How Does Hydrogen Fuel Cell (HFC) Efficiency Stack Up to the Competition?
Transportation of passengers, goods, waste, and other cargo is critical for basic societal functions. Unfortunately, the majority of modern transport runs on fossil fuels. As such, these sectors are top greenhouse gas (GHG) contributors.
Vehicle electrification has been paramount in humanity’s search for cleaner and greener energy. However, powering electric vehicles (EVs) using traditional power grids still contributes to emissions. Moreover, heavy-duty mobility sectors—like aviation, maritime shipping, and off-road operations—are hard to abate with electric batteries alone.
Hydrogen fuel cell (HFC) technology has proven a viable solution to the clean mobility and energy puzzles that other alternatives can’t fill. As a zero-emission energy source with greater energy efficiency than EVs and internal combustion engines (ICEs), hydrogen has long been viewed as a fuel of the future, and it’s already seeing large-scale implementation in parts of Europe, the U.S., and Asia.
So, how exactly have HFCs been able to power the world’s most energy-demanding machinery better than conventional fuel sources? Read on to find out.
How Hydrogen Fuel Cells Generate Power
HFC technology is decades in the making and has come a long way from its early days.
Unlike conventional EV batteries, fuel cells generate power through an electrochemical reaction between hydrogen and oxygen. When pressurized hydrogen (either liquid or gaseous) is fed into a cell, it catalyzes this reaction to produce around one volt of electricity with heat and water vapor as the only byproducts.
Since most applications require much more than a volt, fuel cell stacks combine hundreds of them into a comprehensive energy production system. These stacks also convert the direct current (DC) output of the cells into alternating current (AC) electricity.
This current then powers whatever system it’s made for, ranging from a vehicle’s traction motor to a portable generator or stationary power station. Many of these systems also include a rechargeable battery to help capture and reuse surplus energy.
It would take a textbook to cover the pros and cons of each type of HFC, but the most widely used type in transportation are proton exchange membrane (PEM) fuel cells (AKA polymer electrolyte membrane).
PEMFCs are favored for transportation due to their low operating temperature, ease and safety of use, and production of highly pure hydrogen. Other varieties, like solid oxide fuel cells (SOFCs) and molten carbonate fuel cells (MCFCs,) are applied in large-scale power generation operations, where the minimum fuel purity threshold is lower.
What Impacts Hydrogen Fuel Cell Efficiency?
HFC efficiency is of utmost importance to virtually anyone considering integrating or switching to hydrogen technology. This key performance measure is relevant for logistics, engineering, cost analysis, and benchmarking against alternatives.
An FC system’s effectiveness at converting hydrogen into electricity is known as fuel cell efficiency and is typically expressed as a percent or ratio. Depending on the fuel cell and equipment design, efficiency ranges from 40-80%, with peak results obtained with combined heat and power (CHP) systems.
Much of the energy lost (50-60%) is due to waste heat, a problem faced by every fuel source. However, technological innovators are finding ways to reclaim waste heat productively.
Another key performance indicator is power output, or how much energy you can expect to generate. This metric will also vary widely depending on the model and application, but typical PEM stacks reach outputs of 100 kW and engines ranging anywhere from 200-2,000 horsepower.
An important measure for fleet management and transport logistics is well-to-wheel (WTW) efficiency, representing how much of the stored energy actually goes toward engine power. Studies find varied results based on the technology and testing methodology, but hydrogen fuel cell WTW efficiency has traditionally maxed out around 25-29% (including conversions of hydrogen to electricity to power).
Common contributing factors that influence HFC efficiency include:
- Fuel purity requirements
- Fuel compression density
- Ambient temperature and humidity
- Stack system and storage equipment quality
Hydrogen Fuel Cell Efficiency vs. Other Energy Sources
So, how do fuel cells stack up against other power sources?
Fuel Cells vs. Internal Combustion Engines (ICEs)
Depending on the method of measurement, HFCs currently meet or exceed the efficiency capabilities of traditional ICEs.
In terms of WTW efficiency, the technologies are at a meeting point near 30%. The main difference is that ICE technology has advanced as far as it can, given natural limitations. On the other hand, HFC technology is advancing rapidly thanks to investments from government and private sector entities.
Recent data has shown that “Hydrogen fuel cell vehicles consume about 29–66 % less energy and cause approximately 31–80 % less greenhouse gas emissions than conventional vehicles.”
With HFCs still being a relatively nascent market, experts remain optimistic that the technology can and will continue to improve in coming years.
Fossil fuel infrastructure is also rife with inefficiencies that lead to approximately two-thirds of all energy being wasted during production, transportation, and use. This again puts fossil fuels on par with or lagging behind hydrogen (depending on the production method).
Fuel Cells vs. Lithium-Ion Batteries:
In the competition between clean energy alternatives, fuel cell electric vehicles (FCEVs) are already outperforming lithium-ion battery electric vehicles (BEVs) on most measures.
However, one area where lithium-ion batteries shine is in energy conversion efficiency. The National Renewable Energy Laboratory (NREL) reported that BEVs only lose 15-20% of the energy used during operation (conversion efficiency of 80-85%).
Even after accounting for loss while converting hydrogen fuel into electricity, fuel cells are only able to convert about 60% of electricity produced into working energy. Diesel and gasoline range from 20-30% WTW efficiency for reference.
Still, hydrogen fuel leverages several advantages over conventional EVs:
- Energy density: Hydrogen’s high energy density by mass means it can pack more power in less space.
- As a result, the EV cars with the best range max out around 500 miles. Meanwhile, a Class 7 FCEV hydrogen truck recently set a world record for traveling 1,806 miles on a single fill.
- Refueling efficiency: Hydrogen-powered vehicles have refuel times comparable to gasoline and diesel.
- Though EV charging has come a long way, their batteries can take anywhere from 30 minutes to over a day to get a full recharge, depending on the equipment.
- Storage efficiency: Properly maintained hydrogen storage leaks at a slower rate than lithium-ion self-discharge.
- Lifecycle supply chain leakage for gaseous hydrogen was around 4.2% in 2022. Lithium-ion batteries self-discharge 5% of their stored energy within 24 hours.
Improving Fuel Cell Efficiency for Real-World Applications
Hydrogen has already proven a powerful resource for fueling, energy production, and infrastructural advancement. Yet hydrogen’s full potential has yet to be tapped, with scientists and engineers regularly finding new and innovative improvements.
Efforts for technological improvement will no doubt focus on achieving even greater fuel cell energy conversion and WTW efficiency rates. PEM technology in particular, due to its versatile and scalable applications, shows room for better efficiency with further research.
Hydrogen also presents logistical concerns in terms of sourcing, storage, and distribution. Due to its low volumetric density, hydrogen must be pressurized during storage and use. These drawbacks incur additional costs and infrastructural demands. Furthermore, hydrogen can only be as helpful as it is available, and production facilities are still limited in the United States.
However, noteworthy solutions are already being implemented. Hydrogen hubs, for example, provide all-in-one production, storage, and distribution. Hydrogen also has promising synergies with other clean energy sources, like using excess wind turbine power to make hydrogen with an electrolysis system.
Hydrogen’s capability for integration with other energy sources also makes it a top contender for grid stabilization efforts, especially those using intermittent renewable energy sources.
As municipal and corporate organizations race to advance hydrogen technology, we can expect the alternative fuel source to begin earning the recognition it deserves.
Build the Future of Mobility with Hydrogen Fueling Infrastructure
Hydrogen is quickly becoming the next leader of the clean energy transition. However, infrastructure must continue to spread to increase accessibility, supply, and affordability.
Over more than 30 years of energy expertise, FASTECH has developed over 40 hydrogen fueling stations and more than 250 compressed natural gas (CNG) stations.
No one does hydrogen infrastructure like FASTECH. Developers seeking engineering, procurement, construction, maintenance, or full-service hydrogen fueling solutions are encouraged to reach out via our contact form.
Let’s build a cleaner future.
