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According to the U.S. Energy Information Administration, Heat Wave Results in Highest U.S. Electricity Demand Since 2017:
From July 15 through July 22, 2019, a heat wave extending from the Midwest to the Atlantic coast brought extremely high temperatures and humidity to those regions. The high temperatures resulted in elevated demand for electricity to power air conditioners, dehumidifiers, fans, and other cooling equipment. In the hour ending at 6:00 p.m. ET on Friday, July 19, hourly electricity demand in the Lower 48 states peaked at 704 gigawatts (GW), according to data from the U.S. Energy Information Administration's (EIA) U.S. Electric System Operating Data. Electricity demand has not been this high since July 20, 2017, nearly two years ago, when electricity demand in the Lower 48 states hit 718 GW.
NB: The EIA site was giving errors when trying to access the details page for this story. The summary provided here is available on the EIA's main page which is linked to at the top of the story.
[ed: works for me]
(Score: 0) by Anonymous Coward on Saturday August 03 2019, @01:56AM (4 children)
Better than mine. They offer $30 a year to turn off your air conditioner compressor. They do a 15 minutes on, 15 minutes off cycle. They claim most people don't notice, but goodness help you if you have to wait 15 minutes for your AC to come on at all, not to mention the extra wear and tear on your system.
But I have a fully programmed thermostat anyway that sets it to 85 when we are away, so I don't know if that would mean I'd leave the thermostat on 81, and they'd pay me to do to 85, or if they would set it to 89. Big difference there.
(Score: 1, Informative) by Anonymous Coward on Saturday August 03 2019, @05:16AM (2 children)
> They do a 15 minutes on, 15 minutes off cycle.
4 cycles per hour is the standard duty cycle for air conditioners. If you use an electric thermostat, it works like PWM, but with a 15 minute interval. For example, if the cooling demand is only 67% of the AC's cooling capacity, then it is going to run for 10 minutes on, 5 minutes off. The 15 minute off cycle that the power company imposes (assuming that is correct) actually puts less wear and tear on the system, because it remains off for an entire cycle, instead of on for a fraction of that 15 minute cycle like it normally would. The power company is essentially forcing the system to operate at less than 50% capacity.
(Score: 0) by Anonymous Coward on Saturday August 03 2019, @06:44AM (1 child)
That is way too short. I literally just talked to our AC guy (which is how I found out about the program in the first place), who suggested that we should have no more than 3 cycles per hour and no less than 2 on a hot day. Any more or less is a bad sign. In addition, compressor pumps suffer the most problems on the start and stop, not running. They are a lot like lightbulbs, where the sudden surge of energy off the starting capacitor can cause all sorts of problems.
You are also assuming that the cycle of your AC matches with theirs. What if their "off" cycle starts at the same time as my "on", and now the AC is off for an additional 15 additional minutes? Or the AC comes on for two minutes and then it hits? All that just increases the number of "ons" it suffers without decreasing demand. And on top of that, it is only $30 to handicap my AC for the additional headache, potential voiding of my warranty, and wear from the "ons."
(Score: 0) by Anonymous Coward on Tuesday August 06 2019, @11:22PM
Yes, the standard duty cycle is for comfort, not system longevity. People like to raise the thermostat setting if they experience wide temperature swings, which is also not efficient (higher thermostat settings). If the building's heat gain is low, then you can get away with fewer cycles and not experience a wide temperature swing. Old homes might need the 4 cycles per hour.
The compressor does not have enough durability to pressurize an already pressurized system. The compressor depends on its momentum when the system is pressurized. The compressor lockout timer assumes that the low and high pressure sides have had enough time to drain into an almost even pressure before starting again. If you lose power before the lockout timer detects that it needs to lock out the compressor, but the compressor has lost momentum or the AC cycle is not timed correctly for where the piston is at (rotation position wise), then damage might occur. It will draw more current in this scenario, so if you are lucky, the circuit breaker will trip. Ideally, the compressor will have its own breaker, because the circuit breaker is meant to protect the insulation of the wires in the wall, not the appliance. So it also helps to ensure that the compressor lockout functions correctly in a brownout, or very short power outage, scenario.
(Score: 2) by toddestan on Sunday August 04 2019, @02:03AM
I have that system on my AC. In the 10 years I've lived here, I've only ever noticed the system activating once. At first, it was an "Oh Shit!" moment when I noticed that the fan was blowing but the compressor wasn't on, given the entire system is over 25 years which puts it well into borrowed time territory. Then I noticed the lights on their controller box were lit up. Sure enough a few minutes later the lights went off and compressor kicked on. Of course, they could have activated other times and I didn't notice, or I wasn't around.
The system I have doesn't actually save any power for the power company - if the temperature is above the setpoint on the thermostat, the system wants to run. They can kill the power to it remotely, but they can only kill the power for so long, and as soon as they switch it back on the system will kick on. So it really only pushes the demand back a few minutes. Which is probably why they don't use it much. I assume the main reason for the system is for the power company to better handle sudden spikes in demand and to give them time to spool a peaker plant up.
The system that allows them to mess with the thermostat actually would save them power. I can see them doing that a lot more often.