A new porous metal material with a similar structure to bath sponge could be the key to storing more hydrogen gas in cars, scientists say.
US researchers have created the aluminium-based sponge-like material for use in hydrogen fuel cells.,
Just one gram of the material has billions of holes, giving it a surface area of a whole football pitch.
This lets it store enough gas for typical storage capacities of today’s hydrogen cars, replacing the need for large and heavy tanks.
The research team says the device solves an industry problem of keeping hydrogen storage light and compact, while also having a large capacity.
The sponge could be used in hydrogen fuel cells and help overcome one con of the greener technology – high storage pressures
‘It’s like a bath sponge but with very ordered cavities,’ lead researcher Professor Omar Farha, from Northwestern University in the US, told the BBC.
‘With a sponge, if you spill water and you wipe it, in order to reuse the sponge, you squeeze it.
‘With this material we use the same thing – we use pressure to store and release these gas molecules – so, it works exactly like a bath sponge, except in a very smart programmed way.’
The sponge, called NU-1501-M, has been built from metal ions that assemble to form highly crystalline, porous frameworks.
For cars to carry enough hydrogen to power a journey, the gas has to be compressed and stored under high pressures in tanks.
Pictured, a hydrogen fuel cell. Hydrogen is used to power cars and trucks as an environmentally-friendly alternative to fossil fuels
Storing hydrogen at high pressures has been seen as one of the main drawbacks of fuel-cell cars, as it uses up more energy.
Even under high pressure, cars carrying around four to five kilograms of the gas can travel just over 300 miles (500 kilometres) before needing to refill.
But this new device can store large quantities of hydrogen within its pores and deliver them to the engine of the vehicle at lower pressures than current fuel cell vehicles.
Hydrogen produces only water when it is burned and is considered an ideal solution to cutting carbon emissions from petrol or diesel vehicles.
It has three times more energy than petrol per unit of weight and could power cars, planes and other vehicles that currently use hydrocarbons.
According to the US Environmental Protection Agency, the transportation sector generates the largest share of greenhouse gas emissions.
Backers of hydrogen fuel and fuel cells hope that they can find a way to make their usage both sensible and economic. Pictured, a hydrogen pump apparatus, with a design similar to a fuel pump in a traditional gas station, at an experimental consumer hydrogen filling station for fuel cell emission-free cars, in San Ramon, California
Hydrogen cars have been touted as one way to provide zero-emissions travel, replacing the use of fossil fuels in cars, such as gasoline and diesel.
Unlike fully electric or plug-in hybrid vehicles, hydrogen fuel cell vehicles don’t get power from a built-in battery that need to be charged for hours from an external power source.
When hydrogen reacts with oxygen from the air in the vehicle’s fuel cell, it releases electrical energy to power the car, as well as heat and water vapour through the exhaust.
When hydrogen burns, it doesn’t produce carbon dioxide, contrasting to today’s fossil fuel-powered cars.
However, current methods of producing hydrogen are a main barrier to further uptake of the green technology.
‘Since hydrogen is not mined or pumped out the ground like fossil fuels, we have to produce it,’ said Professor David Ryan at the University of Massachusetts’ Department of Chemistry.
‘Current methods of doing that are expensive and inefficient.
‘This, coupled with the lack of needed infrastructure, has hampered the transition from a petroleum to a hydrogen economy.’
The research team behind the new sponge-like material say it has surpassed targets set by the US Department of Energy.
The device has been detailed further in the journal Science.