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 is stripped out of 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, the first element on the periodic table, consists of two atoms. 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. It is one of the most difficult substances there is to handle and contain. It is highly flammable and easy to ignite.

• It takes 50 kWh of electricity to put 1 kilogram (2.2 lbs.) of H₂ into a car and go 60 miles.
• It takes 50 kWh in a BEV (Battery Electric Vehicle) to power it for 180 miles.
• It takes 50 kWh of electricity to produces 20 kWh of usable H₂.
• 50 kWh of electricity is used every 2-3 days in the average home.

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 kWh of energy used to run them, only 3-4 kWh 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, solar, hydro and other renewable sources, to power the electrolyzers needed 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 renewable sources, or stored H2 fuel, to deliver electricity to the grid.

Hybrid renewable power plants can eliminate the need to build a new, complex and expensive H₂ distribution infrastructure, and deliver 3X more emission free miles to BEVs for the same amount of energy. It can provide local generation to rural communities making them more resilient.

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.

One tanker truck (25,700 kWh) is equivalent to:

• 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 a high pressure H2 tank, fuel cells, and lithium batteries. The fuel cell consumes hydrogen gas and (for the sake of this discussion) magically converts it to electricity. That electricity charges the lithium battery. The battery powers the electric drive motor. 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.

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.