The purpose of switching from fossil fuels to low-emission alternative fuels is to mitigate climate change by reducing a country’s total carbon dioxide emissions, which in turn, will contribute to reducing total global emissions. There is a lot of talk about switching to cleaner forms of energy, and solar and wind energy are naturally the ones we gravitate towards as we are being made aware of these forms more than others. However, the discovery and development of hydrogen fuel cells may just revolutionise the sustainable energy sector.
A fuel cell is a device that generates electricity through an electrochemical reaction, not combustion. Due to their chemistry, fuel cells are very clean. Fuel cells that use pure hydrogen fuel are completely carbon-free, with their only by-products being electricity, heat, and water. Fuel cell systems are a clean, efficient, reliable, and quiet source of power. Fuel cells do not need to be periodically recharged like batteries, but instead, continue to produce electricity if a fuel source is provided. In the fuel cell, hydrogen and oxygen are combined to generate electricity, heat, and water. A fuel cell is composed of an anode, the positively charged electrode, cathode, the negatively charged electrode and an electrolyte membrane which keeps the hydrogen and oxygen separate. A typical fuel cell works by passing hydrogen through the anode of a fuel cell and oxygen through the cathode. At the anode, a catalyst splits the hydrogen molecules into electrons and protons. The protons pass through the porous electrolyte membrane, while the electrons are forced through a circuit, generating an electric current and excess heat. At the cathode, the protons, electrons, and oxygen combine to produce water molecules. As there are no moving parts, fuel cells operate silently and with extremely high reliability.
Fuel cells are used today in a range of applications, from providing power to homes and businesses, keeping critical facilities like hospitals, shops, and data centres up and running, and moving a variety of vehicles including cars and buses. Interestingly, NASA has used liquid hydrogen since the 1970s to propel space shuttles and other rockets into orbit. Hydrogen fuel cells power the shuttle’s electrical systems, producing a clean by-product – pure water, which the crew drinks. In September 2020, Airbus, a designer, and manufacturer of industry-leading commercial aircraft revealed three different concepts for the world’s first zero-emission commercial aircraft which could become available by 2035. These concepts each represent a different approach to achieving zero-emission flight by exploring various technology pathways to support the company’s ambition of leading the way in the eradication of fossil fuels in the entire aviation industry. All of these concepts rely on hydrogen as a primary power source – an option which Airbus believes holds exceptional promise as clean aviation fuel and is likely to be a solution for aerospace and many other industries to meet their climate-neutral targets.
However, when we consider the benefits of hydrogen fuel cells, aren’t there any negatives to producing energy this way? Unfortunately, the answer is yes. Even though using the hydrogen in itself is does not harm the environment, the process of producing it is. Hydrogen is the simplest and the most abundant element in the universe but does not occur naturally as a gas on the Earth – it is always combined with another element. For example, it is combined with carbon to form methane (CH4). So, to obtain the hydrogen, a lot of energy must be used to split the molecules that they are in. Steam methane reforming, or SMR, is the most common method for producing hydrogen on a large industrial scale. It involves reacting methane, found in natural gas, with steam (H20) to produce the hydrogen and carbon monoxide (the carbon monoxide must undergo further reactions as it is toxic which also produces more hydrogen). Although methane is being used, machinery driven by SMR-sources hydrogen is still cleaner than their fossil fuel equivalents
So, is there a future for greater use of hydrogen fuel cells in our everyday lives? The transportation sector has been dominated by fossil fuel-based fuels for much of the past century, due to their combined advantages in cost and energy density. This is what has made us very reliant on this form of energy. Although hydrogen is a very light gas, it is very difficult to transport. When speaking about oil, it can be transported through pipelines. When discussing coal, these can be transported in the back of trucks. When talking about hydrogen, however, just moving even small amounts is a very expensive matter. For that reason alone, the transport and storage of such a substance is currently considered impractical and very expensive. As technology develops and a way can be found to reduce the volume of hydrogen for much cheaper transportation and storage, we may be able to move from petroleum-based energy to hybrid and hydrogen power.