California Utilities to Store Off-Peak Power In Blocks of Ice

I saw this on TV a few years ago, seems like a real good idea. Only problem is where I live utility cost is only based on total monthly usage. So this type of air conditioner would only reduce my cost slightly, by cooling the ice at night when it is cold out side. Why should I spend quite a bit more money to get something that only saves me a marginal amount of money. If I were charged different rates depending on when I used the power it would probably be worth it. It would also be nice if the utilities would subsidize them a government mandate would work also. If we just rely on 'green people' to use it we will be waiting a long time for anything to change.

Although it is nice for the utilities to be able shift peak demand to off-peak demand, the net energy use will likely be higher than before using this unit, due to inefficiencies in storing ice.

In my mind the best thing to do is still to let the earth be our heat storage. Geothermal heating and cooling really is the way to go, imho. It actually consumes far less energy on a net basis to use geothermal heating and cooling, while still reducing peak power demand. The ground (below about 5 feet or so) stays at around 50-55 all year round (depending on location, and with a few exceptions) due to the thermal inertia of so much mass. That is great for both heating and cooling by using the earth as a heat battery.

I don't think that having to generate MORE net energy just to help offset peak requirements is the best long-term solution.

buckrodgers
If you could offset the energy differential by solar collection and storage for night use this may make it a more viable solution. Not the best just a little better.

Improving the insulation would make this more efficient. A couple of days back there was an article on using aero-gels for super efficientn insulation.

A few years ago I saw this concept in a "green building" design. The idea was to freeze giant blocks of ice in the basement at night, and blow ventilation air over the blocks during the day to cool the building.

It seems much less efficient to put the ice storage tanks on the roof in the hot California sun, but perhaps it is cheaper to use the existing rooftop AC units than to install a new coolant system in the basement.

for those concerned about increasing total energy usage in order to decrease PEAK energy usage, you should know this:

Many of our electrical power plants run 24-hours/day despite the lack of demand for electricity in the dead of night. They run so much more efficiently (at least from a cost and often from an energy/fuel perspective) when run at a constant, minimum level that power companies simply do not turn them off.

This is a large part of what is called "baseload" power (although the actual definition of baseload is different and includes some other generation as well). These always on sources constitute a large fraction of our energy generation. There is another fraction of our energy generation that comes from power sources that are easy to turn on & off. These sources are turned on during peak hours, run only as much as needed, and do not produce pollutants when not running. If we never turn them on, they will not produce co2 and pollutants like certain oxides.

The always-on generators, however, run and produce these chemicals even at night. A vast amount of electricity is generated and instantaneously wasted during these hours. This is because there is more "always on" generation then there is "always on" demand for electricity.

What this device does is say, okay...we've got "free" power, co2 wise, because the plant will be generating and releasing co2 (and all the other inevitable by-products) whether the energy is used or not. So...the question then becomes, can we use the energy that would be wasted in order to prevent a sometimes-on (or "peak only") generator from turning on and generating emissions during the day.

If we leave peak-only generators off more often, we save energy, fuel, and emissions. If we run the ice machines, we use up energy and fuel and create emissions only to the extent that we would have created them anyway - the use of these machines adds nothing to the national energy, fuel, or pollution budgets.

It is unfortunate that the writer did not explain that this ice creation uses "free" energy...likely many people came away with the impression that only money and not fuel/energy/emissions were being saved.

--)->

bicrip, it would be nice if what you said was true, but, unfortunately, it is not.

It is true that many baseload power plants run 24/7, but that energy is not instantaneously wasted. If that was the case, where do you propose it goes?

The truth is, the utilities generate exactly enough electricity to meet demand at all times. That is how the grid stays at 60Hz. If utilities were producing excess power, the frequency of the grid would increase. To answer the question that I asked, THAT is where excess power instantaneously goes.

You are correct, however, in saying that these ice storage solutions would save emissions. The baseload units are operated in the order of lowest fuel cost to produce electricity. Typically, nuclear first, then coal. These two produce roughly 60% of the electricity in the US and meet demand at night. The peaking units are turned on in order of hydro (gasp!, renewable energy), petroleum, and natural gas to meet demand during the day.

Gas turbines are the highest cost, highest emissions power source and would be offset by the use of these ice storage solutions. That is where the emissions savings would come into play. As previously stated, the only way consumers would save in this arrangement is if they got on a plan where off-peak energy is at a cheaper rate than peak, similar to what is proposed for charging electric cars.

Thrown into the mix are solar, wind, etc that make up 3% of the total energy into the grid. These also offset the peaking units when they can, but as we all know, solar only works during the day and wind is intermittent in most cases. They are, however, welcome additions to the grid and the peaking units compensate for their input easily. As soon as the grid frequency increases from one of these sources, the peaking units see the increase and throttle back to maintain frequency within 0.1 Hz.

I think it's stupid that people think they NEED A/C, to the detriment of the environment life depends on. Thousands of years of history without A/C, and now we need it?

Lame. Take a freakin siesta instead.

mattyb is entirely correct, as this reduces peak use (usually the most exspensive and dirty) and converts it to base use (usually the cheapest and next-to-dirtiest, sans nuclear). By moving the power use to night, you allow more energy to be created with the more efficient base sources and less demand on the on-of sources.

That, by the way, is why solar/wind are not the panecea everyone wants - they add instability to the grid. If used in masse, they would force the companies to reduce base generation (to avoid power spikes on super sunny and windy days) and them compensate when the wind stops and the sun goes behind a cloud for a few minutes.

Yes, this system bleeds energy, but even a system that looses 50% of its input is better than an energy source 4 times as costly.

Also, these are not really designed for basic residence. These units are developed for large buildings and stores with many cubic feet of air to cool than several houses. After all, ice benefits from scale - a 20' ice block takes 8 times the energy to freeze compared to a 10' block, due to 8 times the volumn (the copper pipes of coolant give an equal surface area / square foot exsposure to cold) but takes a great deal longer to melt from non-coolant heat due to decreased surface area per square foot of ice.

And while geothermal is great, it is exspensive to put in to new construction and almost impossible to retrofit into large urban structures.

Agree entirely ... anything that can reduce the Peak DEMAND is a real bonus ... even if the efficiency isn't that crash-hot at the moment. This idea has been around quite a while .... it's simple proven technology that should incur low investment risk.

Big question however .... is something as simple as this (or a variant of it) of any practical use in helping solar/wind/etc gain a foothold as "a more cost-effective package" providing a stable SUPPLY part of the equation.

I had envisioned something like the ice bear a few years ago but there is not - as yet - a big demand for air conditioners in Scotland. That said there are some interesting points. Refrigerating at night when the air temperature should be lower should require less energy as the thermal gradient is less ( the difference in temperature between ice and the ambient air) about 2 cubic meters of ice is equivalent in cooling power to the daily output of many household air conditioners.
An interesting opportunity arises in areas that require desalination. When ice forms on the sea, or brackish water, the ice does not take up the salt. So a cascade of blocks freezing and thawing could desalinate a lot of water, with little extra energy cost. On the subject of air conditioning there are possibilities for compressed air mains in high rise urban areas. Space inside tall buildings is seldom cheap and a compressed air pipe can transport as much air as a ventilation duct,but take up much less room. Expanding that air at the desired location can produce power and absorb heat. Processing and compressing air is probably done much more efficiently on an industrial scale, especially if it is done next to an outlet for the heat produced. In an earthquake prone area, a compressed air main is less of a hazard than some power delivery systems

Unfortunately MattyB is not correct. A lot of power is wasted at night. It is essentially discharged into the ground. You can not really cycle coal or Nuke plants, so if less power is needed than is produced, bye bye extra power. No one gets to use it.

He is also incorrect in saying that gas turbines (peak) have the higher emissions, as they are actually much lower than coal (baseload).

Also incorrect is the statement that hydro is a peaking option. Water is a free fuel. These always run.

Sorry, you really don't know what you're talking about. ;-)

Everybody's a smarty pants.

SLNuke87 wrote:
"Also incorrect is the statement that hydro is a peaking option. Water is a free fuel. These always run."

That all depends on where you are and what time of year it is. During summer months, our dam ONLY opens for the highest peak demands because our summers are hot, rain is scarce, and our water is very far from free.

So who knows what you're talking about?

haha touche!!! That's a good point!

It is absolutely untrue that any power in the middle of the night is lost to the ground. If you goto oasis.caiso.com you can look at wholesale prices of electricity inside of California's Independent System Operator. If balancing load and supply were as simple as discharging power to the ground you would never see negative prices but if you look you'll see that negative prices can exist. "fuel/energy/emissions" cost money so if you're saving money then you have to be saving at least one of those. Whoever said that we should stop using A/Cs apparently didn't hear that people die of heat stroke not to mention the fact that that is insane "Hey lets invent something that will make us more comfortable and then not use it". Coal plants do not need to be cycled all the way offline in order to produce less power. They have an operating range that they can stay between. Nukes do too but their marginal costs are so low and it is a difficult task for them so they won't do this unless it is going to be an extended period of time. Coal is the dirtiest. Natural gas is far behind coal in emissions but there are a wide variety of natural gas burning plants. There are older plants that work by heating water in a steam turbine, these produce the most emissions and least electrical energy per unit of fuel burned other wise known as the heat rate (megawatts per million BTUs). There are combustion turbines which work similar to jet engines in that the gas is burned to spin a shaft directly. Then there are combined cycles which have both combustion turbines and steam turbines which harness the exhaust heat of the combustion turbine to generate more electricity than the CT alone. Generally the older versions are required to stay on all the time because it can take up to a whole day to get them turned on. These plants are the ones you most want to get offline. The peaking plants that will run for 4-8 hours in the daytime are generally less than a decade old and can be started in 10 minutes or so and since they're newer generally pollute much less than their older cousins. FERC mandate that an electrical utility's most important job is to keep the lights on. If they keep the lights on then the cost of doing so is a distant second. Therefore a utility has an incentive to keep their old clunkers online rather than finding more cost effective ways of supplying the load. Oh and marginal heat rate curves of steam turbines is rising which means that for the "old clunkers" and coal plants they are most efficient near their minimum operating level but for combined cycles and combustion turbine type plants they are most efficient at the upper end of their operating range. New investment for power plants only occurs when there is a capacity shortage, not because of greater efficiencies in newer plants relative to older ones. As such devices like this will tend to keep net peak demand lower which will delay required investment in new plants.

Can anyone tell me where I can find info related to "megawatts per million BTUs" posted by skatastic, on 4/26/10.

Really I would like to see a graph for different power plants, specially oil burning, showing the relationship between load [power being drawn from the generator] and oil consumption, let's say from no load to full load graph.

One of the reason is that many articles make reference to x amount of pollution will not be created [thrown out to the atmosphere] when a solar or wind installation goes "online".

They give the false impression there is a direct relationship between electric power consumption and fuel/oil burning at the power plant.. We only need to take the issue to the extreme to prove it false.

Let's say the power plant is on but not "online" [or the whole city turned the power off on purpose or by accident]... do that means the power plant will no consume any fuel?

The same as when your car is not running but engine is on/iddling.