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Why Hydrogen Powered Vehicles Will Never Become Mainstream

By Connor McRae

It always surprises me when someone tells me that Hydrogen will be the next power source that powers the worlds next generation of cars. My own Grandfather even told me this a decade ago and had been thinking it would be the next big thing since the 1970s. With the electric revolution in full swing, I felt it is time to address the major issues Hydrogen has as an alternative energy source.

1. Storage and transportation is difficult

Most hydrogen used in the United States is produced very close to of within the site that it is used which is usually at large industrial sites. This is mainly due to difficulties in transporting hydrogen as it is not economically viable to supply hydrogen to a user that is any distance away. As a result of this, there is not yet an effective infrastructure for distributing hydrogen to the network of fuel stations required that would allow the use of hydrogen passenger vehicles to become a viable option.

Currently there are three main methods used in the transportation of hydrogen.

Pipeline – A pipeline is the most cost effective way to deliver large volumes of hydrogen but at the moment it is very limited as there is only about 700 miles of U.S. pipelines located near large petroleum refineries and chemical plants in Illinois, California, and the Gulf Coast. There is also quite a high initial cost of setting up a pipeline system and costs are increased further if the line has to go through or reach a point within a densely packed city. Existing gas pipelines cannot be used to transport hydrogen due to Hydrogen Embrittlement so the pipeline infrastructure has to be built from scratch.

In the UK there are currently no hydrogen capable pipelines although there have been proposals for them. The main issue with UK implementation is the high construction cost due to the densely packed towns and cities and the high labour costs.

High-Pressure Tube Trailers - Transporting compressed hydrogen gas by truck, railcar, ship, or barge in high-pressure tube trailers is expensive and used primarily for distances of 200 miles or less. This is the most cost effective method for supplying those with a low demand.

Liquefied Hydrogen Tankers - Cryogenic liquefaction enables hydrogen to be transported more efficiently over longer distances by truck, train or sea compared with using high-pressure tube trailers, even though the liquefaction process is expensive. This is because liquid hydrogen has 75% more energy content than compressed hydrogen gas at 700BAR. There is a drawback to this method as if the hydrogen is not used at a sufficiently high enough rate once delivered, it starts to oil off and evaporate. This fact requires that the hydrogen delivery and consumption rates are carefully matched.

EVs Do Not Have This Issue – Electric Vehicles already have a charging infrastructure and with 90% of charges carried out at home, there is not the huge demand for EV charging stations. The amount of cost involved in setting up electric infrastructure is miniscule compared with a Hydrogen fuel network.

2. Safety Issues

Hydrogen does have several properties that can cause safety issues to arise which would not have been an issue or at least as much of an issue as fossil fuel or electric engines.

Invisible flame – when Hydrogen burns it produces a colourless, tasteless and odourless flame that cannot be seen during daytime conditions. This could potentially be overcome in the same way they deal with methanol by adding a small percentage of another fuel (adding petrol to methanol). It is unknown whether this could be achieved but at this moment in time, there are no methods of colouring a hydrogen flame.

Odourless gas – Hydrogen, as a gas, is odourless so a leak in a fuel system or engine would be difficult to notice unless it was a large enough leak or under enough pressure to make a noise. This is also an issue with natural gas but for the use of natural gas in domestic settings, a minute amount of odorant is added to the gas so a leak can be smelt by humans.

Potential for leaking and accidental ignition – due to Hydrogen’s buoyancy, low viscosity and small molecular size, the potential for leakage is much higher than petrol and diesel. There is a higher chance of a fuel leak combusting due to the high rate of diffusion in air. The low ignition energy would imply there would only have to be a small amount of hydrogen in the air required for accidental combustion to occur (as low as 4 micrograms/s leak would suffice). Liquid Hydrogen has the same issue as a spillage can be ignited from a considerable distance due to the liquid evaporating into the surrounding air.

Extremely reactive with oxygen and other oxidizers – hydrogen has a small lower explosion limit (4% in air with 28% oxygen content) and a high upper explosive limit (75% in air with 28% oxygen content). This mean Hydrogen has the potential to explode at a large range of hydrogen/air mixtures so with the combination of the higher potential for fuel leaks, lack of maintenance or damage to the fuel system could prove catastrophic.

Does not support life – if a gas leak was severe enough in an enclosed environment, hydrogen has the potential to asphyxiate. Because hydrogen does not have any toxicity, in smaller doses, it does not have any negative health issues so if there was a leak in an open area, there would be no danger to life from a respiratory point of view.

Potential for leaking and accidental ignition – due to Hydrogen’s buoyancy, low viscosity and small molecular size, the potential for leakage is much higher than petrol and diesel. There is a higher chance of a fuel leak combusting due to the high rate of diffusion in air. The low ignition energy would imply there would only have to be a small amount of hydrogen in the air required for accidental combustion to occur (as low as 4 micrograms/s leak would suffice). Liquid Hydrogen has the same issue as a spillage can be ignited from a considerable distance due to the liquid evaporating into the surrounding air.

Liquid hydrogen has to be kept at very low temperatures – storing hydrogen as a liquid allows 75% more energy content than gas stored at 700BAR so it is more economical in certain circumstances to store/transport hydrogen as a liquid. The issue is that it has to be stored at −252.87°C so handling requires protective equipment in order to avoid freeze burns. This is another issue that could arise if there is a spillage.

3. Hydrogen is nowhere near as efficient as EVs

There are currently two ways commonly used to create Hydrogen.

Electrolysis - The first major issue is that, due to the laws of thermodynamics, the electrolysis process will never be 100% efficient which is already generating an extra step between producing electricity and the wheels spinning. It would make more sense just to charge a battery in the first place. The process also requires a lot of electricity which, although can be sourced from renewable sources, the majority of the worlds power grids are still using fossil fuels. The brings up the old complaint from the oil hold outs that you are simply moving the exhaust pipe from the back of your car to the power station your electricity comes from.

Natural Gas – The most popular way to produce Hydrogen in the US is Natural Gas Reforming. This process is between 65% and 75% efficient but still relies on Hydrocarbons for production. 95% of the Hydrogen produced in the US is a result of this process. Although it is less destructive to the environment than using oil, it is still not as green as using renewable electricity.

Fuel Cells and HICE – The current favoured method of Hydrogen propulsion are fuel cells which are generally between 40% and 60% efficient which is very poor considering that the drivetrains in EVs are much closer to 100%. You can choose to use a Hydrogen internal combustion engine but they have even lower efficiency levels than conventional oil based engines. You also have to factor in that if you chose to run an engine on Hydrogen, a whole new engine would have to be developed for the different compression ratios compared to fossil fuels. An existing engine can be modified but it requires a lot of additional parts such as Non-platinum/nickel spark plugs, Gas fuel injectors, High pressure fuel pump, Stronger head gasket, Custom intake manifold and strengthened crankshaft, Higher temperature engine oil and upgraded cooling system, High pressure fuel and an ECU re-map or custom engine management. Hydrogen also causes ferrous metals to become brittle so any components of an engine that are in contact with the fuel would need to be changed.

4. They Are Expensive

A hydrogen vehicle is still more expensive than buying an electric vehicle by a considerable margin. Toyota have released their new Mirai and the retail price is almost $60,000 USD. You could buy an equivalent EV for half that money and with a Mirai, you still have to pay for fuel that is pretty much the same price as petrol. It just makes no sense.

Would you buy a small family hatchback for $60,000.

5. Hydrogen’s Only Advantage Over EVs Doesn’t Exist.

The only real advantage of Hydrogen over EVs is that they do not need to be charged so they theoretically have no range issues. In practice, this is not the case. When is the last time you have seen a Hydrogen refueling station? If you actually wanted to travel anywhere in a Hydrogen vehicle, you will seriously struggle to find somewhere to refuel. Also with the lack of investment going into developing Hydrogen vehicles compared to EVs, it is highly unlikely that Hydrogen fuel stations are going to start popping up everywhere.

Ultimately, there is no logical reason to buy a new Hydrogen vehicle and the chances of that changing are slim at best. With the availability of EVs becoming better and more financially accessible, there is only one real choice when it comes to alternative energy vehicles.

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