Hydrogen Fuel Cells: Water Batteries of the Future
I never experienced the fun of potato batteries in middle school science class, but the concept remains the same, whether a potato battery, or the batteries powering your computer, car, and city. Batteries convert chemical energy to electric energy. Electrolytes allow ions to move from one terminal to the other, creating a current of electrons from the anode (negative) to the cathode (positive) ends. The most common batteries are lithium cells, which use lithium as anode and manganese dioxide as cathode. Eventually, the anode lithium ions are depleted, and the battery must be discarded, or re-charged by reversing the reaction to restore lithium ion concentrations back to the anode(1).
Hydrogen fuel cells use hydrogen gas (H2) plus atmospheric oxygen (O2), and react the two together to produce water (H2O), electricity, and heat. Hydrogen fuel cells are considered more environmentally friendly than traditional combustion engines, which use fossil fuels crudely extracted from the earth to produce electricity, heat, and carbon dioxide waste products(2, 3). Oxygen is abundantly available in earth’s atmosphere due to millions of years of cyanobacteria and plant photosynthesis, while hydrogen gas can be generated by cheap, green, water electrolysis. Hydrogen fuel cells are also more efficient than combustion engines in bypassing the conversion of chemical energy into heat for mechanical work, by using direct chemical energy for mechanical work. Advances in superconductor technologies also make electron transport from hydrogen fuel cells feasible over long distances for powering cities unable to take advantage of solar, geothermal, hydroelectric, or tidal energy. Also impressively, solar, wind, and tidal-powered water electrolysis facilities can be built around the globe to produce renewable hydrogen gas for hydrogen fuel cells.
So, if this clean technology exists, what is delaying hydrogen cars and power grids? First, storage safety was a major concern, especially considering parallels with the hydrogen bomb. However, developments of strong, nanostructured carbon polymers, which allow safe storage of large amount of hydrogen gas at room temperature, alleviated bulk shipping anxieties(4, 5). Currently, the last major hurdles are infrastructure and market concerns, such as building convenient, accessible hydrogen gas filling stations the likes of those seen for petrol. Nonetheless, once hydrogen fuel demands surge, infrastructure changes become inevitability in a free-market.
Safety concerns out of the way, several car companies already have functional, hydrogen fuel cell cars. In July 2015, BMW unveiled its i8 prototype, modified 5 Series GT, which is an emission free, fuel-cell electric vehicle (FCEV) with direct-water injection. This prototype is powered solely by hydrogen gas, can go from 0-100km/h in six second, and has a maximum speed of 124 mph(6). Although hydrogen tank storage is still a limiting factor, innovations with nanostructured carbon polymers will only see an improvement in future capacities and performance. The 2016 Toyota Mirai, also a hydrogen fuel-cell car, stores high-pressure hydrogen gas in two carbon-fiber tanks, which is this model’s biggest advantage over previous prototypes. The Mirai completely refuels in five minutes or less(7). Hydrogen fueling station availability is the current draw back, thus the Toyota Mirai is only being sold in areas of California that presently have hydrogen stations. Yet, once hydrogen fuel availability is on-par with diesel, emission-free, renewable energy cars will be the 21st century answer that internal combustion engines were for the 19th and 20th. I look forward to more amazing discoveries, engineering innovations, and feats of marvel to ever-expand sustainability with scientific achievement.
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- Sitharaman, B., Shi, X., Tran, L. A., Spicer, P. P., Rusakova, I., Wilson, L. J., and Mikos, A. G. (2007) Injectable in situ cross-linkable nanocomposites of biodegradable polymers and carbon nanostructures for bone tissue engineering. J Biomater Sci Polym Ed. 18, 655–71
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- Anthony, S. (2015) BMW shows off first hydrogen fuel cell cars: Crazy i8 prototype, 5 Series GT. Cars Tech. [online] http://arstechnica.com/cars/2015/07/bmw-shows-off-first-hydrogen-fuel-cell-cars-5-series-gt-crazy-i8-prototype-2/ (Accessed July 8, 2015)
- Evarts, E. (2015) Driving the 2016 Toyota Mirai—on the hydrogen highway. Consum. Rep. [online] http://www.consumerreports.org/cro/news/2015/04/2016-toyota-mirai-hydrogen-fuel-cell-car/index.htm (Accessed July 8, 2015)
#science #chemistry #energy #green #innovation
Valjean R. Bacot-Davis.