Since the second industrial revolution, the use of fossil fuels has skyrocketed, but it wasn’t until 1968 that the world learned about the adverse effects of climate change caused by burning fossil fuels such as coal, oil, and gas. The report presented to the American Petroleum Institute by Stanford Research Institute stated:
“If the Earth’s temperature increases significantly, several events might be expected to occur, including the melting of the Antarctic ice cap, a rise in sea levels, warming of the oceans, and an increase in photosynthesis.” (O. Milman, 2016)
Fossil fuels in transportation
The awareness around the topic grew, and the Firth Earth Day was observed in 1971. Since then, there have been several awareness campaigns and policy-making initiatives to promote the use of sustainable energy options such as solar power. But as the graph shows below, the highest contribution towards the use of fossil fuels is from the transportation sector.
Multiple alternatives like solar power, hydropower, and wind have gained popularity for electric power. However, because these methods require enormous setup, they failed to impact the transportation sector, including fuel for cars, trucks, ships, and aviation.
Electric Vehicles (EVs)
Feeling the need to create sustainable transportation methods, battery-powered systems were invented. Although the first practical electric vehicle (EV) was created in the 1890s in America, petrol-powered vehicles were used mainly due to the rise of internal combustion engines.
The modern EVs emerged into the market with the introduction of the Toyota Prius in 1997. With continuous research and development, the 2000s marked the revival of EV cars, battery-powered or hybrid systems (EVBox, 2023).
Since then, electric vehicles have gained massive popularity and now account for every 1 in 7 cars sold globally. All major automobile manufacturers like Tesla, Nissan, Mercedes, and BMW grabbed the opportunity and introduced new and better designs for cars and trucks.
In 2022, a net-zero, fully battery-powered cargo ship was introduced by the name of Yara Birkeland, which is 80 meters long and can carry a little over 100 containers. The first all-electric aircraft, Alice, also took its first flight in September 2022, created by the company Eviation.
Furthermore, tons of research is still being carried forward to improve battery systems to have higher capacity, lower maintenance, and lower costs.
Limitations of EV technology
Although international government bodies are endorsing the use of EV transportation, major concerns need to be addressed regarding this technology.
EV cars have a limited battery range. The latest Tesla Model 3 is advertised as having a battery range of 341 miles, which may differ depending on the driver. However, a petrol-fueled car can easily drive 300-400 miles in a full tank, and a diesel car may drive up to 700 miles.
The infrastructure around charging stations for EV cars is also underdeveloped. In many countries, including Pakistan, that is a significant hindrance for the masses not to buy complete EVs. Furthermore, charging times at these stations are also quite long. Fully charging an EV car can take up to 30-40 minutes, while a petrol or diesel-fueled vehicle can be refueled in 5 mins (S. Samarasinghe, 2024).
The biggest disconcertment with EV transportation is the manufacturing of batteries that use minerals like Nickel, Magnesium, Cobalt, Lithium, and Graphite, emitting huge amounts of greenhouse gases during mining.
This makes the production of these batteries have a more significant amount of carbon footprint compared to the production of internal combustion engines, i.e., petrol or diesel engines (Tallodi, 2022).
The Green Fuel Solution: Hydrogen
Due to technical and environmental issues in the EV sector, the automotive and aviation industry has started looking for zero-emission solutions like hydrogen. Hydrogen is a highly flammable gas that can be used in internal combustion engines like diesel and petrol. It will only produce water vapors as waste.
However, combustion hydrogen engines will not be utterly emission-free because they create excess heat that generates nitrogen oxides, which are harmful greenhouse gases. Combustion is also not a very efficient process due to the loss of energy as heat (J. Nebergall, 2022).
Another alternative way of using hydrogen as a fuel is using Hydrogen Fuel Cells. In these fuel cells, hydrogen and oxygen are supplied at pressure, and an electrochemical process occurs across a membrane, creating electricity.
This process also generates water vapors like hydrogen combustion engines. The electricity produced can be used to drive motors like in an EV, and this transportation system is called a hydrogen-electric powertrain (Sopp+Sopp, 2015).
A lot of research and development is going on about hydrogen fuel cells in the automotive and avionics industries. The first widely available car based on hydrogen fuel cells is the Toyota Mirai, launched in 2014.
Along with Toyota, Hyundai and Honda have also launched cars based on hydrogen fuel cells, and recently, BMW and Audi have displayed their concept cars, iX5 Hydrogen and Q5 FCEV, respectively, which are also based on similar technology.
Regarding global climate change, the aviation industry is also a significant contributor to the cause. Several efforts have been made to reach zero-emission aviation engines. In that pursuit, multiple aviation companies are also working on enhancing the hydrogen-electric power trains that are used for aircraft.
In fact, H2FLY, ZeroAvia, and Universal Hydrogen have successfully flown manned flights with hydrogen-electric power trains.
A deeper dive into Hydrogen Fuel Cells
Hydrogen fuel cell technology is still in the early stages of development and requires great engineering efforts to make it a good quality industrial product. The schematic diagram below demonstrates the basic workings of the PEM (Proton Exchange Membrane) Fuel Cell.
Hydrogen on the anode side splits into proton and electron; the proton goes through the membrane and combines with oxygen on the cathode side to create water, while the electrons gather up on the anode side, creating a potential difference between the cathode and anode. Multiple cells are assembled to create a fuel cell stack (University of Strathclyde).
The fuel cell stack design is highly complicated, mainly because of the Bipolar plates (BPPs). These plates are designed to meet the requirements for an efficient electrochemical reaction across the Membrane Electrode Assembly (MEA).
MEAs are sandwiched between BBPs, which ensures the correct quantity and pressure of gases to be fed to either side of the MEA. It simultaneously maintains enough contact for efficient electron transfer. Depending on the sealing method used, the BPPs should also be able to bear enough stress to support the compression required for the stacks to be leak-tight.
Furthermore, these MEAs used are damped in strong acid, which can easily corrode metal plates. So, another layer of protective coating needs to be applied to save the BPPs from corrosion. The plates are generally made from thin sheets of metal, which are created using press forming. This is also a complicated process because of the complicated design of the BPPs.
Apart from BPPs and MEAs, the temperature management system, water emission system, and pressure and mass flow regulation are also quite challenging. There are two types of Hydrogen fuel cell systems: Low-Temperature PEM fuel cells (LTPEM) and High-Temperature PEM fuel cells (HTPEM).
As the name suggests, with a water-based cooling system, the LTPEM system operates at lower temperatures, averaging around 80 degrees C. HTPEM operates at higher temperatures of around 180 degrees C with an air-based cooling system.
HTPEM systems are still in the prototyping stages but have shown better results compared to LTPEM, especially with high energy requirements like in a truck or an aircraft. HTPEM stacks are air-cooled, significantly reducing the overall system’s total weight.
As this technology is still emerging, it faces many challenges in making it widely available. The most common concern around hydrogen is safety because it is highly flammable, so its storage and the system need to be extremely safe for public use.
Secondly, the extraction of hydrogen from the electrolysis of water requires a lot of energy, which increases the price of hydrogen that can be used as fuel. The MEAs use precious metals like platinum and iridium as catalysts, which also add up to the overall cost.
Along with a lot of investment to build this technology and its infrastructure, an intensive regulatory framework is also required to convince government bodies that this technology is greener, more efficient, and safer to use (TWI).
The future of hydrogen-electric powertrains seems promising as many companies worldwide are investing vast amounts of money into this technology, and policymakers are providing guidelines and incentives to the companies to pursue this dream of the Net-Zero Emission energy system. Therefore, according to Forbes magazine, green hydrogen will become the 21st-century version of oil.
References
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- High-speed bipolar plate welding with FL-arm lasers: Coherent (2022) Coherent. Available at: https://www.coherent.com/news/blog/bipolar-plate-welding (Accessed: 02 June 2024).
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- Nebergall, J. (2022) Hydrogen internal combustion engines and hydrogen fuel cells | Cummins Inc.., Cummins. Available at: https://www.cummins.com/news/2022/01/27/hydrogen-internal-combustion-engines-and-hydrogen-fuel-cells (Accessed: 02 June 2024).
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- Samarasinghe, S. (2024) The shift from electric vehicles to hydrogen: Safety, reliability, and the future of Sustainable Transportation, LinkedIn. Available at: https://www.linkedin.com/pulse/shift-from-electric-vehicles-hydrogen-safety-future-samarasinghe-dizyf/ (Accessed: 02 June 2024).
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