- Battery vs hydrogen fuel cell vehicles
Battery vs hydrogen fuel cell vehicles
While claims are made that focusing on either batteries or fuel cells is the only means by which to achieve mass market, industry trends increasingly show that battery-powered and hydrogen fuel cell vehicles are most powerful in combination, with each particularly useful in different applications.
Quick overview of batteries vs hydrogen fuel cells in passenger and commercial vehicles
|Batteries||Hydrogen fuel cells|
|Passenger vehicles||Smart phone model – use freely during the day and plug in at night||Not yet feasible – lacking infrastructure; high cost of H2|
|Commercial vehicles||Most useful for city-based delivery vehicles – short ranges and frequent stopping||In early adoption phase – likely to be widely used in future modeling current vehicles|
The Nissan LEAF, Chevrolet Bolt, and Tesla are all battery-powered electric vehicles (BEVs) that contain at least one rechargeable battery. To recharge, BEVs can be plugged into a standard household outlet to charge at a rate of ~2-5 miles per minute, or into a public fast-charging outlet to charge at a rate of ~25 miles per minute. While faster charging methods are in the works, this currently means BEVs charging at home will need to charge for at least 20 minutes to go 100 miles. Since most drivers are accustomed to getting 300 miles of fuel in about 5 minutes, this can take some getting used to.
But it works fairly well for people who begin and end each day at the same spot. Consider a commuter who drives about 12,000 miles a year, about 33 miles a day – they can easily charge their vehicles overnight much like one charges a cell phone. BEVs are also a viable option for commercial use, such as public transit and delivery vehicles, that have lower mileage routes and make frequent stops because batteries can efficiently manage the variable energy demand.
Challenges in battery technology
BEVs are most limited by the weight of the batteries themselves. Whereas doubling or tripling the amount of gasoline (or power to a fuel cell) will respectively double or triple the driving range, increasing the number of batteries quickly yields diminishing returns. Large and/or additional batteries can also be problematic for commercial vehicles that have maximum allowable axle weights. Research efforts to make lighter, more energy efficient batteries are underway.
Solutions to the long charging times are also being explored. One interesting area of research is in inductive charging, where fewer batteries are required because they can recharge while the vehicle is operating.
Hydrogen fuel cell-powered vehicles
Whereas BEVs likely aren’t a good option for a road trip, the less common fuel cell electric vehicles (FCEVs) are. FCEVs are significantly better suited for heavy-duty transport, whether long-haul trips or for vehicles with heavy loads.
For one, fuel cells have a much higher energy density than batteries, so the hydrogen tank can be much more compact and lighter than the equivalent fully charged batteries would be. (To visualize this: a 60 lb lead acid battery stores about 80 Ah of power, while a 20 lb propane tank with a 30 lb fuel cell generates about 3400 Ah of power). FCEVs are also able to refuel in only minutes, similar to a gasoline or diesel powered vehicle.
Challenges in fuel cell technology
Fuel cells are still significantly more expensive than either batteries or gasoline – currently about 3.5 times the cost of the most expensive gasoline in the US. There is also less infrastructure currently in place to support FCEVs.
Some of these cost issues will be addressed via economies of scale, as hydrogen becomes cheaper to manufacture and distribute. However, lithium and platinum availability for the fuel cells is somewhat limited, and recycling methods for fuel cells are required for them to be a truly green solution.
Are passenger vehicle manufacturers choosing BEVs or FCEVs?
In 2020, Horvath & Partners analyzed the efficiency of BEVs and FCEVs, comparing the amount of energy used for propulsion and the amount lost as heat. They showed that BEVs have 70-80% efficiency, whereas FCEVs only have 25-35% efficiency.
There are vehicle manufacturers on both sides of the debate between BEVs and FCEVs. All Tesla vehicles are BEVs. Volkswagen is primarily developing BEVs, but is using FCEVs for heavy-duty transport, aviation, and shipping vehicles. And Honda, Hyundai, and Toyota are all moving toward FCEVs, seeing a lot of promise in the development of fuel cell technology.
Currently, California is the only state with the infrastructure to support FCEVs – so several new developments have taken place there. In 2015, Toyota introduced the Mirai, a family FCEV, to California. In 2018, Honda sold or leased 624 Clarity Fuel Cell vehicles, and worked with Toyota and a subsidiary of Shell Oil to build hydrogen fueling stations in California. Meanwhile, Hyundai’s FCEV has a higher range than any BEV currently on the market, and the company is looking to the northeastern US as the next market to expand into.
Are these truly green solutions?
Battery and fuel cell vehicles both introduce significantly less carbon into the air than traditional combustion engines, but they aren’t perfect solutions.
Batteries require mining for cobalt, lithium, nickel, and copper, posing threats to both worker and environmental safety. Recycling batteries would limit the amount of mining necessary, but itself produces large amounts of carbon dioxide (although significantly less than do our current combustion engines).
Hydrogen fuel cell vehicles do tend to be more environmentally friendly overall, but both BEVs and FCEVs are only as green as the energy used to power them. Some BEVs are powered using electricity from wind or solar power, but others still rely on coal. And most hydrogen used for FCEVs is still produced from natural gas. For either of these to be truly green solutions, the electricity running them must be produced in a clean, carbon neutral way.
Food for thought: Are we sacrificing short-term environmentalism?
In most of the world, there is limited infrastructure in place to support the adoption of BEVs and FCEVs at scale – and building out that infrastructure is unlikely to be a carbon-neutral effort. As such, there is an argument to be made that short-term work should focus on increasing the efficiency of combustion engines, which the vast majority of consumers are still purchasing and driving until their inevitable phase out.
Both technologies have a role in emissions-free vehicles
Fuel cells generate energy that can be stored in batteries and supplied in a controlled manner, so these technologies are well suited to work together in all sorts of vehicles.
Meanwhile, the largest challenge remaining is building the infrastructure to support either or both of these technologies, enabling them to be adopted at scale. Both are currently used in specific niches, with battery-powered passenger vehicles expensive but gaining market share, and hydrogen fuel cell vehicles gaining traction: for instance, forklifts used at warehouses and distribution centers (including those of Amazon and Walmart) at locations across the country.