Heating towns using cold water

I can't really give you a good explanation (just Google "heat pump" — there's a lot of info out there), but they basically work like an air conditioner or refrigerator in reverse (ie. compression of a gas "creates" heat). Though, actually, I think heat pumps can create heat in the winter and cool in the summer, so it's not even really "in reverse."

There are also heat pump hot water heaters that use the ambient temperature of a house to heat water. Pretty cool.

Really interesting. Would it work in Duluth? Is electricity economical enough to support the system? Somebody write to Minnesota Power and ask.

The only way this would be feasible in Duluth is if the steam plant could be retrofitted. It is close to the lake, so that is helpful.

Often something that holds back the use of heat pumps is the high capital cost.  For your house, an air-to-air heat pump can cost about 5x what a NG/LP furnace does.   But it does usually pay back in cost savings over time.  And provides air condition as well.  In addition around here, the air temp gets cold enough you need a furnace back up anyways, so additional capital investment.

@KARASU, the "in reverse" for heating your home in the winter is you are effectively air conditioning the outside air by removing some of its heat and transferring it inside.  The "in reverse" for cooling your home in the summer is effectively heating the outside air by transferring inside heat to the outside.

Heating will surely be one of the main challenges for a sustainable future. This seems hopeful.

The only way this would be feasible in Duluth is if the steam plant could be retrofitted.

Not sure if it is the same system as in the article, but Don Ness did mention that upgrading the steam plant to a closed water system instead of coal is on the radar.

http://www.duluthsteam.com/whats-happening/

@K.Praslowicz, the closed water system would still be coal fired, and just circulate hot water instead of steam.  The company that manages the steam plant also got a big grant to co-fire wood biomass with the coal.

It might work here. This seems to be in essence a city-sized geothermal system using the lake as the heat source. They say their water is 8c, or 46f, ours bottoms out at about 2c Jan-Mar. They also say they need to boil the ammonia at 2c, which is pretty close to our water temp. Maybe with a higher pressure it could work for us.

The advantage of the heat pump is you can get two times the heat from pumping as you can using the energy to do the heating directly.    The downside is you have to use electricity for it rather than burning cheaper stuff.

$52 million in steam plant investment can save 8,000 cars worth of CO2, keep 80 million gallons of water away from the sewer plant,  and reduce coal consumption by 40 percent per year.

Duluth Steam Master Plan

A big part of this is the biomass via sawdust or wood chips. Virginia and Hibbing do this for their municipal steam/electric plan, which get 25 percent or better of their biomass from farmed poplars.