Energy storage options are interesting and there are some new tax credits for them. But it is a big expenditure and has efficiency losses. When you consider that peak prices are only 2x off peak when you don't consider the demand charge it becomes hard to justify the large upfront costs. Especially when they might not be able to significantly reduce the demand charge.
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Saving Money With Pre-Cooling
- Thread starter ano
- Start date
apostolakisl
Senior Member
az1324 said:@Lou - it is the time that is continual not the energy usage. Energy usage is the sum total during the continual 60 min period.
OK, that makes sense. In fact, that would be the same number as average KW power usage during the hour.
Total KWH energy used in one hour = average kw power usage during one hour times 1 hour
The only question now is whether it is a rolling hour or a pre-defined hour.
EDIT:
Ironically, I just toady got a letter for my office from Austin Energy that I am being considered for peak demand rate structure based on a sample measurement they took last May (one month before I bought, gutted and remodeled the office with high efficiency stuff.) They bill on a 15 minute peak demand basis. Nowhere on Austin Energy's webisite could I find anything more than them saying "15 minute peak demand" to define it. But based on this article, it would appear that the meter figures the average of the previous 15 minutes, every 15 minutes, and displays that number if it is higher than the number already displayed. Then it gets reset to 0 every month.
http://www.think-energy.net/KWvsKWH.htm
You think so? I can't imagine its one of their top concerns. Besides, I can't really see what laws you are breaking.az1324 said:I'm sure they have algorithms in place to detect things such as one house that uses all its power during the day next to a house that uses all its power at night.
You could do that, but you would need LOTS of batteries for that. It seems like a much better way would be to store thermal energy with water. Get a big insulated tank of water. At night, cool the water, and when the rates go up, use that cooled water to cool your house. Its not a stretch to use the water from your swimming pool for this. It just might be rather cold if you want to take a dip in the morning. :unsure:Work2Play said:What about a big bank of batteries? Charge them during off-peak, then cutover to them during peak. Toss some solar on the roof to help slow drainage and reduce the number of batteries required.
Or for something more compact use a phase change material.ano said:It seems like a much better way would be to store thermal energy with water. Get a big insulated tank of water. At night, cool the water, and when the rates go up, use that cooled water to cool your house.
I don't know the cost of these
http://www.troxtechnik.com/xpool/download/en/technical_documents/air_water_systems/S_PCM_EN_1.pdf
Probably too expensive for home use but I would think someone could use the same principle to come up with a DIY solution that's fairly cheap.
Here is some more info I found
Buildings and clothes could melt to save energy
Phase-change materials that freeze at around room temperature could revolutionise energy storage, cooling things that are too hot and warming them later on
THE sun has risen, and a brand new building on the University of Washington's campus in Seattle is about to melt.
It is no design flaw: encapsulated within the walls and ceiling panels is a gel that solidifies at night and melts with the warmth of the day. Known as a phase change material (PCM), the gel will help reduce the amount of energy needed to cool office space in the building - scheduled to house the molecular engineering department when completed this month - by a whopping 98 per cent.
PCMs don't have to be as high-tech as this, of course. We have been using ice, a phase change material that melts at 0 °C, to keep things cool for thousands of years. But advances in materials science and rising energy costs are now driving the development of PCMs that work at different temperatures to help people and goods stay cool or warm, or to store energy.
PCMs are attractive energy-savers because of their ability to absorb or release massive amounts of energy while maintaining a near-constant temperature. "To melt ice takes the same amount of energy as would be required to warm an equal volume of water by 82 °C," says Jan Kosny of the Fraunhofer Center for Sustainable Energy Systems in Cambridge, Massachusetts, who began to explore the potential of PCMs three decades ago by looking at beeswax as a way to store heat from the sun. The reason PCMs are so useful is because energy is needed to break the molecular bonds between atoms when a substance melts, and is released when bonds are formed as it solidifies.
The "bioPCM" gel in the university building, derived from vegetable oils, will be "charged" each night when windows automatically open to flush the building with cold outdoor air. The solid gel then absorbs heat as it melts the next day. The idea is the same as using thick concrete or adobe walls, which reduce indoor temperature fluctuations, but only a fraction of the material is required. "Our bioPCM is 1.25 centimetres thick yet it acts like the thermal mass of 25 centimetres of concrete," says Peter Horwath, founder of Phase Change Energy Solutions, based in Asheboro, North Carolina.
A recent report by technology research firm Lux Research predicts the use of phase change materials in buildings will grow from near zero today to $130 million in annual sales by 2020.
Buildings and clothes could melt to save energy
- 05 January 2012 by Phil McKenna
- Magazine issue 2846. Subscribe and save
- For similar stories, visit the Energy and Fuels Topic Guide
Phase-change materials that freeze at around room temperature could revolutionise energy storage, cooling things that are too hot and warming them later on
THE sun has risen, and a brand new building on the University of Washington's campus in Seattle is about to melt.
It is no design flaw: encapsulated within the walls and ceiling panels is a gel that solidifies at night and melts with the warmth of the day. Known as a phase change material (PCM), the gel will help reduce the amount of energy needed to cool office space in the building - scheduled to house the molecular engineering department when completed this month - by a whopping 98 per cent.
PCMs don't have to be as high-tech as this, of course. We have been using ice, a phase change material that melts at 0 °C, to keep things cool for thousands of years. But advances in materials science and rising energy costs are now driving the development of PCMs that work at different temperatures to help people and goods stay cool or warm, or to store energy.
PCMs are attractive energy-savers because of their ability to absorb or release massive amounts of energy while maintaining a near-constant temperature. "To melt ice takes the same amount of energy as would be required to warm an equal volume of water by 82 °C," says Jan Kosny of the Fraunhofer Center for Sustainable Energy Systems in Cambridge, Massachusetts, who began to explore the potential of PCMs three decades ago by looking at beeswax as a way to store heat from the sun. The reason PCMs are so useful is because energy is needed to break the molecular bonds between atoms when a substance melts, and is released when bonds are formed as it solidifies.
The "bioPCM" gel in the university building, derived from vegetable oils, will be "charged" each night when windows automatically open to flush the building with cold outdoor air. The solid gel then absorbs heat as it melts the next day. The idea is the same as using thick concrete or adobe walls, which reduce indoor temperature fluctuations, but only a fraction of the material is required. "Our bioPCM is 1.25 centimetres thick yet it acts like the thermal mass of 25 centimetres of concrete," says Peter Horwath, founder of Phase Change Energy Solutions, based in Asheboro, North Carolina.
A recent report by technology research firm Lux Research predicts the use of phase change materials in buildings will grow from near zero today to $130 million in annual sales by 2020.
apostolakisl
Senior Member
The concept of phase change materials is very similar to thermal mass. It takes (or gives up) a lot of heat to change state, and while it is changing state, the temp holds steady. So at that temp, it has huge thermal mass provided it is starting off as a solid during a time of excess heat, and as a liquid during times of lack of heat. That requires days and nights that go significantly above temp and below temp. Like in the desert.
Well it would be rather trivial and I'm sure its against the TOS. Plus they may have similar algorithms to detect things like grow houses and other anomalies.ano said:You think so? I can't imagine its one of their top concerns. Besides, I can't really see what laws you are breaking.
You could do that, but you would need LOTS of batteries for that. It seems like a much better way would be to store thermal energy with water. Get a big insulated tank of water. At night, cool the water, and when the rates go up, use that cooled water to cool your house. Its not a stretch to use the water from your swimming pool for this. It just might be rather cold if you want to take a dip in the morning. :unsure:
Pool water has to be cooled at night just to keep it near 80. It is not uncommon for it to be 100+ after midnight. So excavation is going to be necessary for any effective thermal transfer systems.
apostolakisl
Senior Member
az1324 said:Well it would be rather trivial and I'm sure its against the TOS. Plus they may have similar algorithms to detect things like grow houses and other anomalies.
Pool water has to be cooled at night just to keep it near 80. It is not uncommon for it to be 100+ after midnight. So excavation is going to be necessary for any effective thermal transfer systems.
Pool water around here gets into the mid and even upper 90's during the summer if you just let it sit there. You have to turn the water fall on at night to get some increased surface area and evaporative cooling to get it below 90. . . if your lucky.
I agree, you would need to dig a deep hole or have a closed top fully insulated gigantic holding tank to store the chilled water in these hot types of climates. It would bet the cost would go well over 10 grand.
az1324 said:Well it would be rather trivial and I'm sure its against the TOS. Plus they may have similar algorithms to detect things like grow houses and other anomalies.
Against the TOS? I really doubt it. While they may have algorithms to detect unusual patterns like grow houses the rates are higher during the day because it stresses their distribution network and costs them to increase capacity. At off peak hours the rates are lower. Unless you are a huge user like an aluminum smelter the power company doesn't tell you when you can use power. They just have different rates for different times, peak loads, etc.
They are very smart for NOT doing that. Not only would that be an invasion of privacy, but legal evidence collected that way would be thrown out without a search warrant.az1324 said:Well it would be rather trivial and I'm sure its against the TOS. Plus they may have similar algorithms to detect things like grow houses and other anomalies.
O.K. Your pool rises in temp 20 degrees in a day, and gets over 100 degrees? In the last 2 months it has gone up in temp maybe 4 degrees. You must have a REALLY REALLY small pool.az1324 said:Pool water has to be cooled at night just to keep it near 80. It is not uncommon for it to be 100+ after midnight. So excavation is going to be necessary for any effective thermal transfer systems.
Mine is pretty small, 10,000 gal., and its still at 82 and quite cold for the wife. Doing the math, if my 7 tons of AC were to run constantly cooling the water of my pool, it would take about 1 hour per degree. (Under ideal conditions.) So if I chilled my pool, it would have NO problem cooling my house even at 120 degrees.
johnlaroux
Member
ano said:Mine is pretty small, 10,000 gal., and its still at 82 and quite cold for the wife. Doing the math, if my 7 tons of AC were to run constantly cooling the water of my pool, it would take about 1 hour per degree. (Under ideal conditions.) So if I chilled my pool, it would have NO problem cooling my house even at 120 degrees.
Are you talking about running chilled water from the pool thru a coil to cool the house? If you are, the pool water would need to be around 42 degrees to work that senerio.
I meant ambient temp is over 100 meaning passive cooling is not effective.ano said:O.K. Your pool rises in temp 20 degrees in a day, and gets over 100 degrees?
Well they certainly can use the data to detect violations of their own TOS. As for what else they can do with it such as report suspicious use I don't know it depends on the TOS and privacy laws. A report of suspicious use is not necessarily a violation of privacy and could then lead to a warrant for the actual data. I'm pretty sure there are court cases for grow houses where initial suspicion has come from the utility company though they were extreme (i.e. causing service interruptions for the rest of the grid). Anyway, we are getting off topic. Back to automation.ano said:Not only would that be an invasion of privacy, but legal evidence collected that way would be thrown out without a search warrant.
apostolakisl
Senior Member
Guys,
There is no way that jumpering power from one house to another is going to be legal. Even if the power co has no tos against that, it would almost certainly violate building/fire codes with two houses flipping back and forth between two electrical services. Whenever changing the electrical around on the main service panel, you are required to get a permit, and there is no way they would pass this.
Now if you wanted to pump chilled water or something from one house to the other, I doubt they could stop that.
There is no way that jumpering power from one house to another is going to be legal. Even if the power co has no tos against that, it would almost certainly violate building/fire codes with two houses flipping back and forth between two electrical services. Whenever changing the electrical around on the main service panel, you are required to get a permit, and there is no way they would pass this.
Now if you wanted to pump chilled water or something from one house to the other, I doubt they could stop that.
