lack of hydrogen fuel cell cars on the road.
In addition, there are nowhere near enough hydrogen filling stations. This leads to a low demand for hydrogen, which means that little money is being invested into the new technologies. From the point of view of a filling station owner, adding hydrogen facilities is not economically viable and potentially too dangerous; this contributes to the low production numbers. The lack of ‘push’ from legislators further hinders the progress of the hydrogen fuel cell car.
As Fig. 2 shows, the promise of hydrogen fuel cell cars has not translated to reality. Their sales are barely a blip compared to the alternatives, and based on current information this is not likely to change in the foreseeable future. Therefore, even as societies are moving away from petrol and diesel powered cars, trends suggest that the electric vehicle is likely to supplant them, rather than hydrogen fuel cell cars.
The author of this article is Vikram Sengupta, an A-Level student with a keen interest in automotive technology, computer science, and natural language processing.
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