Wednesday, April 4, 2012

Scientists develop ultra-thin solar cells

Today, Austrian and Japanese scientists have unveiled solar cells thinner than a thread of spider silk. These cells are still flexible enough to be wrapped around a single human hair. In the article on Physorg, Sekitani, from the University of Tokyo and one of the lead researchers, said the team hoped to increase the rate at which the device converts sunlight into electricity and put it to practical use in around five years.

So, what impact does this have on solar energy powered cars? Couldn't a car store the energy saved all day to charge the battery for later use?

Ignoring clouds, the daily average irradiance for the Earth is approximately 250 W/m2 . A Toyota Camry is 4.805m long and 1.820m wide, for a total top area of ~8.75m2 . That means every hour in the sun absorbs 2188W. Eight hours in the sun would get you 17,504 Wh.

But we have to take inefficiency in solar tech into account, which is currently around 10-20% efficient for most commercially available types. So we're only getting at most 3500Wh or 3.5kWh. Also that assumes no clouds and direct overhead sunlight, which is not often available, but for the purpose of the calculation we'll comply with. The Tesla Model S gets about 3.5 miles/kWh from it's battery back.

So covering your entire car with solar cells and leaving it in the sun for an entire day would get you at most 12.25 miles, but probably a lot less as not all the cells would be lit at the same time, the sun wouldn't be directly overhead, and there could be inclement weather, etc.

Now we just need to get the battery tech up to spec with the solar cell tech. It's no accident that the Oil & Gas giants have been scooping up patents to improved battery technology for years now. E.g. Chevron owning the large format NiMH patents. The truth is that while there is lots of anticompetitive and borderline illegal behavior in the industry. After all, it's a fiercely competitive industry so not unexpected. However, generally things are improving.

Plenty of technology has been developed over the last 10 years that is well outside the grasp of the Oil conglomerates and the $/kWh (cost per kilowatt hour) of renewables is steadily declining as the non-renewables costs are steadily increasing. Renewables will probably reach price parity with non-renewables for large-scale energy generation in the next 5 years or so and forward thinking countries like Canada, Germany, Denmark, etc... are certainly speeding up the process with their generous renewables subsidies too. So fret not, renewables are here to stay.

No comments:

Post a Comment