The markets: Fuels cells and batteries (2019)

Although fuel-cell powered vehicles could still be in the automotive future, growth will be measured, and so will the market there for composite components. Composites for battery packs in electric vehicles will be the more immediate opportunity.

More than 80 concept, demonstrator and/or test-fleet fuel-cell-powered electric vehicles have been fielded by 25 automakers worldwide since General Motors (Detroit, MI, US) unveiled the first, its GM Electrovan, in … yes, 1966. There have also been a host of fuel-cell-powered trucks, buses, racing vehicles, a motorcycle, four rail locomotives and some ocean vessels, including submarines. Fuel cells also power an increasing number of stationary systems that provide heat and light to other structures. According to 4th Energy Wave’s (Caldbeck, Cumbria, UK) report, the Fuel Cell and Hydrogen Annual Review, installed fuel-cell systems have totaled more than 1 GW since 1995. It predicts a cautious global forecast of only 66,500 fuel cell vehicles (FCVs) by 2025, noting that “the adoption rate will be tempered by infrastructure issues [e.g., refueling stations and fuel sources] and by customer demand not being expected to really take off before the mid 2020s.” 

Composites can make up the bipolar plates, end plates, fuel tanks and other system components of proton exchange membrane fuel-cell (PEMFC) systems, still the leading type. In the past, thermoset materials were thought to be limited to lower volume and stationary applications, due to their longer mold cycle times, higher scrap rates and an inability to produce molded composite plates as thin as stamped metal plates. More recently, however, these issues have been overcome, providing a clear advantage for composites over metals in high-temperature and low-temperature PEMFCs where power density is a secondary requirement. Chopped carbon fiber and graphite- filled/vinyl ester bulk molding compounds (BMCs) are finding wide use in bipolar plates for low-temperature PEMFCs. BMC cost has declined significantly as volumes have increased. Similarly, molding cycles once measured in minutes are now routinely completed in seconds, due to formulation improvements and the ability to make thinner plate cross sections.

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Chopped carbon fiber is also finding use as a porous paper backing material for gas diffusion layers in PEMFCs. Prepared by wet laying chopped PAN-based fibers, these can be manufactured in high volumes and low thickness. SGL’s (Wiesbaden, Germany) SIGRACET gas diffusion layers are being used by Hyundai Motor Group’s (Seoul, South Korea) new NEXO fuel-cell vehicle. Accordingly, SGL has increased SIGRACET production at its Meitingen facility.

Toyota Motor Corp. (Tokyo, Japan) began selling its Sora fuel cell bus in March 2018, and it was the first such vehicle to receive type certification in Japan. The company plans to introduce more than 100 Sora fuel cell buses in Tokyo, ahead of the Olympic and Paralympic Games in 2020. Teijin Carbon (Tokyo, Japan) announced it has developed a multi-material roof cover for the Sora comprising carbon fiber composites, aluminum and engineered plastics. The part is manufactured in one piece with complex shapes and is suitable for mass production.

Meanwhile, the first hydrogen fuel cell passenger boat in the US was announced in July 2018. Bay Ship and Yacht Co. (Alameda, CA, US) has the contract to build the vessel for Golden Gate Zero Emission Marine (GGZEM, Alameda, CA, US) and expects it to be delivered and in service by September 2019. Power is generated by 360 kW of Hydrogenics (Mississauga, Canada) proton exchange membrane fuel cells and lithium-ion battery packs. Hydrogen tanks from Hexagon Composites (Alesund, Norway) installed on the upper deck contain enough hydrogen to provide energy for up to two days between refueling. 

Hydrogen tanks are indeed the largest opportunity for composites with fuel cells. At CW’s Carbon Fiber 2017 conference, Chris Red of Composites Forecasts and Consulting LLC (Mesa, AZ, US) predicted that the demand for carbon fiber in composite pressure vessels will grow from 5.4 metric tonnes (MT) per year in 2016 to 26 MT/yr in 2021 and 45 MT/yr by 2025. At this 2025 volume, composite CNG and hydrogen cylinders for fuel cell vehicles will consume almost as much carbon fiber as projected for wind turbine blades, 50% more than forecast for automotive, rail and other ground transportation chassis and body components, and twice what is estimated for aerospace. Red cited forecasts for 2.1 million hydrogen fuel cell vehicles to be produced from 2016 to 2025, corresponding to 3 million pressure vessels.

Type IV composite pressure vessels used to store hydrogen are made by filament winding carbon fiber and epoxy over a plastic liner. Highly automated turnkey tank production lines are designed and produced by composites equipment suppliers including MIKROSAM (Prilep, Macedonia) and Roth Composite Machinery (Steffenberg, Germany), with the latter claiming it has accelerated hydrogen tank production 5-10 times with its new Rothawin technology. Hexagon Composites is the leading producer, manufacturing composite hydrogen tanks for cars and light vehicles in Raufoss, Norway, and Kassel, Germany, and tanks for its mobile pipeline system as well as for medium- and heavy-duty trucks and buses in Lincoln, NE, US. It has vertically integrated through a merger with Agility Fuel Solutions (Costa Mesa, CA, US), sending tanks from Lincoln to Salisbury, NC, US, where they are integrated into complete alternative fuel systems and installed on trucks and buses. Hexagon composite hydrogen tanks are also used on boats, ships and rail vehicles, as well as in stationary power systems, and are now being investigated for aircraft. The company claims to be the second largest user of carbon fiber in the world, but it will begin to face increased competition as Plastic Omnium (Paris, France), a world leader in plastic exteriors and front end modules for cars, has begun developing hydrogen storage tank and fuel cell capability. In 2017, it bought Optimum CPV, a Belgian company that makes composite hydrogen storage vessels, and Swiss Hydrogen, which works in fluid and thermal management.

Even though Hexagon Composites claims that hydrogen fuel cells can provide power systems that are more lightweight and economical than many of the alternatives being developed, the automotive industry, for now, continues to put more of its eggs in the battery power basket. Though some market analysts claim composites are not needed for battery electric vehicles, others disagree. “There are a lot of electric motor applications for CFRP with tremendous opportunities for us,” said James Austin in an interview during his tenure as president of North Thin Ply Technology (NTPTPenthalaz-Cossonay, Switzerland), a developer of lightweight, spread tow and thin ply composite materials and manufacturing systems. “I think there is a lot more going on here than people appreciate. We think electric vehicles (EVs) will have a significant impact on the future of our company.”

One company showing the way is Williams Advanced Engineering (Grove, Oxfordshire, UK), which developed structural CFRP battery box enclosures for its lightweight and scalable FW-EVX vehicle platform. Located within the car’s aluminum and CFRP monocoque are 38 battery modules, providing the EV’s power. Each 136-mm-wide battery module contains 10 pouch-type lithium ion batteries (think thin, as for a laptop) supplied by LG Chem (Seoul, South Korea). Pouches are stacked and protected within a CFRP box. Each of the 38 battery module boxes are made using flat CFRP sheet and the highly automated 223 process that Williams is patenting. Portions of the sheet for the box faces are cured, leaving flexible uncured hinges in between. These allow for folding of the partially cured sheet into a box, followed by final cure and bonding to produce a rigid enclosure. Each box is an impact-resistant, load-bearing exoskeleton, aiding in crash safety. The boxes are positioned and secured together to provide significant torsional and bending stiffness through the monocoque, which allows designers to reduce weight in other structures, increasing the vehicle’s fuel economy and performance.

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