The Hydrogen Car Folly

H₂ | Methane | Green H₂ | Power Plant | Distributing | Cars | Carbon

Hydrogen is a Distant Dirty Dream.

This essay should dissuade anyone from the fantasy of driving a hydrogen fueled car, or having a home hydrogen generator in their garage, in this lifetime.

The petroleum industry is pitching Blue, Gray, Black and Brown Hydrogen to many state governments as a clean energy replacement for gasoline. It is no more than a ploy to maintain and expand the production and sale of natural gas.

Today, 95% of Hydrogen gas is made from natural gas, aka Methane. The methane molecule, CH₄, consists of one carbon atom and four hydrogen atoms. Massive amounts of energy are required to split methane molecules into hydrogen and carbon, and the process is very inefficient. For every 10 kWh of energy used to produce H2, only 4 kWh usable energy are produced.

Hydrogen Gas (H₂)

Hydrogen gas consists of two atoms of hydrogen. It does not occur naturally in our environment. It is always attached to other atoms, most commonly oxygen, as in water (H₂0). Nothing is lighter than hydrogen gas. It is one of the most difficult substances there is to handle and contain. It is highly flammable, but less explosive than gasoline vapor.

• It takes 50 kWh of electricity to put 1 kilogram/2.2 lbs of H₂ into a car and go 60 miles.
• If we put the same 50 kWh into a BEV (Battery Electric Vehicle), it goes 180 miles.
• 50 kWh of electricity produces 20 kWh of usable H₂.
• The average home uses 50 kWh of electricity every 2-3 days.

Building a hydrogen infrastructure to match today’s gasoline supply will require decades and will be far more complex and expensive than upgrading the current electrical grid.

Methane, aka CH₄, aka Natural Gas

The current process used to make 95% of hydrogen gas is called Steam Methane Reforming (SMR). It is a mature industrial scale process that supplies several industries. The petroleum industry is proposing to scale SMR up to national fuel supply capacity. Hydrogen itself is not a greenhouse gas, but studies show that the energy intensive SMR process used to produce it generates 20% more CO₂ than burning natural gas.

Natural gas is another name for methane, a potent greenhouse gas. Methane (CH₄) is a molecule with one carbon atom and four hydrogen atoms. Using the SMR process, methane is split into hydrogen and carbon monoxide. The carbon monoxide and sulfur byproducts become a waste disposal issue. More greenhouse gas is generated from fossil fuel power plants generating power for SMR.

Green Hydrogen

Green hydrogen is viable for the future, but today it is generally experimental. Less than 5% of the world supply of H₂ is green. All the green H₂ in the world would power one city of one million people.

Green Hydrogen is made using renewable energy to power a process called “electrolysis”, which splits water (H₂O) into H₂ gas and oxygen. It is a simpler process and is done at much lower temperatures than SMR. Using renewable power eliminates much of the CO₂ from fossil fuel power plants. Electrolyzers are expensive and inefficient. For every 10 kW of energy used to run them, only 4 kW of energy is produced and stored.

Hybrid Renewable Power Plant

The best use of green hydrogen is in a hybrid renewable power plant which uses wind and/or solar to power electrolyzers to produce and store green hydrogen. The H₂ is stored on site in stationary high pressure tanks and fuel cells. A hybrid power plant can use wind, solar or H2 fueled generators to deliver electricity to the grid.

Hybrid renewable power plants will eliminate the need to build a new, complex and expensive H₂ distribution infrastructure, and deliver 3X more emission free miles to EVs for the same amount of energy.

Distributing 500 kilograms of Hydrogen Fuel

Hydrogen fuel is measured in kilograms, not gallons. One “tube tanker” truck can deliver up to 500 kilograms (1,100 lbs) of H₂ to a fueling station. H₂ cars average 60 miles (97 kilometers) per kilogram. Each truckload provides 30,000 miles (48,300 kilometers).

Producing 500 kg draws about 25,000 kWh from a power plant. Because H₂ is the lightest gas in existence, it must be compressed to 10,000 psi to put 500 kilograms into a tanker truck. For that the compressors draw another 700 kWh of energy per truckload.

This totals 25,700 kWh, and generates an average of 5,350 kilograms (2.5 tons) of CO₂ per truckload at the power plant. The H₂ is then transported over the highways in diesel fueled tube tankers, adding more energy and CO₂ to the process.

25,700 kWh will provide power for:

• 900 average homes for a day
• 30,000 miles (48,300 kilometers) in an H2 car.
• 96,000 miles (155,000 kilometers) in a BEV.

Types of Hydrogen Cars

FCEV – Fuel Cell Electric Vehicle

An FCEV is an EV that uses both fuel cells and lithium batteries. The fuel cell stores hydrogen gas and (for the sake of this discussion) magically converts it to electricity, which charges the lithium battery. The battery is necessary because a fuel cell is less capable of delivering instant high power the way a battery can. The fuel cell is charged to a relatively low pressure of 200-300 psi. Due to the low pressure in the fuel cell, very little H2 can be carried, resulting in a very short range.

H2ICE – Hydrogen Internal Combustion Engine

An H2ICE burns hydrogen gas much the same way a conventional petrol ICE does. Hydrogen burns at a higher temperature and requires high compression ratios. This makes converting a conventional gas engine somewhat impractical.

Tank Volume Rules Out H2ICE For Cars
A 28″(11 cm) diameter spherical tank (about the size of a dishwasher) is required to achieve a 200 mile range

A Rolling Bomb
To be fair, H₂ gas in the air is slightly less volatile than gasoline vapor. The bigger danger comes from the fact that to achieve a 200 mile range, the H2ICE fuel tank must be charged to a very high pressure of 10,000 psi. In the event of a fire, a very large explosion could occur. The complexity, cost, and danger of doing this make H2ICE a highly impractical approach.