How California kept the lights on

From ClimateCrocks

The recent heatwave showed grid scale battery storage has arrived in California in a big way. In 2020, the state had a mere 250 megawatts of batteries installed on its grid, out of a total statewide peak load of 52 gigawatts (GW). During last week’s heat wave, California had more than 3.2 GW of batteries supporting the grid, more capacity than the Diablo Canyon nuclear power plant. These batteries typically provide four hours of energy, so that’s 150 times more energy from just two years ago. Batteries played a critical role in keeping the grid running, and without them we would have experienced rolling blackouts.

California’s grid has the most installed battery capacity installed of any grid worldwide, and the United States led global investment in grid scale battery storage with nearly half of all investment last year. By investing in energy storage, the state has increased its resilience to extreme weather.

But this is just the start – more and more batteries are coming online in California. Earlier this year, the California Public Utilities Commission issued its preferred system plan, which includes 15 GW of new storage and demand response resources to be installed by 2032. More than 90 GW of batteries are proposed in the California ISO’s interconnection queue, showing strong commercial interest in battery storage. Batteries will be a crucial resource for meeting California’s ambitious clean energy goals, ensuring sufficient firm capacity to keep the grid running even in times without solar or wind energy.

Demand response, where customers reduce their usage either voluntarily or through compensation, plays a critical role in grid reliability and is a key building block in the resource portfolio balancing supply and demand. In extreme cases like the heat wave last week, grid operators don’t always have enough generation online to meet load. In fact, most grids plan to have some small number of outages, as it is very costly to plan to meet load all the time.

Tuesday’s extraordinary text alert asking customers to reduce their electricity demand was successful in avoiding rolling blackouts – it was followed almost immediately by a roughly 2 GW drop in demand. But that sort of mechanism can only work in limited situations, and can’t be called on more than once or twice a year.

Some localized outages were caused by distribution transformers overloading due to heat, and the City of Healdsburg misunderstood the grid operator’s emergency level and started load shedding (rolling blackouts) before they were asked to, but overall the grid held up well.

The weather facing the state, and the rest of the West, was prolonged and extreme. Not only does the hot weather mean record breaking load for the grid, it also means punishing temperatures can force equipment offline. Grid planners need to acknowledge climate change is pushing historic temperatures from extreme to normal and plan for more of these extreme, West-wide, long lasting heat storms.

Solar provided a consistent 13 GW of power to California’s grid last week from 9:00 a.m. to 5:00 p.m. each day, roughly a quarter of total demand. The evening hours from 4:00 p.m. to 9:00 p.m. were the times of greatest grid stress, as solar output drops but demand remains high. This is when batteries helped the grid, charging during midday and discharging in the early evening. On Tuesday, heat wave’s hottest day and the day of greatest grid stress, wind picked up in the evening and provided 2.7 GW of power.

While we made it through last week with the grid intact, California shouldn’t have to suffer such close calls in the future. The state is racing to install more solar, wind, batteries, as well as transmission to connect all these new resources to the grid.

However, supply chain challenges with both solar and batteries have delayed many projects, leaving the state short of meeting its goals. In addition, the pace of transmission development has not kept up with the demand, leaving many projects stuck in the queue waiting to connect to the grid. The state needs a comprehensive plan to deploy new projects and unblock the logjam of transmission development so it can meet its clean energy goals.

Balancing the grid without storage

 Sounds magical, doesn't it?  Yet it's a clever idea which makes sense.

It works like this.  

About 40% of total electricity demand is by households.  Some of that demand is for devices which need to be instantly on when we switch them on, like lights, the kettle or TVs.  However, a big chunk of demand is for devices which don't need to be on at a precise time.  For example, geysers  (water heaters) tend to switch on when the temperature of the water in the geyser drops below a certain point.  But in fact, the geyser could wait for 15 minutes or an hour after that point before it turns on, depending on the state of demand in the grid.  As long as the water is hot when we need it, or the EV is charged in the morning, or the house cooled, or the swimming pool's water filtered, we don't really care precisely when the energy was delivered to make those things happen.  

How it would work in the case of a geyser is that instead of turning on automatically when the temperature drops below the desired level, the geyser would send a request to the grid, asking for a "packet" of energy, say 5 minutes of usage.  The grid would then approve or deny each request based on grid conditions.  Sometimes the need for electricity is more critical.  For example, when the water temperature in the geyser has fallen a lot from the desired level, it would send more requests for packets to the grid more often.  An automated central control system would handle all the requests for  energy "packets" to shape the load in real time.  When wholesale prices are high, the automated operator would delay or reduce the sale of "packets" of electricity, when low, it would facilitate them.

This is a version of "demand management", where big users get a discount on their electricity bills if they agree to being cut off from the grid for, say, 10 hours a year for an hour at a time when demand is high or supply low, except it would be automatic.  Packetised energy management (PEM), as this system is called, is cleverer than manually controlled demand management precisely because it's automatic and real time.  If demand is temporarily too high, demands for some "packets" of electricity would be denied, so that supply and demand would move back into balance.  When there might potentially be surplus electricity, so output needed to be curtailed, all packet requests would be accepted.  Your water would still be hot, your EV charged, your pool water filtered, your house cooled but the electricity that drove your devices would have been drawn from the grid when supply was high and electricity prices low.

It's odd to think we've never had this before.  The grid has been set up to supply all demand instantly, no matter how erratic demand might be, which means it needs far more capacity to cater for excess demand than if it had more control, yet on the other hand often has too much capacity when demand is low, leading to negative prices.

If every household in California and New York had just one device that could consume power flexibly, the power grid would have the equivalent of 15 GW of additional capacity, which is more than 10 times the amount currently available from utility-scale battery storage in these states.

This video from Just Have a Think explains it very well.

Getting to zero carbon in Germany

 From a Twitter thread by Philipp Litz:

Germany plans on going climate neutral by 2050 the latest. Most of the electricity produced will come from wind and solar. But what is the strategy on keeping the lights on, when there is no wind and sun, and coal, natural gas, or oil plants will be phased out?

First: There will still be plenty of dispatchable capacity. However, these will not be nuclear, coal or classic natural gas power plants, but primarily small, decentralized gas units that are operated with (green) hydrogen.

Second: Pump and battery storage (both stationary and mobile in cars) are becoming increasingly important. They store excess electricity in times of high wind and PV generation and make it available when it is needed. In addition, traditional demand is becoming more flexible.

Third: The European electricity market will grow even closer together than today. This means you can take advantage of balancing effects of renewable energy generation. Also, sharing backup capacities makes it cheaper for everybody.

Interesting demand response

"Demand response" is, properly, paying big users to stop using electricity at times when demand exceeds capacity.  It is not the same thing as "load shedding" (alias "blackouts") which is from the point of view of consumers involuntary and affects everyone within the area served by a single (or several) electricity substation(s).  What's being talked about in this article from CleanTechnica is not strictly demand response, but is something akin to it.  And very clever it is too.

Hawaiian Electric (HECO) recently added 2.5MW of grid services to its grid, allowing it to store energy during peak solar and wind production periods, and did so without any traditional batteries, flywheels, or pumped hydro. Even better, the hardware required is very minimal, and in fact, most of it already exists in every residential grid in the world.

Demand response grid services are important because the times when renewable energy is flowing do not always match up with when people are using electricity. In the below graph, you can see that if we can shift the energy use from the peak demand time (red) to times when peak renewable generation is happening (yellow), you can use more clean energy. Pretty simple, right? As always, the devil’s in the details.

Hawaii’s startup ecosystem is not well known, but the confluence of high costs (of everything), being 3000 miles from the nearest landmass, and a steady influx of capital from military and tourism create an interesting space for innovation. Given that Hawaii, like many islands, is largely powered by diesel generators, the cost of electricity is insanely high, making Hawaii a great laboratory for cleantech startups.

One of these startups, Shifted Energy, a developer of software and controllers that retrofit electric water heaters, has partnered with Open Access Technology International (OATI) to outfit up to 2,400 water heaters with smart controls through Hawaiian Electric’s Grid Services Purchase Agreement. Shifted Energy installs controllers on residential water heaters to allow utilities to effectively use them as batteries. The company will deploy a 2.5 megawatt storage system for HECO, the company announced last week, creating what’s often referred to as a virtual power plant, or VPP.

“The controllers are free to participants and property managers,” says founder and CTO Olin Lagon, “and participants in this Hawaii program will receive a monthly bill credit between $3 and $5, depending on how often their heater has the ability to contribute to the program. But, more importantly to us, a lot of people are renters, multi-family apartment dwellers, or can’t afford solar panels, batteries, or other clean energy technologies. Our technology empowers everyone with an electric water heater to participate in the fight against climate change and the transition to cleaner energy.”

The company has spent years optimizing an algorithm that takes into account typical hot water usage, so as to maximize the positive outcome and still supply hot water when needed. Here in Hawaii, peak demand time (about 5–9 PM on weekdays) is a time when the grid is strained, and when the most dirty energy is being used. So, by shifting the time a water heater kicks on and warms up to times when there is excess solar on the grid, the technology can help reduce the peak demand, and therefore, the amount of dirty, expensive energy that is used during that time.