For years now, hydrogen’s potential as an alternative fuel has been getting car companies, policymakers and scientists rather excitable. It’s available in plenty, produces a lot of energy and almost no pollution.
But it has one big problem: There still isn’t a great way to store it, particularly on board vehicles.
Now, researchers from India’s Benaras Hindu University may have come close to cracking the puzzle—using coconuts.
A group of scientists led by Viney Dixit at the university’s Hydrogen Energy Centre have published the result of an experiment (pdf), where they used the solid endosperm of coconuts—the kernel, in layman’s terms—to store hydrogen.
Hydrogen storage is tricky (pdf) because it has a boiling point of -252.8°C in its liquid state. That means it needs to be stored at extremely low temperatures, which is expensive to ensure on board moving cars. In its gaseous state, it requires high pressure tanks that aren’t desirable in vehicles due to their size.
Instead, scientists have been exploring materials that can efficiently absorb (or adsorb) hydrogen and then release it when required—and carbon has emerged as a frontrunner among these.
At Benaras Hindu University, Dixit and his team are researching with carbon derived from coconut kernels, which contains fatty and organic acids as well as crucial light elements like potassium, magensium and sodium.
“It (coconut kernel) is not only abundantly found but is also cost-effective and can be converted into carbon easily. Unlike graphene, Carbon nano tubes (CNTs) and other type of carbons, the production of carbon from solid endosperm is not time taking. Therefore, its cost-effectiveness, good adsorption capacity and easy availability are its advantageous factors in regard to hydrogen storage,” the team explained in the paper.
Their experiments found that carbon from coconut kernels have “considerable hydrogen storage capacity”—2.30 wt. % (weight percentage) at room temperature and 8.00 wt.% at liquid nitrogen temperature under 70 atm (atmosphere) pressure—that can be attributed to the elements found in the kernel.
The US Department of Energy (pdf) estimates that hydrogen storage systems will need to have a capacity of 5.5 wt. % to be commercially viable, and it remains to be seen if the Benaras Hindu University’s research can match those requirements. Nonetheless, Dixit’s team hopes that their “present work is likely to initiate research on native light metal bearing carbon derived from natural precursors.”
Hydrogen-powered vehicles have been in the works for about two decades now. Hyundai is now leasing its hydrogen-powered fuel-cell version of Tucson in the US, while Toyota is working a $69,000 fuel-cell car called Mirai.
Last year, Nissan-Renault, Daimler and Ford partnered to develop a common fuel-cell system, with an eye on launching an affordable, mass-market vehicle by 2017.