Small Fujitsu Device Harvests Both Solar and Thermal Energy

destinyland writes "Fujitsu has built a device that can simultaneously harvest energy from either light or heat. They've reduced production costs by using the same cheap organic substrate for both conversion processes, while also doubling the potential amount of energy that can be collected. 'Previously, dual harvesting of energy could only be done by combining two different devices,' the article notes — and the device's solar converter can even draw energy from indoor lighting as well as direct sunlight. Fujitsu predicts the device will be especially useful for powering medical sensors, since the flexible substrate can be included in monitors which conform to the shape of the human body."

Comments

makes sense

[wizardforce]

From the article it seems they're using both the seebeck effect and photovoltaic cells to do this with two different semiconductor materials. Basically it's a type of solid state solar thermal power generation.

Re:makes sense

[Doc Ruby]

The Seebeck effect is pretty inefficient, but it does produce electricity from heat which is better than no electricity. If the PV is maxxed but still hot, maybe the extra costs of the material justify the little extra bit of electricity it can add with the Seeback effect. Until we see actual efficiency measurements of an actual device, this announced device could be a waste of time. It always bothers me when a report doesn't mention the efficiency of the power generation or conversion, because it's never high enough to ignore, and is practically always the make/break factor in what's announced.

Re:makes sense

[skids]

"Most solar panels decreases in efficiency warmer they are"

Most solar panels are still Si based. Some thin-film chemistries actually increase in efficiency when they get hotter, however.

Stanford's looking at something roughly similar.

Sounds like a plot to a horror movie

[Anonymous Coward]

"It's escaped from the lab, and is now harvesting the energy of the nearby town including its residents. If it continues at its current rate, we're looking at a worldwide extinction event in a matter of days."

Re:Sounds like a plot to a horror movie

[gestalt_n_pepper]

You see, this is why I always buy Sony.

Re:Huh?

[Doc Ruby]

Radiant heat is light, infrared. The heat in materials that is transferred conductively, like when you touch it or when a house warms surrounding outside air, is not light.

Bad summary

[Solandri]

If it can simultaneously harvest energy from two sources, then it's harvesting from light and heat. If it can only harvest from light or heat, it can't do it simultaneously. If you RTFA, you see that the latter is correct, and so the word "simultaneously" does not belong in the summary.

Along with the organic material that works as a generator from both light and heat, Fujitsu also used two different semiconductor materials so that the electrical circuits could could change from one mode to the other. Using an N-Type semiconductor, harvests energy from light. Changing to the P-Type semiconductor, harvest energy from heat.

Re:How can it do both?

[skids]

You'll note the series wiring is taking off two opposite sides P-type segments, whereas the parallel wiring is connected to both N and P type.

The parallel diagram is deficient in that it should really show the parallel wiring between P-type segments the same way the serial diagram does, even though position on the section doesn't matter as much in the light harvesting. It would be clearer that they are the very same wire.

It looks like the best place to think of as the "ground" (too tired to deal with plusses and minuses right now) is the left side of the P-type wire, and consider that the voltage produced by the thermoelectric effect is likely, even after being chained in series, smaller than the photovoltaic differential (though maybe higher current.)

It's probable that the parallel "wire" on the N-type also connects at points optimal for compensating for a simultaneous thermoelectric effect.

Re:I still think my idea is better

[Doc Ruby]

Coat everything that's attached to the grid with PV material, especially things that already have an inverter. Reusing existing infrastructure can cut starting costs by half or more, which makes PV usually cheaper than the other grid generators. Every little bit counts, and the more distributed the solar receivers the more likely somewhere is getting sunlight at any given time. PV on as many roofs as possible not only increases generation, but distributes it around the grid, reducing substantial transmission losses and increasing efficiency. The generating plants for the top demand, that come on and off intermittently instead of running constantly, will be called on less, which is a very big savings, including not building as many new ones.

Re:I still think my idea is better

[Banquo]

Actually if it were attached to a system that could determine which source was better at the time, then switch I think just putting a strip of this down the emergency lanes/inside lanes of all the major roadways in the US would probably provide some insane power. During the day gather sunlight and then in the hours and hours after that the roads maintain heat, gather ambient heat then.

If you could actually "pave" the roads with a photovoltaic material THEN you're talking serious energy. Major Highways see sunlight through most of the day and have a combined 4,042,778 miles of interstate highways,...that's a really good place to start.

Of course there are new and proven building materials for highways right now that won't get approved because their repair cycle is so long it puts people out of work on a massive scale, so whoever builds this new energy tapping roadway better plan some obsolescence into it or it will never fly. (Yay for government efficiency!)