Like all-electric vehicles, fuel cell electric vehicles (FCEVs) use electricity to power an electric motor. In contrast to other electric vehicles, FCEVs produce electricity using a fuel cell powered by hydrogen, rather than drawing electricity from only a battery. During the vehicle design process, the vehicle manufacturer defines the power of the vehicle by the size of the electric motor(s) that receives electric power from the appropriately sized fuel cell and battery combination.
Hydrogen fuel cells generate electricity using a chemical reaction. Each fuel cell has two electrodes; a negative anode and a positive cathode. The reaction to produce the electricity happens at these electrodes, with an electrolyte carrying electrically charged particles between them and a catalyst to speed up the reactions.
Hydrogen acts as the basic fuel in a hydrogen fuel cell, but the cell also needs oxygen to work. One of the largest advantages of these fuel cells is that they generate electricity with very little pollution, as the hydrogen and oxygen used to generate the electricity combines to produce water as a by-product. Cells that use pure hydrogen as fuel are completely carbon-free.
Other types of fuel cell system include those that use hydrocarbon fuels like natural gas, biogas, or methanol. Because fuel cells use an electrochemical reaction rather than combustion, they can achieve higher efficiencies than with traditional energy production methods. This can be improved further by with combined heat and power generators that use waste heat from the cell for heating or cooling applications.
The process by which a fuel cell works can be summarised as follows:
Single fuel cells do not generate a large amount of electricity, so they are arranged into stacks to create enough power for their intended purpose, whether that is powering a small digital device or a power plant.
Fuel cells work like batteries but, unlike batteries, they will not run down or need recharging and can continue to produce electricity while the fuel source (in this case, hydrogen) is supplied.
Being comprised of an anode, cathode and an electrolyte membrane, there are no moving parts in a fuel cell, making them silent in operation and highly reliable.
Hydrogen fuel cell technology presents several advantages over other power sources , including:
Hydrogen is the most abundant element in the Universe and despite the challenges associated with its extraction from water, is a uniquely abundant and renewable source of energy,perfect for our future zero-carbon needs for combined heat and power supplies.
Hydrogen fuel cells provide an inherently clean source of energy, with no adverse environmental impact during operation as the byproducts are simply heat and water. Unlike biofuel or hydropower, hydrogen doesn’t require large areas of land to produce. In fact, NASA have even been working on using hydrogen as a resource with the water produced as a byproduct being used as drinking water for astronauts. This shows that hydrogen fuel cells are a non-toxic fuel source and therefore superior in this way to coal, natural gas and nuclear power which are all either potentially dangerous or hard to obtain. Production, storage and use of hydrogen will play an important role in driving further development of renewable energy, by balancing their intermittent supply modalities with the challenging end-user demands, avoiding the need for significant early investment to upgrade grid infrastructure.
Hydrogen fuel cell technology provides a high-density source of energy with good energy efficiency. Hydrogen has the highest energy content of any common fuel by weight. High pressure gaseous and liquid hydrogen have around three times the gravimetric energy density (around 120MJ/kg) of diesel and LNG and a similar volumetric energy density to natural gas. These
Hydrogen fuel cells are more efficient than many other energy sources, including many green energy solutions. This fuel efficiency allows for the production of more energy per pound of fuel. For example, a conventional combustion based power plant generates electricity at 33-35% efficiency compared to up to 65% for hydrogen fuel cells. The same goes for vehicles, where hydrogen fuel cells use 40-60% of the fuel’s energy while also offering a 50% reduction in fuel consumption.
Hydrogen fuel cells do not generate greenhouse gas emissions as for fossil fuel sources, thus reducing pollution and improving air quality as a result.
With almost no emissions, hydrogen fuel cells do not release greenhouse gases, which means they do not have a carbon footprint while in use.
The charge time for hydrogen fuel cell power units is extremely rapid, similar to that for conventional internal combustion engine (ICE) vehicles and markedly quicker in comparison tobattery-powered electric vehicles. Where electric vehicles require between 30 minutes and several hours to charge, hydrogen fuel cells can be recharged in under five minutes. This fast charging time means that hydrogen powered vehicles provide the same flexibility as conventional cars.
Hydrogen fuel cells do not produce noise pollution like other sources of renewable energy, such as wind power. This also means that, much like electric cars, hydrogen powered vehicles are much quieter than those that use conventional internal combustion engines.
Some low-carbon energy sources, including wind energy and biofuel power plants can be an eyesore, however, hydrogen fuel cells do not have the same space requirements, meaning that there is less visual pollution too.
Hydrogen fuel cells offer greater efficiencies with regard to usage times. A hydrogen vehicle has the same range as those that use fossil fuels (around 300 miles). This is superior to that currently offered by electric vehicles (EVs), which are increasingly being developed with fuel cell power units as ‘range-extenders’. Hydrogen fuel cells are also not significantly impacted by the outside temperature and do not deteriorate in cold weather, unlike EVs. This advantage is increased further when coupled with the short charging times.
Where local conditions allow, the availability of hydrogen through local generation and storage could prove to be an alternative to diesel-based power and heating in remote areas. Not only will this reduce the need to transport fuels but will also improve the lives of those living in distant regions by offering a non-polluting fuel obtain from a readily-available natural resource.
As the technology advances, hydrogen fuel cells will be able to provide energy for a range stationary and mobile applications. Hydrogen powered vehicles are just one example, but it could also be used in smaller applications such as domestic products as well as larger scale heating systems. Similar to ICE powerplants, the functions of energy storage capacity (ie. the fuel tank) and engine size are decoupled, in contrast to battery-based power (ie. for which power scales linearly with mass), thus providing great flexibility in design.
Hydrogen fuel cells have the potential to reduce the dependency of a nation on fossil fuels, which will help democratise energy and power supplies around the world. This increased independence will prove a benefit for many countries who are currently reliant on fossil fuel supply. Of course, this will also avoid the problem of rising fossil fuel prices as stocks reduce.
