[NEWS] BSC: Battery electric vs hydrogen fuel cells

Part 2

Battery electric vs hydrogen fuel cells: the relevance of hydrogen and details related to his production and usage

Source of the image: www.toyota.com/mirai/ 

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%.