Ice Energy's Cool Add-On Ups AC Efficiency 30%.
by John Laumer, Philadelphia on 07.28.05
Instead of "look...a runaway bride", TreeHugger writers go more for "look..homeowners can save hundreds each month". We're that way because we know our readers love commonsense technologies like bicycles as much as they do complex new stuff like hybrid cars. Ice Energy's debut product, which upgrades a conventional air conditioner by using night-made ice to shave the expensive peak daytime AC load, certainly seems to be the real "Big Green" deal. They claim up to a 95% day-time air conditioning efficiency boost, and, according to a DOE review, a 30% overall energy savings. This should give serious pause to the other Federal agencies who think the only practical route forward is to "drill our way out" of Peak Oil and ignore the risk of climate change.
Right now the "Ice Bear" commercial unit (pictured) is getting some field testing in "brown out central" municipal buldings. They already make a unit for McMansions (4,000 ft2+ homes) but are reported to be working on a smaller one for average residences. That's striking distance from a lot of TreeHuggers we think.
A typical AC compressor unit has a design life around 15 years or more; so, saving 30% of operating costs every year should result in a decent paypack. The Ice Energy website has cool schematics and install pics which TreeHugger recommends you check out before commenting.
From the Victorville CA Daily Press of July 26th. "Officials at Victorville City Hall are running one of Ice Energy's cooling units as part of a free demonstration project. After about three months, the city will look at the energy savings and may order three to four units for city buildings, said Jon Gargan, Victorville's director of community services"..."The city of Anaheim is also participating in the pilot project".
"The Ice Energy device includes a storage unit containing water is attached to the air conditioner. During the night, when the air conditioner is working most efficiently, the water is frozen. Then during the day, that ice provides a cool environment for the air conditioner to transfer heat from the building, increasing the efficiency of the air conditioner during hot hours, when demand for electricity peaks".
Look...over there...there's more good stuff just around the corner.
I thought some of you might be interested in this, and somewhat relevant to the current article:
My wife noted (see URL below) this morning that she can use the dripping water from our air conditioner to water the plants. Not much water saved, but every little bit counts, right?
Another benifit of this technology is the reduction in peak electrical demands. Electrical infastructure needs to be built to handle the maximum demand (usually occuring around 2-4 PM). Usually, natural gas and oil generators are brought online to provide this power but this approch would level out demand somewhat. I believe the John's Hopkins Physics building has been using this technique to reduce their electrical demand for decades now.
It is also worth noting that transmission loss is highest at peak current flow. For this reason (time) spreading out demand has other benefits.
Hi, I liked this post. Thanks -
Chris, www.goodcommonsense.net
Does this technique actually reduce electricity consumption, or just move that consumption to non-peak hours?
BTW: The Hewlett Foundation Building also uses this approach.
====answer to EY comment follows =====
Caveat: the following answers are theoretical, but easily verified by your utility or by discussions with an electrical engineer. Invest no money based on this information until you have corroborated it with other experts.
OK then. By moving consumption to nighttime, the owner's Air Conditioning compressor operates at the low end of its peformance range for a greater part of the 24 hour day. At the low end of its duty cycle is where it its most efficient. Also, by reducing the daytime consumption of electricity (users get much of their daytime 'cold' from the ice block instead of the AC compressor's work), utiltiies do not have to invest as much in peaking power plants and are less likely to have to run any plant close to the peak of its operating capacity. IN cases where peaking plants are old coal fired ones or oil burners operating without best available emission controls, this is especially important. Said another way, a plant operating at peak of generating capacity may operate less efficiently than the level for which is was optimally designed, and pollution controls also become less effective per unit of output than they are at lower levels of generaton. Hence, more emissions result per unit of useful cooling work done at the customer end. Fnally, and as a commenter pointed out, electrical transmission lines heat up qutie a bit when consumption is peaking. THe hotter they get, the greater the amount of "line loss" per unit of consumption. Line losses are variously reported in the 3 to 9% range (depends on who you talk to and how old the lines are, etc.). When its really hot out and the lines are buzzing to make air conditioners work under constant load, lost voltage is on the high end of whatever range is appropriate. Sidebar: It would seem that the Enron practice of moving electricity hither and yon was especially wasteful bcause it was done when demand was highest.
THe value of "load spreading" with this technolgy then, if done extensively enough to make a grid-wide difference, is that those line losses are reduced, keeping them to the low end of the expected range. Hope this theoretical discussion is helpful. Others: please jump in if you have better info!
You actually use less electricity.
A/C efficiency depends on the difference in temperature between the interior air being cooled, and the outside air into which you have to dump the heat being moved from the interior. The hotter the outside air passing over the radiator, the harder the system has to work to cool the radiator.
This system works efficiently at night when the night air is cool, and uses the ice to cool off the radiator during the day, and make heat transfer more efficient. Of course, if you have time-of-day metering, then you save even more money by reducing daytime usage.
You actually use less electricity.
A/C efficiency depends on the difference in temperature between the interior air being cooled, and the outside air into which you have to dump the heat being moved from the interior. The hotter the outside air passing over the radiator, the harder the system has to work to cool the radiator.
This system works efficiently at night when the night air is cool, and uses the ice to cool off the radiator during the day, and make heat transfer more efficient. Of course, if you have time-of-day metering, then you save even more money by reducing daytime usage.