

An Industrial-Sized Generator That Runs on Waste Heat, Using No Fuel - cryptoz
http://www.technologyreview.com/news/531526/an-industrial-sized-generator-that-runs-on-waste-heat-using-no-fuel

======
Animats
Their figures claim they get 2.5% more energy from a power plant with this. It
may not be worth the trouble. Attempts to recover the last few percent of
power from a heat engine result in more equipment cost per unit of power.
Steam turbines for power plants have rows of blades, each bigger than the
last. This stops when cost/benefit calculations indicate another row of blades
would be a lose.

This goes back all the way to reciprocating steam engines, where additional
cylinders could be added to use the waste steam from the previous expansion.
There were successful double-expansion and triple-expansion engines. The
economic limit turned out to be triple-expansion; while 4 and 5 stage engines
were built and tried, the additional cylinder cost was a net loss.

Little thermoelectric generators have their uses. It's useful to put one in a
gas or oil furnace to power the controls and fans. Then you still have heat
even if you lose electric power but have fuel. If these guys have a better
thermoelectric component, that idea is worth reviving. See
"[http://www.google.com/patents/US5427086"](http://www.google.com/patents/US5427086").

E = (T1-T2)/T2. That's all you can recover.

~~~
rtkwe
Like you said it comes down to how much it costs to extract that 2.5% from the
exhaust. One benefit to this over just adding more turbines is that it can be
done aftermarket as a cheaper way to provide additional capacity to the grid
without the expense of building a new or expanding plant(s).

> The first customers will probably be oil, gas, and mining companies that use
> large generators to produce power in remote areas. The generator could save
> those companies millions in fuel, Scullin says. “There aren’t many levers
> these companies can pull to reduce costs that much,” he adds.

This aligns with the cost centered evaluation too. These installations have
huge usage and transport costs relative to a normal generation station.

------
grecy
Linked for that article is "Thermoelectric Material to Hit Market Later This
Year" [0]

Which is interesting. I've been thinking about using a thermoelectric
generator in my off-grid cabin to make up for the lack of solar in the winter.
Up here in Yukon the wood stove is burning 24x7 from October to March, and you
can guarantee it's not above -10C (often -30C) outside.

I'm thinking of mounting a bunch of them near the stove for the hot side, then
running a radiator outside for the cool side. I don't think it will be too
hard to get a temperature difference of a few hundred degrees C. Hopefully
this new material will come good on it's 5-10% efficiency.

[0]
[http://www.technologyreview.com/news/528841/thermoelectric-m...](http://www.technologyreview.com/news/528841/thermoelectric-
material-to-hit-market-later-this-year/)

~~~
mabbo
It would be better to put them at the chimney output level instead, no? That
heat is definitely useless, going into the sky. But the heat at wood stove
level is useful- it's heating your cabin and cooking food.

------
beloch
Gas/Coal/Oil/etc. power plants have long captured heat from exhaust to produce
additional power. They typically run the exhaust through a heat exchanger that
heats water to run a steam turbine.

It would be interesting to learn how this method's efficiency and cost
compares for a large power plant, but it sounds like it might be practical for
small power plants where traditional methods of capturing exhaust heat are
uneconomical.

------
HCIdivision17
I would be curious to see how well the tech scales down. There are so very
many industrial processes that generate huge amounts of waste heat just to
dump it into the local environment. Power plants are the clear winner here,
but I would be curious to see if smelting and metal working industries could
benefit as well. Anyone in those fields have an idea?

~~~
NickNameNick
The problem is, most of those industrial processes need to be cooled already.
Putting any sort of energy capture in the cooling system will cost you more in
reduced efficiency elsewhere.

------
Hoffmannnn
If the key to this company is the material, and the material was developed by
(and probably licensed out by) a university, then what gives this company a
sustainable competitive advantage?

