Japan Today

Panasonic develops tubes for geothermal electricity generation, waste heat recovery


Panasonic Corp has developed innovative thermoelectric tubes especially suited for fluid heat source such as hot water and steam. The tubular shape enables direct and efficient heat transfer without additional heat exchangers, yielding high density of generated power. Panasonic's thermoelectric tube with simple, compact, and efficient features is an ideal solution for capturing unused or wasted heat from hot springs and factory.

Thermoelectric technology is the direct energy conversion from heat into electricity and has attracted much attention as a renewable energy solution. Since conventional thermoelectric generators are complicated in structure and restricted in planar shape, they are difficult to scale-up and implement. Panasonic's thermoelectric tubes solve these problems by using unconventional phenomena called transverse thermoelectric effect, which takes place in tilted multilayer made of thermally-resistive thermoelectric materials and thermally-conductive metals.

This effect makes it possible to control heat flow and electric current independently in materials, and realizes quite simple structure without complicated electric junctions and planar substrates.

The performance of power generation is strongly dependent on many parameters such as size of the tube and amount of heat source. Panasonic has developed the simulation technology to optimize the design of the thermoelectric tube in order to maximize the output electric power in accordance with surrounding conditions.

The thermoelectric tube is constructed by stacking conical rings of bismuth telluride as thermoelectric material and nickel as metal. Panasonic has developed processing technologies in fabricating conical rings of brittle thermoelectric materials and bonding rings with minimum parasitic electric and thermal losses.

The 10 cm-long fabricated thermoelectric tube using technologies introduced above can generate 1.3 W of electricity by running hot water of 90° C inside, and cold water of 10° C outside the tube. The power density corresponds to as high as 10 kW with only 1 m3 of volume. Development on system design, optimization in manufacturing and feasibility study are now under way or planned, with a view to realizing compact, efficient, and economical generators fueled by geothermal energy and waste heat in factories.

On this development, Panasonic holds 29 domestic patents and 12 overseas patents, including pending applications.

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Sounds like this could suit Japan. Maybe along the lines of hybrid vehicles, we could have buildings that generate their own electricity as they go, even using their own waste heat. It wouldn't have to be on the level that would justify a power plant, just enough for it's own use, feeding any excess back into the grid.

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Panasonic is doing good business on the ecology research front. In fact its the only company I hear about in Japan working so hard on making everything more energyfriendly.

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This is excellent. I would love to see them push more with tidal generation of electricity. Tech is there, but go Panasonic.

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This is exactly the kind of invention and new thinking that I have been asking for in comments to previous articles. That being said, I wonder if the would not be better of just heating the water in pressurized pipes and run turbines of the steam to generate electricity. Which ever works better, more power (pun intended) to them.

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That should have been: ....I wonder if they would ...

On a side note: JT, I would really like to see a possibility to edit and maybe retract comments. Guess I should just use the Preview button huh?

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In Japan existing technologies are there to phase out nuclear and gas-the politicians have not expressed much interest in implementing them! .And the question has to be asked, why are not rooftop gardens not mandatory?This would allow natural cooling in the summer Why are there not pv solar panels on the roofs of the countless apartments and houses that I see from the train on my way to work?

Why is there not a scheme to fully fund self generating electricity in Japan?

Why, why why?

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Why? Because this, like many products in Japan, are qualitatively promising but quantitatively impractical. Thermocouples have been around for a long time, but they generate only small amounts of power. This 10cm tube generates only 1.3 WATTS. You'd need 10 of them to power a single high-efficiency light bulb. And what's the environmental and monetary cost of manufacturing these?

Japan needs large-scale solutions that work, rather than 細かい details that suck human productivity for small gains. This type of tech is useful in niche field applications (powering a pump by geothermal heat, for instance), but it is not a solution for general use.

If Panasonic started making better insulated homes it would probably have more impact on long-term electrical consumption than making thermocouples.

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Iceland seems to do well from geothermal but I would concede that small scale implementation of new technologies is difficult.However, solar power, pv panels are being installed in Germany and the UK! Japan with a much sunnier climate is extremely slow to adopt new tech. In the UK (in the north) I could qualify for a 100% subsidy to cover my roof with pv panels cutting my electricity bill by 50% or more! If that is the case with the UK think what the potential is here.......

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kurisupisu said: Iceland seems to do well from geothermal

But Iceland isn't in the ring of fire. I've worked on renewable energy technologies my entire career (in the US) and support their use everywhere. But as an engineer I don't see how you can maintain the deep pipes needed for large geothermal plants, while being hit by earthquakes all the time.

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even if this can be used only on a small-scale, decentralized basis, if it is cost effective, it's great.

but can we see a little better editing of the translated text of the article???

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@Photoman333 I would suggest that as the level of geothermal energy in Japan is relaticely high near the surface in parts of Japan eg Kyushu,that it would be possible to utilise that energy right now without the need for deep pipes

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Well, it's about bloody time! If only they had done this 30 years ago Japan would be a world leader in renewable energy sources instead of an international laughing stock cos of the Fukushima debacle.

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kurisupisu said: I would suggest that as the level of geothermal energy in Japan is relaticely high near the surface in parts of Japan eg Kyushu,that it would be possible to utilise that energy right now without the need for deep pipes

Well THAT would be good. Geothermal really can work as long as you re-inject the water (otherwise you end up with a lot of caustic water).

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