Next steps for fuel cell technology

  • 07-Mar-2014 11:33 EST
Intelligent Energy02-14 Dennis Hayter_IE fuel cell taxi.jpg

Intelligent Energy's Dennis Hayter with a FCEV London taxi. The company is part of the HyTEC (Hydrogen Transport for European Cities) consortium to trial fuel-cell-powered cabs using proton membrane exchange (PEM) technology. London mayor Boris Johnson wants all new taxis in the city to have a zero-emissions mode beginning January 2018.

“No company in the automotive industry yet has the processes and designs to ramp up production of fuel-cell electric vehicles [FCEV] to 100,000 units per year by 2025," noted fuel-cell technology development expert Dennis Hayter. "However, there is a key point of agreement amongst leading automakers including Toyota, Hyundai, Honda and Daimler, that fuel cell technology has matured sufficiently to begin to provide a viable alternative to the internal combustion engine.”

Hayter, who is Vice President at U.K.-based Intelligent Energy, said there now is industry consensus of the need to get from Generation-1 to Generation-2 FCEVs, to cut costs, and to provide class competitive zero-emission vehicles (ZEV). “It means focusing on designing for manufacture and scale production, an iterative process mobilizing a broad ecosystem of suppliers, designers , process and manufacturing engineers,” he said.

The ongoing FCEV debate has been a complex roller-coaster ride for the industry. Since the 1990s, advocates have viewed FCEVs as a near-perfect solution for clean-energy transport needs. For some years the advances required to ensure their viability and affordability appeared to be converging on the technology roadmap. Various concept vehicles were produced (and many were driven by the editors of Automotive Engineering).

But the realities of cost and infrastructure-development, and the industry's focus on competing technologies such as advanced ICEs and hybrids pushed deployment hopes further and further out, to 2020 and beyond. Hayter’s cautious 2025 projection for global production (see accompanying graph) might prove fanciful, even given the FCEV's potential in the U.S. There, development is pinned to the so-called "ZEV mandate" driven by California and nine other states representing roughly one-third of the U.S. auto market. The law calls for 15% of new vehicle sales to be EVs/FCEVs by 2025.

OEM collaboration accelerates

What is clear is that for FCEVs to become financially and technologically viable, the industry must collaborate as never before, sharing components and production methodologies. Hayter noted the Daimler-Nissan-Ford alliance to develop a fuel cell stack and balance of plant components to allow enhanced performance at reasonable cost. GM and Honda have a similar arrangement with the primary goal of shared cost reduction.

Manufacturers are also working together to address issues such as standardization, safety, and regulatory arrangements, through industry activities such as the regional European H2 Mobility Initiative projects in Germany, the U.K. and France, as well as the EU-supported Fuel Cells and Hydrogen Joint Undertaking (FCHJU). All have agreed targets to bring vehicles to consumers.

As part of this collaboration, Intelligent Energy and other fuel-cell specialists have focused on developing stacks and systems with higher power densities and targeted at enhanced reliability, better quality assurance, performance /weight, and design for production, as they pursue the twin goals of meeting automotive performance requirements and convincing reliability for mass-market deployment.

Although challenges certainly remain, Hayter admitted, there are a growing number of FCEV examples proving that reliability and performance objectives can be met. They include fuel cell buses operated in Vancouver (around 2m km/1.2 m mi covered), and in London (close to 1m km) and other European and U.S. cities. Mercedes-Benz’s B-Class FCEV fleet has completed an around-the-world trial covering 3.3m km/ over 2 m mi); and the day-to-day operation of small FCEV fleets in limited public use in California.

“However, these reliability and performance objectives need to be met at a reduced cost/price point,” he stressed. “Power density of the fuel cell stack is a crucial factor. It offers a cost reduction [less expensive materials] and easier packaging; it can simplify control with fewer components, and it reduces the overall mass of the vehicle, affecting the fuel consumption and performance much as an ICE would.”

IE’s newly developed 50-kW fuel cell system has been developed as a potential base unit for a broad range of vehicles and it can be doubled-up to provide 100 kW. Working with Suzuki, Intelligent Energy has also developed a ready-to-scale production plant in Yokohama for fuel cell systems, called SMILE FC System Corp.

"Together, we have developed air-cooled automotive fuel cells for production, using experience gained in manufacturing fuel cells for the consumer electronics market," Hayter explained. "We have applied this to reduce the rejection rates and improve the manufacturability of closed cathode fuel cells. I have no doubt a fuel cell system exposed to the same level of production process scrutiny as a tablet computer would end up looking very different and costing very considerably less after a year or two.”

Technical challenges

Control system integration and tuning is essential for FCEV success. Said Hayter: “Intelligent Energy’s fuel cell system has its own controller with approximately 30 sensors used to track key parameters (temperature, stack voltages, airflow) that communicate with the master vehicle controller by CAN. We have seen situations where unknown error codes from the master controller have caused the fuel cell system to shut down to protect the fuel cell stack from overheating that could cause degradation or damage components."

He noted that systems integration is crucial for bringing the new FCEV components together.

As well as all the safety requirements of conventional vehicles, FCEVs operating at up to 300V bring added challenges. Electrical systems must be adequately isolated and protected, noted Hayter. And hydrogen fuel stored at 700 bar (10,000 psi) leaves the tank at only 3-7 bar (43-101 psi). Design and validation to protect the fuel system against the effects of extreme vibration and crash situations are critical issues facing manufacturers, he added.

Through-life reliability is a must for convincing FCEV solutions. OEMs and fuel cell system developers have already made “considerable” investments to understand degradation and failure modes of existing stacks, resulting in improvements and component count reduction for next generation technologies, stated Hayter.

Recent advances in the power density of fuel cell stacks have been significant. According to Hayter, Intelligent Energy’s proprietary stacks have demonstrated continuous volumetric and gravimetric power densities of 3.7 kW/L and 2.5 kW/kg, respectively. Further substantive improvements in FCEV technology are expected to be achieved, particularly at system level with new material approaches and designs.

Range is the bête noire that stalks pure EV multi-role credibility, but 500 km (310 mi) is now typical for current FCEVs, with Toyota working towards 700 km (435 mi). “We expect 800 - 1000 km [500-621 mi] to become the norm in the next generation of vehicles, which is probably about five years away,” Hayter estimated.

Of course, even with increasing range per vehicle, the growing fleet of FCEVs will need plenty of hydrogen refueling stations (HRS). Hayter believes too many refueling stations installed in the early days will create unutilized HRS assets, perhaps limiting FCEV deployment. The U.K.’s H2 Mobility Initiative identified a minimum national initial network of 65 HRS facilities growing to 1150 by 2030 to support a fleet of 1.6 million FCEVs. The industry-led German H2 Mobility Initiative has targeted a nationwide hydrogen refueling network of 400 HRSs, with plans to move from the current 15 to 100 over the next four years, Hayter observed.

He noted that California has shown similar commitment with the signing of the Alternative Fuel and Vehicle Technologies bill (AB 8). It sets aside $20 million a year to fund at least 100 HRSs through the end of 2023. And Japan plans 1000 HRSs to support two million FCEVs by 2030.

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