Electric and green hydrogen vehicles

Electric Vehicles and Green Hydrogen, what are the efficiencies?

Both vehicles, electric and green hydrogen, are electric considering their engine. The difference is how the electrical energy gets to the engine and also how the processes for producing green hydrogen and batteries affect the costs and efficiency of these electric cars.

Estimated reading time: 7 minutes

Electric vehicles and green hydrogen, the differences

No battery electric vehicle (VEB) the engine is powered by the electrical charge that is stored in a large battery and usually lithium, which must be recharged using the mains. There are already many charging stations in Portugal, in the usual fueling places, on public roads and in car parks, which accelerates the sale of electric cars, which has already reached 40% in Portugal.

VEB battery electric vehicle; AFDC source
VEB battery electric vehicle; Source: AFDC, Alternative Fuels Data Center

Um car electric with hydrogen fuel cell (VECCH) produces its own electricity from a chemical reaction that takes place in the cell powered by hydrogen (H2).

Thus, the green hydrogen vehicles that are under development are in fact electric, as the engine that makes them move is electric.

Fuel cells or “Fuel Cell” have hydrogen which, when reacting with the oxygen in the air, results in electrons (electric flow) feeding the electric motor and the high voltage battery of the vehicle.

These batteries are smaller than those of electric cars and are used when starting the vehicle, as well as when power peaks are reached (Source: Hyundai). Consume about 1 kg of hydrogen per 100 km (Source: EDP) and the speed at which a hydrogen tank can be filled (about 5 to 6 kg) is similar to that required to fill a vehicle with a combustion engine. The autonomy of this hydrogen tank is therefore greater than that of electric batteries.

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The big problem is that public hydrogen refueling is virtually non-existent.

Hydrogen has already been used for several decades in the industrial sector, although it is produced from fossil fuels and is therefore called gray hydrogen. When it is produced from natural gas, in which the CO2 resulting from the process is retained and stored, it is called blue hydrogen.

Examples of the application of hydrogen in the chemical industry are the production of ammonia, essential for the manufacture of fertilizers, and the manufacture of steel in steel mills, one of the largest sources of pollution in the world.

VECCH hydrogen fuel cell electric vehicle; AFDC source
VECCH hydrogen fuel cell electric vehicle; Source: AFDC, Alternative Fuels Data Center

Most manufacturers bet on the development of electric vehicles - VEB, but there are two brands that stand out in VECCH, Toyota (with the Mirai) and Hyundai (with the Hyundai Nexo SUV).

Another way to decarbonize vehicles is to replace fossil fuels, diesel and gasoline, with synthetic fuels. However, an economical production of these fuels is not yet possible.

Investment, whether in new technologies or in the refinement of existing technologies, will bring the cost down and make them more attractive.

The production of green hydrogen differs from others by using renewable energies such as solar, wind or water and water as a fuel source. Research into the use of seawater is ongoing as water is, in many areas, a scarce resource.

In addition, the financial and fiscal incentives that governments see fit may help to find more sustainable and cost-effective solutions.

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Green hydrogen production process
Green hydrogen production process; Source: Earth Justice

Green hydrogen, in addition to the advantages of sustainability and energy independence, can be transported over long distances, be stored and partly be an alternative to natural gas.

The cost of charging hydrogen cells is very high compared to charging batteries. To a large extent this difference is related to the costs involved in transportation.

Process efficiency

The efficiency levels of the two technologies are still very different. Even considering green hydrogen, the only one that guarantees carbon neutrality as it is produced with renewable energies, it currently has a production cost of around €4,20/kg (Source: Ricardo Neves, ECO Newspaper).

In some studies, notably Automotive Industry 2035 – Forecasts for the Future, hydrogen is considered to be a good energy alternative, in particular for collective and long-distance transport, road, rail, sea and air. Production and storage costs will be critical, as well as the availability of the distribution network.

Hydrogen vehicles have advantages over electric vehicles in terms of vehicle weight, as they do not have large batteries and do not lose autonomy in colder climates.

O Hydrogen Council estimates that the demand for hydrogen will increase 14 times by 2050.

The maritime transport of Liquefied Natural Gas (LNG) currently faces several challenges for the transport of bulk liquid hydrogen (LH2). First of all, the very low boiling point of hydrogen (-252ºC) introduces complexity in transport safety. One of the safety problems is the so-called “boil-off”, that is, the release of hydrogen from the deposits with the consequent increase in temperature. These losses in hydrogen transport are much higher than in LNG. In addition, the energy needs to liquefy hydrogen are also much higher than the energy needed to liquefy natural gas.

Also, hydrogen has a much lower energy density than LNG, about 40% less. This will require an additional 2,5 LH2 ships to carry the equivalent energy carried on an LNG ship.

One of the latest discoveries comes from Australia, at Deakin University, where hydrogen was trapped in a boron nitride powder. If this process is viable on an industrial scale, it will allow storing and transporting hydrogen more easily, at ambient temperature and pressure. Later, to use it, just heat the powder to 200ºC for the hydrogen to be released.

Also, where possible, transport via pipelines will be more economical.

The current major disadvantage of green hydrogen technology is its low efficiency as well as high costs.

Efficiency of processes for the production of green hydrogen and electricity; Volkswagen font
Efficiency of processes for the production of green hydrogen and electricity; Volkswagen font

Thus, with battery electric vehicles, only 8% of the energy is lost during the transport logistics to the battery charging sites. When electrical energy is converted to the motor, an additional 18% of energy is lost. Therefore, the efficiency of this type of vehicle is around 70 to 80%, much higher than the efficiency of combustion engines, around 30% (Source: Volkswagen).

On the other hand, the waste in the production and logistics process of green hydrogen is very high, since in its production, from the electrolysis of water, 45% of the energy is lost.

A further 55% is lost inside the vehicle when hydrogen is converted into energy. This means that the overall efficiency of hydrogen vehicles (VECCH) is around 25% to 35% (Source: Volkswagen).

New technologies

Volkswagen, in partnership with Kraftwerk, has developed a new technology that allows the green hydrogen cell to have an autonomy of 2.000 km.

As mentioned, the fuel cell converts hydrogen into electricity using a cathode and an anode.

The hydrogen (H2) is routed through the anode and passes through an electrolytic membrane, which splits it into a proton and an electron. The electrolyte takes them through different paths, the electron goes through a circuit to create the electrical flow (electrons) that make the engine work and the protons pass through the cathode, where they unite with oxygen to produce water and release heat.

Operation green hydrogen electric car; Source AFDC Alternative Fuels Data Center
Operation green hydrogen electric car; Source AFDC, Alternative Fuels Data Center

In this process, innovation Volkswagen and Kraftwerk, translates into the use of a ceramic electrolytic membrane, instead of plastic, which is the material that has been used, making this process more economical.

Electric cars could either be powered by batteries or hydrogen. The future will tell!

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