What is the Smart Grid?

By Alan

If you aren't really sure what it means to have a Smart Grid, then you aren't alone. A few weeks ago, I had the privilege of meeting with several hundred of the nation's electricity industry and government leaders at Gridweek 2009, and each attendee had their own take on what the phrase "Smart Grid" meant. I'm of the opinion that it should end up like an organic system. However, most seem to agree on a few common ingredients about the Smart Grid.

Smart Meters - The AMI (Advanced Metering Initiative) is aimed at replacing the millions of old manual/mechanical power and gas meters with digital meters that can not only report total consumption over a month (just like your power billing cycle), but could also report, minute-by-minute, the current usage of the household or company back to the utility, plus a bunch of other measurements like voltage, power frequency (remember how important that is), even outside temperature. Depending on the manufacturer and the controlling utility, the meter might also be able to receive information from the utility about current and near-future prices, and even curtailment signals for "Demand Response."

Demand Response - The ability for a utility to reduce the amount of power being consumed immediately or at a particular scheduled time. Since large amounts of electricity can't really be stored for any length of time, utilities have to generate power for the amount of power being used at the time. There isn't much choice. If everyone turns on their air conditioners at the same time, the power grid probably can't support it for long.

Demand Response for residential customers usually targets the biggest "cycle-able" electrical usage in the household: Air conditioning and water heating. If they cycle off the water heater for 15-30 minutes, the temperature might drop a few degrees, but it doesn't cause any serious impact to the house.

When the grid is under stress, the utility sends out signals to remotely turn off these items for a short period of time, turning off first one neighborhood, then another. By cycling on and off large groups of houses, the grid usage drops considerably.

The same concepts can be used for commercial stores and buildings, factories and other industrial customers. The utility sends a signal to the building or factory and it shuts down non-essential power usage for a short period of time. The ideas become more interesting when the grid authority allows customers to bid on how much they are going to drop power usage. Prices can then be raised or lowered in order to provide more incentives to reduce.

Decentralized Generation - The concept of running power from one gigantic power plant near the edge of the city makes sense for a number of reasons. Usually the power plants are a source of pollution; air pollution, noise pollution, water pollution, and maybe even gamma ray pollution. Nobody wants a city-wide power plant in their backyard. (Okay, there are exceptions to the rule, like hydro-electric dams that make nice pools and falls in the city parklands, but they are still noisy and could flood the city if not managed properly.)

But what if the power plant were the size of a tractor trailer? Or what if it was a medium sized wind turbine located in your neighborhood, with dozens of them located around the region, making the power delivery more efficient, because it's closer to the places the power is being used.

This is a cool concept, but it gets to be difficult when you realize that you have to synchronize all of these little mini plants to the same frequency, and have them ramp up and ramp down for power usage as needed.

Sustainable Power Generation - This ingredient is less widely accepted as part of the Smart Grid, but having sustainable power as a major component of generation means that the Smart Grid is necessary. Everyone agrees that the future of the grid requires more generation, and by using sustainable resources, which are, by nature unpredictable (pun intended). Demand Response becomes essential, rather than just optional.

Consider that most power generation is predictable. Nuclear power plants run at full power whenever they are turned on, because they run best (and cheapest) at 100%. Coal power plants (which make up about half of all power generation in the United States) are difficult to start up and shut down, so once they are fired up, they need to just burn in order to stay efficient. Natural Gas power plants can start up and shut down quickly when they are, but are typically very expensive to run.

Most sustainable power sources (Wind, Solar, Ocean current) are not able to continue non-stop. The wind stops, the sky gets cloudy, and the ocean has storm tides. These unpredicted interruptions could have devastating effects on an electrical grid that is relying on that capacity.

Since (say it with me), you don't store large amounts of electricity for any length of time, then if you suddenly lose major portions of generation, then you need to either:

1. Quickly add more power
2. Just as quickly reduce the need for more power

Both of these choices require some detailed and timely knowledge about what is happening on the grid. If the wind suddenly dies, then the power requirements of the grid need to be analyzed, the differences calculated, and signals sent out to start up power generation, and to reduce the power being used, within minutes or seconds. The very stability of the grid is as stake.

Communication - The final piece to making the Smart Grid a comprehensive solution is the concept of communication and coordination from the consumer to the utility to the generation plant to the grid authority to the marketplace. The kinds of data needed include prices, power usage, temperatures, voltages, etc. Those values have always been measured, but not always communicated in a timely fashion.

The ability for a customer to know how much power they are using every minute is a new reality. The ability for the utility to know what every single consumer is going to need for power later in the day is a possibility. The ability for the grid authority to know when parts of the grid are in trouble is essential in the new world of intermittent power sources.

The Smart Grid: What is it? There are dozens or hundreds of other parts to make up the new intelligent grid. Just like a body's systems, it should be well informed, can react quickly, and can operate locally in cooperation with the entire system.

To read more about the US Government's take on the Smart Grid, you can read their introduction here.

Comments

[Jeff]

Excellent article, Alan. Thanks for the info.