Climate change: ‘Bath sponge’ breakthrough could boost cleaner cars
A new material developed by scientists could give a significant boost to a new generation of hydrogen cars.
Like a bath sponge, the product is able to hold and release large quantities of gas at pressure and lower costs.
Containing billions of small pores, a single gram of the new aluminum-based material has a surface the size of a football pitch.
The authors say it can store the large volume of gas needed for practical travel without the need for expensive tanks.
Auto sales, especially larger SUVs, have grown in the United States in recent years.
In 2017, CO2 emissions from cars, trucks, planes and trains outpaced power plants as the main source of greenhouse gas emissions in the United States.
In addition to the development of electric vehicles, much attention has been paid to hydrogen as a zero-emission energy source for cars.
Gas is used to fuel a fuel cell in cars and trucks and, if produced with renewable energy, it is a much more environmentally friendly fuel.
However, hydrogen powered vehicles have some drawbacks.
The gas is extremely light: in normal atmospheric pressure, to transport 1 kg of hydrogen that could fuel your car for over 100 km, you would need a tank capable of holding about 11,000 liters.
To overcome this problem, gas is stored at high pressure, around 700 bar, so cars can carry 4-5 kg of gas and travel up to 500 km before refueling.
This pressure level is about 300 times greater than a car’s tires and requires specially made tanks, all of which increase the cost of the vehicles.
Now, researchers believe they have developed an alternative method that would allow the storage of high volumes of hydrogen at a much lower pressure.
The team designed a new highly porous material, described as a metal-organic structure.
The product, with the glamorous name of NU-1501, was built from organic molecules and metal ions that self-assemble to form highly crystalline porous structures.
“It is like a bath sponge but with very neat cavities”, said prof. Omar Farha, of Northwestern University in Evanston, United States, who led the research.
“With a sponge, if you pour water and clean it, 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 clever programmed way.”
The key capability of the new framework is that it can potentially store hydrogen and other gases at much lower pressures without needing a huge tank.
“We are able to store huge quantities of hydrogen and methane inside the pores of the metal-organic structure and deliver them to the vehicle’s engine at pressures lower than those necessary for the current fuel cell vehicle,” said Prof . Farha.
His team has gained experience in developing these adsorbent materials for the United States Department of Defense, to protect soldiers from nerve gas attacks,
Researchers say funding is now available to develop this type of material for transportation applications.
The new material has already exceeded the fixed targets set by the United States Department of Energy for onboard storage and delivery of alternative fuels.
But to go further, scientists will need a significant buy-in from automakers.
The the research has been published in the journal Science.
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