»Battery electric« vs »hydrogen fuel cells«

»Battery electric« vs »hydrogen fuel cells«

Battery electric vehicles (BEVs) have been in one or another form present since 1851 and hydrogen fuel cells technology was invented in 1839. Hydrogen has been in a way already used as a fuel in 1970es. Attempts of hydrogen use for powering cars are noted even before stated date. Still the fossil fuel industry has been dominating the mobility for about 160 years.

In 2019, by IEA, there were 7.2 million battery electric cars on the road worldwide. World economic forum has in January 2021 reported that globally, battery electric car sales reached 2.3 million in 2020. The number of hydrogen vehicles on the road is significantly less, 25,210 in 2019, according to IEA.

One of the upsides of BEVs is that the infrastructure of electric network is already existing. It has been much easier to set up charging stations for charging electric vehicles connecting them to the grid, then to establish hydrogen fulling stations. BEVs can be charged at home and the cost of electicity is in comparisson to hydrogen about 8 times cheaper.

The upside of the hydrogen is a high specific energy (aka energy per unit mass), which presents an ideal potential fuel for powering heavy vehicles, such as planes, boats, trucks and similar. For hydrogen cars the costs are too high to reach the demand that would initiate higher scale of offer. This might be changing in the future and even near future since some markets like for instance Japan have made a political decission to invest into extensive expansion of hydrogen mobility. Hydrogen cars are also well known in California, USA. In most countries the fulling stations for hydrogen are scarce and in the begining of 2021 they are about 3 models of hydrogen cars in the market, one from Toyota and another two from Hyundai.

Hydrogen gas can be produced from natural gas, by steam methane reforming reaction, which also has carbon monoxide and carbon dioxide as a by-product. This process consumes more energy than is obtained. For example, coal is quite ideal for energy production, for one unit of energy consumed, 80 units of energy are obtained. It is far the least appealing for the production of hydrogen and electricity, because its harmful emissions. In comparisson, for production of bio-diezel one invested energy unit produces 1.3 units of energy. They are several other ways to produce hydrogen, like biological water splitting, fermentation, conversion of biomass waste, photoelectrochemical water splitting, solar thermal water splitting and renewable electrolysis. They all have issues to be overcame in order for the hydrogen to reach scale of use. In comparisson to electricity production to charge the ion-lithium electric batteries »hydrogene falls behind when considering end to end production« (Skillshare,2018). The renewable electrolysis, a popular way of hydrogene production, cunsumes more energy than steam methane reforming reaction. The loss of original energy produced by renewable sources of energy put into the process is 30%. The energy efficiency of hydrogene produced by electrolysis is then 70%. With polymer exchange membrane electrolysis method the energy efficiency of hydrogene is 80% and it can be produced on site. In comparisson the battery charging efficiency is 99%. On site production costs can be higher due to the lower volumes of production.

The production cost difference does not explain the final cost difference of both power sources. The next loss in efficiency of hydrogene and additional cost hides in transport and storage of pure hydrogene. To store the hydrogene as gas the cost is additional 13% of energy loss, liquifyling hydrogen loses 40% of initial energy, including the weight of refrigirators and refrigeration itself. However, if the production of hydrogene is made off site the transport costs, transport emissions and energy loss needs to be calculated in the price of hydrogene. The distribution of hydrogene through pipelines results in 10% up to 40% of energy loss. However, losses are also made in electicity distribution through the grid from 5% up to 30%. To sum up, the losses for hydrogene can in total, depending on different factors, be up to 56% while for the electric energy produced by renewable resources and distributed to the grid they can amount to 30%.

Tank to wheel conversion efficiency means for hydrogene that the hydrogen once in the tank must be re-converted into electricity. The process with pure hydrogene uses additional 40% of energy, resulting in 60% energy efficiency from a tank. The losses of energy are also when charging batteries and due to leakage of batteries, this may amount to around 30% of energy losses. However, the conversion from AC current to DC current represents losses also for hydrogene in terms to DC current from fuel cells being converted to AC current powering the motor. Fuel cells and electic motor efficiency is around 90-95%.

Additionally to the above two points need to be taken into account as well: the cost of production for both types of vehicles and which of both choices can make better sales.

The bottom line is that both technologies are or can be greener than internal conbustion engines. Fuel cells technology provides shorter fulling times and longer authonomy of vehicles on one charge in comparisson to majority of electic cars in 2021. Most importantly hydrogen answers to some technical problems battery technology has when addressing alternative fuels in the segment of heavy vehicles. The batteries for BEVs are faced by other challenges: the lifecycle, reduced efficiency due to fast charging, recycling, expensive and somewhat limited resources, materials of the components, battery storage of electric energy produced by RES and more. Still the production of electric energy from RES and the BEVs are currently the cheaper options. Beside this the infrastructure is already set up for BEVs. If politicians want that hydrogen vehicles reach the comparable levels of economy of scale as the BEVs, more investments need to be made in the research to tackle the above mentioned issues, infrastructure set up and production of vehicles.

Sources:

Arso, 2012: Energy losses in conversion and transmission. Found on:  http://kazalci.arso.gov.si/sl/content/izgube-energije-v-pretvorbi-prenosu-1, 2021.

World Economic Forum, 2021: 2020 was a breakthrough year for electric vehicles. Here’s why. Found on: https://www.weforum.org/agenda/2021/01/electric-vehicles-breakthrough-tesla-china/, 2021

IEA, 2020: Global EV outlook 2020. Found on: https://www.iea.org/reports/global-ev-outlook-2020, 2021

NREL, 2021: Hydrogen Production and Delivery. Found on: https://www.nrel.gov/hydrogen/hydrogen-production-delivery.html, 2021

Skillshare,  2018: The Truth about Hydrogen. Found on: https://www.youtube.com/watch?v=f7MzFfuNOtY, 2021.

Two Bit Da Vinci, 2018: Why Battery Electric Cars are Dominating Hydrogen Fuel Cell Cars. Found on: https://www.youtube.com/watch?v=k7JRIUPhSJE, 2021

Wikipedia, 2021: William Robert Grove. Found on: https://en.wikipedia.org/wiki/William_Robert_Grove, 2021

Wikipedia, 2021: François Isaac de Rivaz. Found on: https://en.wikipedia.org/wiki/Fran%C3%A7ois_Isaac_de_Rivaz, 2021

Addy Majewski, 2021. »Fossil Fuels and Future Mobility«, DieselNet. Found on: https://dieselnet.com/tech/energy_mobility.php, 2021.

Hyundai Motor UK, 2018: All-new Nexo. Found on: https://www.hyundai.co.uk/new-cars/nexo, 2021.