Solar device that takes pressure off doctors

This rather unassuming looking set-up on a research station roof in Mumbai, India, could play a part in improving medical services in remote areas.

US engineers have found that by integrating a transparent, cloud-like aerogel into a solar heater they can efficiently trap solar energy to generate steam that is hot enough and at high enough pressure for sterilising medical instruments even in hazy and partly cloudy conditions.

The secret is in the special insulating gel, which reduces heat loss, allowing the system to provide the grunt that autoclaves – which work a bit like pressure cookers – need to reach and maintain 120+ degrees Celsius and 205kPa.

“When we were doing the field research in India, many healthcare providers said that they can operate an autoclave if there is reliable energy, but there are certain occasions where the electricity is unavailable,” says Lin Zhao from Massachusetts Institute of Technology, first author of a paper in the journal Joule.

“They are then forced to use maybe unsterilised equipment, or they have to use some rudimentary method like boiling water to try to sterilise things. A solar-powered device, in that case, would certainly be helpful to them.”

Unlike other steam-generating solar thermal devices, it does not rely on solar tracking to concentrate sunlight, so can remain stationary, the researcher report. In the field trials it generated steam at 100 degrees with more than double the energy efficiency other devices reported in the lab.

“As long as you have sunlight, you can use this device. It doesn’t have to rely on well-built infrastructure,” says Zhao. “You can use it off-grid in remote areas.”

The next step is to manufacture the aerogel at high quality in high quantities.

“Once we have the aerogel scaled up, we can think about providing the device to people who need it, such as channels like NGOs and other organisations. We can also think about using the same technology for larger-scale applications. For example, food processing plants and chemical plants, they use boilers steam generators too.”