Proton-exchange membrane Fuel Cells combine hydrogen with oxygen from the air to transform chemical energy into electrical energy. Hydrogen is one of the most abundant elements in nature and one of the most cleanest form of energy. The residue of using Hydrogen as fuel is water. As long as you have hydrogen—the most abundant element on earth—the fuel cell can continue generating electricity. This can keep drones in flight and is also well-suited to power buses, trucks, and even spacecraft.
What is Proton Exchange Membrane Fuel Cell (PEMFC)
“Proton-exchange membrane fuel cells (PEMFC), also known as polymer electrolyte membrane (PEM) fuel cells , are a type of fuel cell being developed mainly for transport applications, as well as for stationary fuel-cell applications and portable fuel-cell applications.
Their distinguishing features include lower temperature/pressure ranges (50 to 100 °C) and a special proton-conducting polymer electrolyte membrane. PEMFCs generate electricity and operate on the opposite principle to PEM electrolysis, which consumes electricity. They are a leading candidate to replace the aging alkaline fuel-cell technology.
PEMFCs are built out of membrane electrode assemblies (MEA) which include the electrodes, electrolyte, catalyst, and gas diffusion layers. An ink of catalyst, carbon, and electrode are sprayed or painted onto the solid electrolyte and carbon paper is hot pressed on either side to protect the inside of the cell and also act as electrodes. The pivotal part of the cell is the triple phase boundary (TPB) where the electrolyte, catalyst, and reactants mix and thus where the cell reactions actually occur. Importantly, the membrane must not be electrically conductive so the half reactions do not mix. Operating temperatures above 100 °C are desired, so the water byproduct becomes steam and water management becomes less critical in cell design.” – Wikipedia
PEM fuel cells have high power density, which means they deliver more power per unit of weight. That makes them ideal for use in UAVs, where cargo weight and size are limited.
Applications of PEMFC
Its generally used in transportation primarily because of their low impact on the environment. Since there is no green house gas emission, its considered to be environmentally friendly solution; and also actively considered as an option to replace the current alkaline fuel cell technology which is a major polluter of the environment currently.
Another major reason why PEMFC is used is because of its ability to be a portable power generator. The power density is very high and their light weight means that the overall weight of the vehicle goes down drastically. This means lesser fuel consumption and better mileage. For vehicles that run on PEMFCs (which use compressed hydrogen as the fuel), they can operate at upto 40% efficiency. Its generally used in bigger vehicles like a bus or truck rather than a car becuase of the space available to house the entire system and the fuel.
PEMFC is actively considered in the Unmanned Aerial Vehicles (UAVs). This is because of the lightweight of the batteries and the heavy duty power available. UAVs are powered by batteries, which are heavy and limit flight distance. To add more power means using a heavier battery. Batteries also store energy and release it on demand, so UAVs often carry around more energy than they need. That’s why the UAV industry has been warming up to fuel cells, which generate energy only when required.
Challenges of PEMFC
The biggest challenge is making available the hydrogen fuel which if produced using the conventional fossil fuels totally defeats the purpose. PEMFC generally requires pure hydrogen for operation. But there are other fuel cells that run on methane and is generally more flexible. Also methane is much more easy to produce than hydrogen.
Current Usage of PEMFC
Companies like Nikola Motor Co, aims to be the Tesla of trucking. Nikola plans to launch a fuel cell truck model by 2021. Anheuser-Busch InBev (BUD) has already ordered 800 of them. Nikola says it will start delivering the trucks to the beer distributor in 2020. Nikola says that its trucks are supposed to get anywhere from 500 to over 1,000 miles on a full tank of hydrogen fuel, which gets used to power an electric motor. The trucks can be refueled in about 20 minutes, the company says. To support this and other future orders, Nikola says it’s planning to build “over 700 hydrogen stations” in the US and Canada by 2028. It’s working with Anheuser-Busch to develop the first 28 of those public hydrogen fueling stations.
This is not the first bet Anheuser-Busch has placed on medium-haul trucks powered by renewable energy, nor is it the company’s first flirtation with generating headlines by way of aligning with advanced technology. The beverage conglomerate recently preordered 40 of Tesla’s electric semi trucks. It also offered up 50,000 cans of Budweiser to be the first shipment on the self-driving trucks being developed by Uber.
Meanwhile, Tesla is also producing a semi truck, one that will offer a “million-mile” battery technology. Also, a lot of niche players are getting into the PEM technology. Overall, the fuel cell market is turning out to be an exciting opportunity where lots of cutting edge technology is being developed rapidly. We will hope to soon see them commercially available in the markets.