More than 80 different concept, demonstrator and/or test-fleet fuel-cell-powered electric vehicles have been fielded by 25 different automakers around the globe since General Motors unveiled the first, its GM Electrovan, in … yes, 1966. There also have been a host of 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 and other structures. According to 4th Energy Wave’s (Caldbeck, Cumbria, UK) report, the Fuel Cell and Hydrogen Annual Review, 2015, installed fuel-cell systems have totaled 1 GW since 1995. The market research firm predicts that the second installed GW, however, will be achieved in very short order, by 2016-2017. Although 4th Energy Wave is tracking transportation sector growth since release of the first production fuel cell vehicles (FCVs) in 2014, and more forecast to appear in 2015 and 2016, it’s offering a cautious global forecast of only 66,500 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 (see “Pressure vessels” under “Editor’s Picks”) and other system components of proton exchange membrane (PEM) fuel-cell systems, still the leading system 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 over metals in high-temperature and low-temperature PEM fuel cells, where power density is a secondary requirement. Chopped carbon fiber and graphite particle-filled/vinyl ester bulk molding compounds (BMCs) are finding wide use in bi-polar plates for low-temperature PEM fuel cells. BMC cost has declined significantly as volumes have increased. Similarly, molding cycles once measured in minutes are reportedly now completed routinely in seconds, due to BMC formulation improvements and the capability to make thinner plate cross sections.
That’s the future. For now, automakers anxious to meet looming CAFE and CO2 emission standards have spurred production of battery packs lightweighted with composites. Electric cars have lacked the driving range of their gas- and diesel-powered counterparts due, in part, to battery weight. General Motors’ Chevy Volt and Spark benefit from a new generation of lithium-ion batteries. The Volt’s rechargeable energy storage system is housed in a glass fiber-reinforced thermoplastic battery pack with an integrated, fluid-cooled thermal management system. The Spark recently inspired development of a multimaterial battery case with significant use of composites (see “Onboard protection: Tough battery enclosure” under “Editor’s Picks”).