By far the most popular “Yes, but…” about wind and solar electricity is, “Yes, but what do you do when the wind don’t blow and the sun don’t shine? We need power when we need it, and we need it, well, all the time.” This used to end the discussion.
But not any more. Advances in technology, including electricity storage and “demand response” technology, are on target to realistically address the intermittency issue at scale. In the storage arena, battery arrays, hydroelectric plants and pumped hydro will provide part of the answer, storing energy when more is being produced and putting it back onto the grid as needed. But another approach is demand response. Simply put, demand response is a way of controlling demand to respond to supply.
Electricity needs to be used or somehow stored at the instant it is generated. Conversely, when electricity is called for, it needs to be supplied immediately by a source. When you turn a light on in your house, some generator, somewhere, has to increase its output to accommodate it.
The traditional energy market approach to electricity is that the supply is always determined by the demand. For example, in the evening when people come home from work and school and turn on their TVs, lights, appliances, etc., the demand for electricity peaks. Power plants are actually turned up to accommodate that increase, and so called “peaker plants,” usually powered by natural gas and less efficient than other generators, are turned on.
Demand response functions by controlling the demand to align with the supply instead of the normal supply-aligning-with-demand.
Some forms of demand response have been around for many years. Electric utilities make deals with large industrial customers to cut back on their power use when the rest of the grid is experiencing higher loads. The customer benefits because they are actually paid by the utility, while the utility benefits because paying the customer is cheaper than generating extra power or building new generation facilities.
Another already in place way of easing peak loads is “time-of-use” pricing, in which customers are incentivized to use electricity at off-peak load times. The cost per kwh decreases at low demand times, and a customer might install a timer on a water heater so it mostly goes on at the times when rates are low.
Finally, there is the rather unpopular load shedding. This typically happens during extreme hot or cold periods, when the utility simply cuts off power to parts of their service area. This generally results in some unhappy customers as there is no reward for the involuntary loss of power.
In these examples of current power grid demand response, the time scale over which the power level is controlled is measured in hours in response to predictable consumer demand. Renewable power sources such as wind and solar, however, provide a rapidly fluctuating source of power, and thus a timing challenge for optimal use.
So today, we have more, better technology to address this problem. These include “smart” grids, “smart” meters, “smart” appliances and electric cars with “smart” chargers. The highest energy users in a home are typically the climate control (heating or cooling), water heating and – more and more – electric car charging.
A couple of examples: You get home from work at 5 p.m. and plug in your car, go into the house to take a shower and maybe start cooking. When you and thousands of others do this at the same time it puts a strain on the system and the generators have to ramp up. But your car wasn’t fully discharged and you don’t need it until morning. So your smart meter tells your car “Hey electricity is expensive right now. You might want to wait to charge.” Your car answers, “Wow, I actually have 10 kWh stored in my battery, can I sell it back onto the grid, or use it to heat my water?” The meter says “Sure, I can arrange that.”
It’s the middle of a partly cloudy but quite warm day. Your air conditioner is running to keep you comfortable, but so are thousands of other air conditioners. It’s okay at the moment because there is plenty of sun hitting the solar farms that are powering the AC. A bank of clouds passes over the region reducing the solar output. Normally some natural gas plants need to be turned on to feed the air conditioners. But instead the grid tells your AC that for the next 45 minutes the energy is going to be more expensive because it’s coming from expensive gas. Your AC says, “Oh I’ll just turn down for a bit until the price goes back down.” You barely notice the difference, while saving money and reducing pollution.
As we move to a future of renewable-based electricity supply, more and more of these congenial conversations among cooperative appliances and energy suppliers will be taking place. Just imagine how this will raise the average civility level in society! Even if they started arguing, it would be better than things like wars in which the biggest fossil fuel suppliers can get whatever they want. Further, we might learn from their example that we can actually get along fine by figuring out what we really need, and being satisfied with that.
Paul Stancioff, PhD., is professor emeritus of physics at UMF. Cynthia Stancioff re-words everything he writes. Email: pauls@maine.edu or cynthia.hoeh@gmail.com Previous columns can be found at https://paulandcynthiaenergymatters.blogspot.com/.
Comments are not available on this story.
Send questions/comments to the editors.
