Iowa Grid Power demo

Laptop CPU clock speed and power consumption

Modern laptop cpus generally have the ability to vary the clock speed of the processor under operating system control. Normally, when the cpu is in use, the OS ramps up the clock speed to get work done faster. I've written a simple application in Python to graph the power consumption of a laptop. The screenshot below shows three different regions.

The first region, when the laptop is using about 25 watts, is running a computational chemistry simulation called GAMESS that simulates atoms and small molecules using theoretical quantum chemistry. This first run is a simuluation with the laptop in power saving mode, so the CPU clock rate is limited to 1Ghz. It took about 200 seconds for this simulation to run. However, when the clock rate is increased to 2Ghz, and the simulation is restarted, it takes about half the amount of time, but almost double the power. Normally, scientists are impatient people, and want their results as soon as possible. So they will always want to use more power. Finally, the upward trend on the right side of the graph is the power consumption of the powerDemo graph program, which has not at all been optimized. yet. I wrote it as a demonstration and proof of concept, to give a nice visual indication of how much what you do with the cpu changes power consumption. What surpised me though, was that it took me longer to write the Iowa Grid Iowa Power fund proposal, than it did to write the demo app (which was about 2 days). If you have a linux laptop, you can try it out by downloading the Python code


Now let's say for example, that the load on the city of ames utility is approaching 105 MW. The city has probably instituted the Prime Time power program, which cycles air conditioners off for 7 minutes of every hour. If we can convince the scientists at Ames Laboratory to wait a little longer for their results (not an easy task, btw), we might be able to reduce the load on the city utility by 100KW.. so from 105.0 to 104.9 MW. This by itself isn't a whole lot. But the same software that talks to a city of Ames web site and figures out what the load (or power cost) is could be running on 10,000 laptops. Ames has 50,000 people, and the university has 25,000 students, so that number might be a little high. If half of those laptops pop up a message saying "Peak power alert, can I shut down ?", and then go into hibernate mode, or turn off, we've just shaved another 25KW from the peak load. If we can do the same thing with 5000 desktop computers, which can draw 100-500 watts, that is a LOT more power.

This is just making computer loads responsive to the grid. Now imagine if your computer set your thermostat up 5 degrees. Or delayed starting a clothes dryer. If the computer just tells you what's going on with the grid, maybe you'd change your behavior. Now that little bit of computer code just eliminated the need for a new coal power plant, and increased demand for wind generation. No arguments, politics about rates, or lobbying for a carbon tax. Just millions of computers and people, All making a little change for the better.

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Contact info: email hozer at hozed dot org