Demand Response, Duck Curves and other jargon
The use of EVs to stabilize the grid should be happening now
BY JOHN HIGHAM: LEGISLATIVE DIRECTOR OF THE ELECTRIC AUTO ASSOCIATION, ELECTRIC AUTO ASSOCIATION BOARD MEMBER
The Duck Curve is the result of actual power demand with renewable sources superimposed. Courtesy of CAISO.
Late last month, California’s Governor Gavin Newsom signed an executive order setting the goal of banning the sale of gasoline-powered vehicles in the state by 2035, a long-time goal of many activists and environmental organizations. Although there is still much work to be done before this goal can be achieved, the enactment of the mandate is a a very important milestone.
After Newsom’s announcement, social media lit up with all kinds of objections: All those electric vehicles (EVs) plugging in at once on an antiquated grid? Pandemonium will ensue, dogs and cats will be living together, and civilization will plunge into darkness. Except that’s not even remotely true.
EVs are a great way to stabilize the grid; it isn’t even difficult. It can be (and has been) done on grid scale. In fact, 5 years ago I was one of 100 participants in a study that showed exactly that.
It’s about the timing
The load of an EV on the electrical grid is roughly 25% of the load of a typical home. What’s different is how those loads are represented on the grid and the time when the loads are active It’s all about Demand Response and Load Balancing. As Edmunds put it:
What if a gallon of gasoline cost $3 at breakfast time, was free at lunch, bumped up to $8 in the afternoon, but was only $2 in the middle of the night? Welcome to the world of charging up plug-in electric vehicles.
Once you understand that consumers can (and do) change their behaviors based on simple economics, you can understand how EVs will not only help stabilize the grid, but make it more efficient, too.
A fundamental law of physics
Energy can be neither created nor destroyed; it can only be converted from one form to another. I wouldn’t be surprised if every engineer at California Independent System Operator (CAISO) has to get this tattooed on the inside of their eyelids as a condition of employment. That’s because it’s their job to ensure just the right number of electrons are pumped onto the grid as they are consumed. In real-time. If they screw it up, the grid goes unstable.
An airline executive once said you don’t build an airline based on demand over the Thanksgiving holiday. Essentially, the idea of Demand Response is to flatten the curve shown in the chart above by giving grid operators the ability to turn off loads. Going back to the airline analogy, think of Demand Response as overbooking; instead of asking for volunteers to be compensated for giving up their seats, the electric utility is asking for volunteers to be compensated for giving up charging their car (or running the AC and so forth).
There have been studies about EVs supplying energy to the grid (known as Vehicle to Grid or V2G). That’s not what we are talking about here. While V2G could be an important technology at some point in the future, it has a set of logistical headaches that frankly may never be worked out. Studies have shown, however, that giving control to grid operators over EV charging is 80% as effective as V2G, but with far lower costs and fewer logistical headaches. This was acknowledged by Michael Liebreich in his address to the Bloomberg New Energy Finance Summit.
Demand Response programs are nothing new. Hydro-Quebec has been using them for decades by giving financial incentives for allowing the utility to control residential heating and air conditioning during periods when the grid is struggling to meet demand. Many other utilities participate in various other residential Demand Response programs.
Load Balancing in One Chart
Additionally, there are load shifting technologies that store excess energy for later release. This phenomenon has been explained by the infamous “duck curve” (see chart above), displaying a day’s energy demand with generation from renewable sources superimposed. This net is the energy generation required by traditional energy sources (large hydro and what is known as thermal being 2 of the most common). Anticipating ever-increasing renewables coming online and extrapolating out a few years, the family of curves is said to look like the profile of a duck.
Just as the sun is setting and significant solar production is winding down for the day, people are rushing home, plugging in their cars, cooking dinner, and turning on the air conditioning. In simple terms, renewable production is dropping just as demand is starting to peak in the late afternoon and early evening, and a lot of power needs to come online, sometimes too fast to bring on new energy production. The chart above highlights a case from February 2016 of an almost 11 GW increase over just 3 hours.
Companies are already competing for grid scale energy storage for excess power generated earlier in the day. The storage can take the form of huge battery farms such as Tesla has deployed in Australia, to simpler forms of storage such as pumping water uphill or building a concrete tower.
This is where grid-scale energy storage can flatten the duck by soaking up excess energy from renewables as fast as it is generated and then releasing that energy as the sun sets and the wind dies down.
Grid scale energy storage. Economic incentives to shape consumer behavior. These are the keys to supporting EVs of the future on the grid. We already have the capacity to generate the required energy, and all of the technology necessary exists today.