Fuel Cell Electric Vehicles use hydrogen gas as a fuel. The hydrogen passes through the fuel cell, and is combined with oxygen to produce an electric current.
On board the vehicle, hydrogen is stored in a compressed form: 350bar for heavy-duty vehicles and 700bar for cars. If an accident occurs, the tanks are designed to release hydrogen safely. Since hydrogen is so light, it quickly rises up into the atmosphere (at around 20m/s), posing no risk. Furthermore, pure hydrogen is not flammable, as it needs oxygen for the reaction to occur, making it safe to store.
Fuelling is done in much the same way as gasoline. The user goes to a hydrogen dispenser and connects a nozzle to a receptacle on the car. Refuelling takes between 3 and 5 minutes using a strict protocol (SAE J2601) that guarantees optimal fuelling times.
Hydrogen for cooking
Just like natural gas, hydrogen can burn and therefore be used for cooking. Catalytic burners also exist and serve the same purpose.
In countries where the electric grid is well developed, this has less of an impact, as people can simply use an electric hob. But for developing countries, and poor households, having access to a clean source of fuel instead of firewood could prove to be lifechanging.
Indeed, burning wood in closed spaces poses a threat due to harmful carbon emissions, such as PAH (Polycyclic Aromatic Hydrocarbon), which can cause cancer, cardiovascular disease and poor fetal development. Instead, a single hydrogen station could provide enough hydrogen, every day, for hundreds of household, drastically improving their quality of life.
As the world turns more and more towards renewable sources of energy such as wind, solar or hydro, the global energy supply becomes more unpredictable, while the demand stays stable.
It becomes attractive to use surplus electricity to produce hydrogen and effectively store energy. The hydrogen can then be used to power fuel cells when the energy supply is low, thus normalising effective power supply.
This has several benefits, mainly: maximising the "usefulness" of renewable energy installations, decreasing the load on existing fossil fuel infrastructure or decreasing energy price during on peak demand.
Natural Gas Enhancement
Natural gas used for heating and cooking can be enhanced with hydrogen by up to 20%, without any change to the existing infrastructure. This reduces the amount of methane used for the same heating value, ultimately reducing carbon emissions..
By producing hydrogen from renewable sources, you can effectively reduce the carbon footprint of household heating and cooking, easing the transition to a zero carbon economy.
A trial was conducted at Keele University in a project known as HyDeploy. Staff in the university canteen say that the 20% hydrogen has made no difference to their cooking regime. "If a 20% blend were to be rolled out across Britain, it would reduce CO2 emissions by 6 million tonnes - equivalent to taking 2.5 million cars off the road" (Source: BBC)
By-products: Water and Oxygen
To avoid degradation of the PEM (Proton Exchange Membrane) electrolyser stack , water must first be purified. At RHizome2, we have a provision to increase the size of the water purification system, which will produce excess water that can be distributed to the local community. This can prove especially useful in developing countries, by providing access to clean, drinkable water.
The second by-product is oxygen. 55% of commercially produced oxygen is consumed by the steel industry, 25% by the chemical industry and the remaining 20% in other applications, such as medical, metal cutting and welding, oxidizer in rocket fuel, etc...
It becomes very attractive to keep the oxygen produced, instead of venting it. Even more so when we know that for each kg of hydrogen, 8kg of oxygen is produced.
The global ammonia market was worth 50 billion $ in 2016, and green hydrogen will play an important part in reducing its carbon footprint.
Ammonia is a chemical, mostly used as a fertiliser, and it has a worldwide impact on food production. It is produced vis the Haber-Bosch process, by combining hydrogen and nitrogen extracted from air, to ammonia.
Currently, 80% of the ammonia produced is used for fertilising crops. The hydrogen consumed for ammonia synthesis comes from steam methane reforming, which releases vast amounts of CO2 in the air. By sourcing hydrogen from water, using electrolysis, it is possible to drastically reduce carbon emissions in the agricultural sector.
Ammonia is also an efficient way of transporting hydrogen over vast distances, especially tankers, as it has a much higher hydrogen content than liquid hydrogen.
Methanation is a chemical reaction that converts carbon dioxide and hydrogen to methane and water.
By capturing carbon dioxide in the air and releasing it when burning the methane, overall carbon emissions don't increase. You're essentially recycling carbon dioxide that's already there, in the atmosphere.
It is advantageous to produce methane as there is already an existing market for methane used as a fuel. It is also attractive to store energy in the form of methane, as methane storage is 10 times cheaper than storage of hydrogen (Source: Utrecht University Faculty of Science)