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Next-Generation Fuel-Cell EVs Aim to Strengthen Case vs. BEVs

Dec. 14, 2020
Zero-emission challengers emphasize short refueling times and longer range.

What you’ll learn:

  • How hydrogen-powered fuel-cell EVs work.
  • Details about Toyota’s second-generation Mirai hydrogen-powered EV.
  • BMW’s plans for a 2022 model year fuel-cell SUV.
  • Advantages/disadvantages of an FCEV compared to a BEV.

 

While battery-electric vehicles (BEVs) such as the Tesla Model 3 dominate talk about zero-emission vehicles, automakers such as Toyota , BMW, and Hyundai are developing next-generation fuel-cell electric vehicles (FCEVs). Like BEVs, FCEVs also produce virtually no harmful exhaust emissions—they only emit water vapor and warm air. Unlike BEVs, though, FCEVs have one crucial difference: Hydrogen cars produce the electricity themselves.

FCEVs powered by hydrogen use a propulsion system similar to that of electric vehicles; the energy stored as hydrogen is converted to electricity by the fuel cell. Hydrogen is considered an alternative fuel under the Energy Policy Act of 1992 and qualifies for alternative fuel vehicle tax credits.

In a recently published report titled “Fuel Cell Electric Vehicle (FCEV) Market, Global Industry Analysis, Market Size, Opportunities and Forecast, 2020 – 2027,” Acumen Research and Consulting estimates that the global FCEV market is anticipated to grow at a CAGR of around 38% in terms of revenue during the forecast period 2020-2027.

Depending on the charging station and battery capacity, BEVs can require several hours for a full charge. The hydrogen tanks of fuel-cell cars, on the other hand, can be refilled and ready to go again in less than five minutes. An IDTechEx report on “Advanced Electric Cars” notes that the top fuel-cell car models are the Toyota Mirai with 300-mile range and the Hyundai Nexo with 413-mile range. Earlier in 2020, Tesla revealed a 400-mile (EPA) Model S, in response to competition from rival Lucid Motors, which later announced the Lucid Air BEV sedan would be the first production car with 500 miles of electric range. Thus, the range advantage that fuel-cell cars have been claiming may be short-lived.

Toyota’s first-generation Mirai introduced in 2014 was a four-door sedan, capable of 111 mph and 0 to 62 mph in 9.6 seconds, with a range of 300 miles from the 5 kg of hydrogen stored at 10,000 psi in two tanks under the rear seats. Refueling took five minutes. Toyota manufactures the carbon-fiber tanks, as well as the 153-bhp/247-lb-ft fuel cell.

Where the previous, front-wheel-drive model was based on a platform shared with older models of the RAV4, Corolla, and Prius, the new second-generation Mirai has a rear-drive platform based on the Toyota New Generation Architecture.

New Fuel Cell and Different Setup

The Toyota fuel cell also has been changed. There are now three two hydrogen tanks instead of two, mounted in a T-shape with a long tank along the center line and two located under and behind the rear seats. Between them, they hold a maximum of 5.6 kg of hydrogen gas compressed to 10,000 psi.

The new Mirai has a more compact and efficient hydrogen fuel-cell setup. The 24-liter fuel-cell stack consists of 330 cells producing 128 kW of electric power. That compares to the outgoing model with a 33-liter stack and 370 cells outputting 114 kW. The smaller power unit also means Toyota engineers were able to move it from the rear to the front, helping with weight distribution, styling, and balance.

With fewer cells and greater power, Toyota’s Gen 2 Mirai is more efficient in terms of space per kilowatt and output per cell. The fuel cells feed a new, more powerful (179 bhp/221 lb-ft) main drive motor. Its 0- to 62-mph acceleration time is reduced to 9.2 seconds; the top speed is also slightly less at 109 mph. Toyota has adopted lithium-ion for the buffer battery, which improves the fuel cell’s power delivery and recaptures braking energy. The tiny unit has an energy capacity of 1.24 kWh.

The new Mirai is bigger and has a significantly longer range of about 390 miles in real-world conditions. It’s expected to go on sale in 2021 at a price promised to be 20% lower than its predecessor to encourage what Toyota anticipates will be a tenfold increase in global sales from around 3,000 to 30,000 a year. 

Producing the Hydrogen

Hydrogen production requires electrical energy. This electrical energy is used to break water down into its constituent elements, hydrogen and oxygen, via the process of electrolysis. If the electricity used comes from renewable-energy sources, the hydrogen production has a neutral carbon footprint.

The most common type of fuel cell for vehicle applications is the polymer-electrolyte-membrane (PEM) fuel cell. PEM fuel cells aren’t new, having provided power for NASA’s Gemini space capsules in the 1960s.

In a PEM fuel cell, an electrolyte membrane is sandwiched between a positive electrode (cathode) and a negative electrode (anode). Hydrogen is introduced to the anode, and oxygen (from air) is introduced to the cathode. The hydrogen molecules break apart into protons and electrons due to an electrochemical reaction in the fuel-cell catalyst. Protons then travel through the membrane to the cathode.

Other Hydrogen Fuel-Cell Developments

Having been researching fuel cells for over four decades and in collaboration with Toyota since 2013, BMW is working with hydrogen fuel-cell technology, too. A new version of the BMW X5 SUV, called i Hydrogen NEXT, will be released starting in 2022 with Toyota providing the fuel cells

The i Hydrogen NEXT is an EV with two 700-bar hydrogen tanks arranged roughly in place of the transmission tunnel and under the rear seat. The powertrain will mix hydrogen from the tanks with oxygen to create electricity, which will power the SUV's 170-hp EV drivetrain. The BMW i Hydrogen NEXT will also feature a small battery above the electric motor, providing a 374-hp peak combined output.

The planned BMW i Hydrogen NEXT, continuously fed with hydrogen from CFRP tanks, will generate up to 125 kW of electrical energy for the electric motor, which sits on the rear axle. Two tanks, which together hold six kilograms of hydrogen, guarantee long range in all weather conditions—with a refueling time of only three to four minutes.

If you’re shopping for a hydrogen-powered fuel-cell SUV, the only option is the 2021 Hyundai Nexo. The Nexo has a cargo-space advantage over its closest fuel-cell rivals, which are both sedans.

With just a push of the Smart Key button, the Nexo Fuel Cell becomes a personal valet. Guided by 360 degrees of sensors, it can autonomously park in a parallel or perpendicular space with the driver inside—or outside—the vehicle. You can also use key-fob controls to remotely move it backward and forward.

Driving range is up to 380 miles per fill-up, but the only state that offers a hydrogen fueling infrastructure is California.  As a bonus, drivers will be able to drive along on free fuel for up to three years; Hyundai throws in $13,000 worth of fuel as part of the deal.

The Nexo boasts 161 hp and 291 1b-ft of torque. It’s available now and can be leased for $379 (Blue model) or $449 (Limited model) for 36 months. In addition, the first year of maintenance is free of charge.

In February 2020, Hyundai announced the expansion of its partnership with the U.S. Department of Energy to support the DoE Hydrogen and Fuel Cells Program. It addresses the technical barriers and works to accelerate the progress of hydrogen and fuel-cell technologies across a range of applications and sectors.

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