District heating has been big in the Big Apple since the eighties... that is, the 1880's. The whole island of Manhattan is cris-crossed with steam pipes which occasionally make the news.
On a whim, I tried to find the price of steam in Manhattan. I was somewhat surprised when I found it. Steam goes for about $31 per thousand pounds
, and each pound carries about 1200 BTU of energy. This comes to roughly $26 per million BTU, or a bit under $25/GJ.
NuScale doesn't give the output conditions of the steam from its reactor, but it does give the turbine throttle pressure: 475 psia
. This yields a minimum temperature of ~462°F (239 C). ConEd distributes steam at about 165 PSIG and 358°F
(which has to be a typo, as this temperature/pressure is compressed water; real temperatures would be slightly superheated at 375°F or more), so if the NuScale was used for district heating there's some room for a topping cycle to drop the steam pressure.
The NuScale boiler inlet water spec is 300°F; assume 500 psia: h = 627.7 kJ/kg. Steam at 475 psia/275°C (reasonable PWR SG outlet conditions) has h = 2946.1 kJ/kg, Δh = +2318.4 kJ/kg. Dropping this to 180 psia/saturation yields h = 2784.9 kJ/kg. (I did not check the entropy to see if the steam would still be superheated.) Δh = -161.2 kJ/kg. Roughly 6.9% of the input heat is convertible to work even if high-pressure steam is tapped off for district heating.
6.9% of 160 MW(t) is 11.1 MW, which is more than enough to cover the NuScale house loads of about 2.5 MW per unit.
Assuming up to 145 MW(t) of steam output, this comes to 522 GJ/hr with a value in excess of $12,500 per hour. If this can be sold at 30% capacity factor, revenue from heat sales would be on the order of $33 million/year. A NuScale unit selling for $6/W(e) installed would cost $285 million; $33 million/year in heat sales alone would be a greater than 11%/year return on investment not including electric output.
If New York could be gotten off its paranoia over nuclear power, this could be YUGE.
Labels: cogeneration, district heating