Heat accumulator

Piwoslaw · 12-22-09, 05:31 AM

I'd like to share something I recently found out about how my local power plant uses a new method for raising its efficiency, thereby reducing emissions. But first some background.

Most of the power plants in my climate zone are geared towards producing heat, electricity is a by-product. Of the four power plants in Warsaw only two generate electricity, the other two are shut off at the end of each heating season. The heat feeds the city's warm water network, providing heating for most of the high-rise apartment buildings during the winter, and warm water in the faucets year round. This is more efficient than local, distributed heating. One of the downsides is that it's very hard to adjust production when demand changes hour-to-hour. Most of the electricity is needed in the morning and evening, with a dip at mid-day and a minimum at night. On the other hand, heat production is needed most during the night. Some power plants have extra furnaces that get fired up when demand goes up, but this takes around 3 hours and wastes lots of fuel (almost all power plants here are coal fired, but more are building biomass furnaces). When generating heat at night, the power plant can generate lots of electricity at almost no cost, while during the day the situation is reversed.

About 1-2 years ago the largest power plant in Warsaw decided to add a heat accumulator, already in use at many Skandinavian plants. It's basically a huge thermos which gets warmed up with waste heat during the day, relieving the night load. Or it can be heated at night the help generate electricity in the day. This is a VERY simple setup: just a 47m-high cylinder, 30m in diameter, holding over 30.000 cubic meters (30mln liters) of water. No extra machinery or heat exchangers, just an extra valve. Its heat capacity is 1300MW(thermal). The cost was about US$17mln. I can't find much info on it, nothing on how much it actually saves, but I did find out from an insider that the power plant is very happy with it. So much so that other plants are planning on building something similar.

On a smaller scale, I've read that water-based household heating systems sometimes employ an insulated buffer tank to collect heat when it's available (solar) or cheap (night tariff). I belive that the rule of thumb is around twice the volume of water in the pipes and radiators of the house.

On an even smaller scale, the genII Prius has a thermos for storing engine heat.

12-22-09, 05:31 AM	#1
Piwoslaw Super Moderator Join Date: May 2009 Location: Warsaw, Poland Posts: 964 Thanks: 189 Thanked 111 Times in 87 Posts	Heat accumulator I'd like to share something I recently found out about how my local power plant uses a new method for raising its efficiency, thereby reducing emissions. But first some background. Most of the power plants in my climate zone are geared towards producing heat, electricity is a by-product. Of the four power plants in Warsaw only two generate electricity, the other two are shut off at the end of each heating season. The heat feeds the city's warm water network, providing heating for most of the high-rise apartment buildings during the winter, and warm water in the faucets year round. This is more efficient than local, distributed heating. One of the downsides is that it's very hard to adjust production when demand changes hour-to-hour. Most of the electricity is needed in the morning and evening, with a dip at mid-day and a minimum at night. On the other hand, heat production is needed most during the night. Some power plants have extra furnaces that get fired up when demand goes up, but this takes around 3 hours and wastes lots of fuel (almost all power plants here are coal fired, but more are building biomass furnaces). When generating heat at night, the power plant can generate lots of electricity at almost no cost, while during the day the situation is reversed. About 1-2 years ago the largest power plant in Warsaw decided to add a heat accumulator, already in use at many Skandinavian plants. It's basically a huge thermos which gets warmed up with waste heat during the day, relieving the night load. Or it can be heated at night the help generate electricity in the day. This is a VERY simple setup: just a 47m-high cylinder, 30m in diameter, holding over 30.000 cubic meters (30mln liters) of water. No extra machinery or heat exchangers, just an extra valve. Its heat capacity is 1300MW(thermal). The cost was about US$17mln. I can't find much info on it, nothing on how much it actually saves, but I did find out from an insider that the power plant is very happy with it. So much so that other plants are planning on building something similar. On a smaller scale, I've read that water-based household heating systems sometimes employ an insulated buffer tank to collect heat when it's available (solar) or cheap (night tariff). I belive that the rule of thumb is around twice the volume of water in the pipes and radiators of the house. On an even smaller scale, the genII Prius has a thermos for storing engine heat. Last edited by Piwoslaw; 01-14-11 at 10:12 AM..