District energy from the Willamette

[depakid]

Sometime in the next several years, Willamette River water – carried through large underground pipes in a miles-long loop – could heat and cool dozens of buildings in the yet-to-be-built North Pearl District.

The overarching idea – something called “district energy” – is hardly a futurist “pipe” dream, so to speak. It’s a very old idea, actually, updated for the eco-friendly 21st century.
...

The main questions, of course: How much would the project cost? Would it make economic sense? And who wants to pay to build it? (Hint: It could end up being the city of Portland.)

The district energy idea – in general, the idea of using a central utility plant and underground piping to heat and cool a number of buildings, rather than each building having its own heating and cooling plant – does not have to include using the Willamette River water.

That idea – flowing the water through insulated pipes and sucking usable heat or cooling from it before returning the water to the river – is the idea of Portlander John Sorenson. The water would be returned to the river at the same temperature it was originally.
...

A district energy system being built in Vancouver, British Columbia, will use a heat transfer process from the city’s piped sewer water. What is common in all systems is that, however the energy is generated, it is used to heat – or in some cases, cool – water that is then piped through the underground piping. Then heat or cooling transfer equipment at each site turns the hot or cool water into heat or air conditioning for the building.

More: http://www.portlandtribune.com/news/story.php?story_id=119032346879638600

[phantom power]

1. Makes me wonder about thermal pollution.

[depakid]

2. I'm curious about how that would work, too

but supposedly, according to the article- the process is heat neutral with respect to river water entering and leaving the system.

[NNadir]

3. I recall calcuating at one time that world district heating provided about 3 or 4 exajoules of

energy that would otherwise be produced by dangerous fossil fuels.

District heating is usually a very, very good idea.

Of course, around the same time that the terrible earthquake in Japan caused the radiation release that wiped out Japan forever, there was a steam explosion in downtown New York that released asbestos and killed a pedestrian.

As I recall, once everyone found out that it wasn't a terrorist attack, but merely a corroded pipe, the world decided it couldn't care less.

New York City has long had district heating. The first such system was set up by Thomas Edison's people. Many modern power plants in the East are set up for this. The new nuclear reactor at Cernovoda in Romania is fitted for this purpose. It came on line last year, IIRC.

[NNadir]

4. I went back and checked.

I did the calculation for a post at another website.

The actual amount for the world's largest district heating systems was 0.87 exajoules.

http://www.energy.rochester.edu/dh/largest.htm

Still this is more energy than is produced by all the world's solar PV power stations.

[depakid]

5. The top 5 producers are all in former eastern block nations

Interesting.

[NNadir]

6. Another interesting effect is that people who live with district heat systems

tend to be more wasteful with energy, at least in terms of insulation and things like that.

On some level it's hard to argue that they're being wasteful in the sense that they are capturing energy that would otherwise be dumped into the environment. On the other hand, shipping that hot water involves a certain amount of pumping and things like that.

The matter is covered, if you have access to a technical library there is an interesting paper that convers this topic: Energy 32 (2007) 1769–1780.

Here is an excerpt from that paper that touches on the point:

Buildings that use district hot water or packaged units for heating purposes use energy more intensely than those using conventional furnaces. Compared to fuel/heating oil, the use of electricity or liquid petroleum gas or propane leads to a lower intensity of energy use, while the use of natural gas increases energy use intensity. Some of these differences may be due to differences in fuel prices, allowing higher comfort level settings when less expensive fuels are used. Unfortunately, building specific energy cost data were not collected in the survey.

I wrote a little more extensively on this paper elsewhere.

When one is young and niave, one has all sorts of environmental fantasies and ideas and as one grows older, wiser, and more informed, some of these ideas drop away once you realize that other people - truly original ideas are rarer than you think when you're a kid - tried them and they didn't work quite as well as expected. This is probably why I'm such a cynic about solar PV electricity and it's oft advertised promise from its advocates that it can "do everything," when actually it can do very little.

Whatever. I remember talking with the father of my seventeen year old girlfriend about the subject of cogeneration when she was the oldest girl I had ever dated. I was all of nineteen myself.

Of all my childish energy ideas, the idea of cogeneration is the one that has eroded the least. I still think it is one of the most readily available and most under utilized sensible energy strategies there is. And yes, I would favor building nuclear power plants in downtown Manhattan to exploit this kind of opportunity.

[IDemo]

7. I'm wondering what becomes of the dissolved oxygen concentration of the water

Warmer water as a rule contains less oxygen, which can become a significant factor in fish deaths. I don't know how much, if any, difference in oxygen content between water output vs water returned to river would occur in such a system, but it might be worth a look.

on edit - It appears that oxygen is the enemy in DH systems due to its corrosive nature. Suitable aeration of the return flow should solve oxygen depletion issues for the fish population.

[razzleberry]

8. Combined-heat-and-power, not a new invention .n/t.