I feel that many of us renewable energy activists do not understand how utility planners think. To us, we see wind as cheap electricity, but to them it is the Predator (of movie fame), something that looks benign and friendly, but at any moment will wreak havoc on their grid by turning off unpredictably.
In order to have a constructive conversation with utility planners, I think it is important to understand their point of view. This is my attempt to do that, with the hope by doing so, we will be able to engage with them more productively.
These are what I see as the underlying principles that shape the utility planning process:
There is no God but Reliability, and Least-Cost is his prophet.
Or, put another way,
The Holy Trinity of electric resource planning: The Baseload, The Cost, and the Holy Reliability.
I use the religious references to make a point: reliability is a religion for utility planners, and people become defensive and angry when you threaten their religion. If we want to work with the utilities, we need to address their real concerns about intermittent renewable resources such as wind and solar. And we have to work with utilities if we are going to modernize the way we get and use electricity.
How do we deal with people committed to this religion? By taking their concerns seriously, and helping them find solutions. In short, when we hear “Wind is so unreliable,” we should say “That’s true. Here are some ways we can take advantage of the benefits of wind without compromising the integrity of the grid. We can be allies in getting regulators to approve rates that allow utilities to get a fair rate of return on these measures that improve reliability, while also allowing more wind onto the grid without impacting reliability.”
Why do we expect them to listen? Because they already have and have to work to deal with a problem that is very similar to unpredictable generation from wind: unpredictable loads. People and companies turn appliances and whole factories on and off unpredictably, and never once do they think about calling up the utility first to let them know that they should have the necessary capacity ready at the appropriate time. Instead, we as consumers just flip a switch, and never expect that the lights won’t come on because there is not enough capacity. If they don’t we get angry.
How do utilities accomplish this seemingly impossible feat of matching supply to capricious demand? They do it with extensive load modelling, so that they can predict approximately how much load will be on the system at any given time with a fair degree of accuracy, and by maintaining “Spinning reserves,” which are basically generators which are already up an running under very low power (hence “spinning”) and turning in synchronization with the current of the grid, like a non-hybrid car sitting at idle.
When there is a sudden increase in the necessary load, they can then increase the power produced from the spinning reserves almost instantaneously, like the motorist of our metaphor starting up when a light turns green.
There are many types of generation that can be used as spinning reserves, not only gas turbines. Hydroelectric dams can work well this way, and can agreements with neighboring utilities to supply power when it is needed, on the theory that two different utilities will not have the same load patterns, and so both utilities can gain by trading power back and forth as needed.
There are many proposals circulating to increase grid reliability and ability to accept more intermittent resources. As is usual in complex problems, there is no one solution, and in this case it will always be a combination of many of these (and some I don’t know about… please leave comments if you have ideas I’ve left out), and the mix will vary widely depending on the unique situation of any particular utility.
- More transmission. Wind not only needs massive new transmission capacity to get the electricity from windy rural areas to the places that need power, but a more robust grid means that widely dispersed wind farms can all provide power to a single utility. Since the weather varies in different places, this has the benefit of making the system as a whole a lot less variable. Denmark sells power to Germany, Norway, and Sweden when their wind farms produce more power than they can use.
- Moving to a national electricity system from the current system of regional grids would also ease the flow of wind power from one region to another.
- Time of Use/ time-based pricing. Time of use pricing allows a utility to charge less or more for power depending on how much power is available at any given time. Time of use pricing is currently a hodge-podge consisting of none at all for some utilities, and others that offer it (or even mandate it) for/to all customer classes. Often time of use pricing simply consists of two prices: on- and off-peak, but the ideal goal for this is to actually have real time pricing, which will even depend on that day’s weather forecast (on windy days, electricity should be cheaper than otherwise.) The ideal goal would be to eventually move all electricity customers to real-time or near real-time electricity pricing, so that customers who are willing to adjust their usage patterns are compensated for the service that they are providing to the system as a whole.
- Demand side management goes hand in hand with time of use pricing. Demand side management involves giving customers incentives to keep their load from peaking too much at any one time.
- Dispatchable/Interruptible loads involve allowing the utility a certain amount of control over their customer’s energy use. The classic example is installing a remote switch on an air conditioner, so that on a hot day, the utility can regulate it so that they don’t all come on a the same time, but rather take turns, lowering the peak demand on the grid. Utilities typically pay their customers for this right for remote control.
- Large scale electricity storage: Pumped hydroelectric, flow batteries, hydrogen and stationary fuel cells, and compressed air energy storage are all ways to store large amounts of power when it is plentiful and cheap (on windy nights, for instance) until it is scarce and expensive (late afternoon and early evening.)
- Distributed energy storage, such as plug in hybrid or electric vehicles with vehicle to grid. Vehicles which charge from the grid can be beneficial even if they are not capale of sending power back to the grid, simply because their owners can charge them only at non-peak times, a practice which is easy to incentivize with time of use pricing.
- New forms of generation that can serve as backup power. Concentrating Solar with thermal storage, landfill gas turbines, and biomass gasification are all possibilities. One often overlooked advantage of IGCC(“Clean Coal”) is that electric power from IGCC is generated by a gas turbine which burns the syngas product of the gasification step. While it is quite possible that carbon capture and sequestration may never be made to work with IGCC, this is one reason (along with lower emissions of traditional pollutants and higher efficiency, which reduces carbon emissions for MWh generated) that renewable energy activists should prefer IGCC to old style pulverized coal plants.
- Increase energy efficiency, especially in appliances that are often used during peak times. In most of the United States, peak load usually occurs on hot afternoons and evenings when air conditioners are running, so replacing an air conditioner with a more efficient one not only reduces overall energy use, it also reduced peak demand. Once again, the institution of time of use pricing would give customers the incentive to upgrade the right appliances for energy efficiency first. Here are two advances in efficient air conditioning I’m particularly excited about the Delphi HMX (formerly known as Coolerado), and thermally driven dessicant cooling.
For another well thought out perspective on energy storage, hop on over the the Ergosphere for the Engineer-Poet’s thoughts.