Waste heat as heat source [was Re: Energy 101 [was Re: OT Hydrogen economy, not?]} - Page 3

 On Jul 23, 2:31 pm, phil-news-nos...@ipal.net wrote:


Part of downtown Concord, NH used to be heated by steam from a central
plant. When a pipe broke in winter everyone lost heat and closed until
it was fixed. I suppose modern, better-insulated buildings could
manage on the electric supplement to the heat pump.

  On 23 Jul 2008 18:31:23 GMT, phil-news-nospam@ipal.net wrote:



Oh, I guess that if a Stealth Bomber launched an attack on the switchyard....

There isn't much of anything short of a widespread disaster that could take a
unit down.  There have been a few instances where a cascading series of
failures has taken a plant "black" but they're so rare that they make the
trade press.


Physical separation between trains are deemed sufficient to protect against
any single failure taking out all sources of power.  That holds for nuclear as
well as fossil plants.

It doesn't look like it from the outside but the various trains are grouped in
logical layout with much space between them.

In all such discussions, though, one has to zoom back out to the big picture.
If the plant happens to go down for, say, a week once every generation or two
then is the benefit of very inexpensive energy the rest of the time worth the
slight inconvenience of having to heat with resistance or alternative heat?  I
think that most folks would say so.



This concept isn't district heating.  I haven't made up a descriptive name for
it but perhaps "district heat sourcing" or something similar.  People
participating in this system would have some form of heat already.  Or in the
case of new developments, the comfort heat would be standard resistance backed
water-sourced heat pumps.  

It wouldn't be like in a district hot water or steam heating situation where
if the plant went down, there would be no planned alternative source of heat.
I've been curious to know what people who live in district heating cities do
when the steam fails.  Probably space heaters.

It might be in the beginning for existing communities.  But suppose a
community were planned around a power plant the same way aviation communities
are built around a common runway and marine communities are built around a
canal.

Once the word got out about how much cheaper it was to heat and cool, some
other community, perhaps a low density one where infrastructure would be easy
to build, would give it a shot.  More positive results would spur more
positive interest.

No new concept like this gains widespread adoption overnight.  Look how long
it took for electrification to become widespread.  Edison built his NYC
lighting plant in the 1800s but it was many decades before electricity was
common.  Heck, 5 miles up the road from where I live, electricity didn't come
until the 70s.

Or for that matter, look how long it took the Internet to become common.


Condensation is something to be dealt with but it's a known problem and the
solutions are long since well-engineered away.  Proper pipe slope and steam
traps at the low spots handle removing the condensation from steam pipes and
conducting it either to waste or to the condensate return pipe, depending on
architecture.  The major concern is the waste of heat represented by the
condensation.


Water is hugely less efficient, because it has to be pumped, because there is
much more drag on flowing water than gas and last but most important, water
transfers heat only by simple specific heat while steam transfers heat by heat
of vaporization and condensation.  Steam is 60-something times more effective
in transferring heat than water.  I don't recall the number but it's easy to
look up.  The specific heat of water is 1 BTU/pound.  The heat of vaporization
of water is sixty-something BTU/pound.  A little bit of steam goes a long way
:-)

John

--
John De Armond
See my website for my current email address
http://www.neon-john.com
http://www.johndearmond.com  <-- best little blog on the net!
Tellico Plains, Occupied TN
You can't turn [MS] shovelware into reliable software by patching it a whole
lot. -Marcus Ranum

 Maybe the first place to do this would be one of those planned
communities, like the Sun City retirement communities.  I don't know if
they go so far as to do their own power generation but putting your idea
into the infrastructure at the beginning would definitely be the
cheapest way and I think they pretty highly control all the necessary
infrastructure choices so the demand would be guaranteed.  Then they
could use the cheaper utilities cost as a selling point.

--
Regards,
Carl Ijames  carl dott ijames aat verizon dott net
(remove nospm or make the obvious changes before replying)

 
| The answer is "it depends but probably yes".  A couple of different
| situations.  One, the plant is built with numerous smaller units instead of
| one or two very large ones.  That's a fairly common practice with coal-fired
| plants.  TVA's Widow's Creek, for example has around 13 units (I'm unsure of
| the number because they were talking about decommissioning the oldest one(s))
| units on one site.  One or more are always down for maintenance but the plant
| always makes power and thus warm condenser water.
|
| Routine outages can be planned for mild weather.  Emergency outages are not
| likely to affect both/all units on a site.
|
| In the event all units are down, river water can still be diverted into the
| canal system.  39 degree water (where water is the densest and thus the
| typical temperature underneath ice) still contains a LOT more heat than, say,
| 20 degree air.  Or -20 deg air where a heat pump would not function at all.

Would this be "free heat" or would the users have to pay for it somehow?

If it had to be paid for, there might not be as many takers.  That and the cost
of the equipment to measure the energy actually taken.

If it is free heat, who pays to build the infrastructure?  I'm guessing that
to the power plant that wants to just get rid of the heat, the existing way
is the least cost way.

100+ years ago when we didn't have the comforts of home central heat like we
do today, taking off excess heat that somehow was present and distributing it
would be such a good idea everyone would approve.  Today we have to consider
it not as a comfort issue, but as an energy savings issue, which is partly
financial, partly environmental, and to a limited degree partly international
political where ones heat source could be repurposed to reduce oil importation.
Getting they money for it might be the show-stopper (as sad as that is given
our complex energy situation).

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| Phil Howard KA9WGN (email for humans: first name in lower case at ipal.net) |

 
I will be poluting the Earth and contributing to global warming. I have a lot of
wood trees out back which I will be amputating over the next years. I am going
to put the coal/wood stove in the garage this year. next year I will add a stove
to the existing house chimey the last owners installed. I was looking at that
Harbor Freight
stove last winter. We used to buy stoves at Montgomery Wards. Those are long
gone as is the old house.

greg