AB 813 & Renewable Energy Curtailment

Putting the concerns to rest, and NRDC’s claims in context

By Tyson Siegele

Over the last four years, proponents of a regional grid operator have used misleading messaging about renewable energy curtailment. They say that large amounts of renewable energy in California are being wasted.

After framing renewable energy curtailment as a huge issue in need of a fix, they offer up Assembly Bill 813 as the solution . They say California should give up control over its grid operator to energy industry insiders from across the west, many of whom would hail from fossil fuel dominated states. That’s right; proponents of AB 813 are proposing that the way we “fix” a tiny percentage of curtailed renewable energy is to turn our grid over to fossil fuel interests.

Advocates for the adoption of a regional grid have only had success with this argument by highlighting raw numbers about curtailment without the context. A recent NRDC article published just days ago is a prime example. In the following few paragraphs, I’ll put curtailment in context and in turn you’ll be able to put the idea of a regional grid operator in context.

Renewable Energy Curtailment – Why Does it Exist?

NRDC article:

“Curtailment during the month of May surged from 10,000 megawatt-hours (MWh) in 2014 to over 70,000 MWh in 2018. This is enough clean energy to power more than 130,000 homes in California for a month.”

While the article says that curtailment exists, it doesn’t mention the cause.

California has never achieved a single second of 100% clean energy on the grid and the following graph hints at the reason why. The graph below, published by KQED, shows a spring day in 2016 with one of the highest levels of renewable energy curtailment that year.

The notes I added in red, highlight the real problem in California which is that fossil fuels are allowed to run while CAISO shuts down power plants that could be providing clean sources of electricity.

Renewable Energy Curtailment – How much is there?

The NRDC article highlights a report by a group called Secure Our Energy Future which says:

“In the first seven months of 2018 alone, California curtailed over 315,000 MWh of renewable generation: enough clean energy to power San Francisco for 20 days.”

They say in their article that these items are, “key findings of a new report.” Before digging into the quote, let’s take a quick look at that report.

  • The “report” is two pages in length
  • NRDC staffers wrote the report

This comes dangerously close to sockpuppetting, a tactic used to manipulate public opinion. If NRDC wants to publish information, they should do it. They should not pretend that they are reporting the findings of others.

Now let’s put their curtailment number in context. 315,000 MWh sounds like a lot in the context of a city with fewer than a million people. What happens when we look at the amount of annual renewable energy curtailment as a percentage of the California energy system?

In 2017, California renewable energy curtailment amounted to less than 1 / 600th of the overall system electricity. (380 GWh vs. 292,000 GWh).

The difficult to see blue sliver is the main reason given for why California should give up control over its grid operator.

Renewable Energy Curtailment – Is it getting worse?

NRDC article:

“Important new evidence just surfaced about a growing problem that burdens California’s clean energy transition: we are quite literally throwing away increasing amounts of clean energy.”

In the article, NRDC says that curtailment: “is growing”, “has surged”, “is increasing”, “has risen significantly”, and references a “new peak.” They are quite clear that curtailment has gotten worse. That’s right, it has “surged”… to far less than 1% of the California electricity supply.

Let’s take a look at the most recent information available, the first 7 months of 2018, and see if there really is more curtailment this year than there was last year.

Before we draw too strong a conclusion from the year over year decrease, let’s take note: one year is not necessarily the beginning of a trend, and rather than a decrease, what this really shows is that the curtailment in 2017 and 2018 is essentially identical.

And that brings me to the next quote.

NRDC article:

“Unless something changes, if California meets its target of generating 50 percent of electricity from renewable resources in 2030, the Union of Concerned Scientists estimates that 5 percent of available renewable generation would be curtailed.”

The caveat, “unless something changes” is important.

The UCS study was published in 2015 based on research from 2014 and before. The renewable energy landscape alters dramatically from year to year. Here are a couple of differences from 2014 to 2017:

Things have definitely changed. So let’s look at what the UCS study says will happen if we account for the world as it is today.

Below is the UCS graph (pdf page 7) that shows a hypothetical 5 percent curtailment (or 4.8%) if one assumes 0 GW of flexibility. However, as system flexibility increases, curtailment decreases.

Thus we need to know how much flexibility the system has. One source of flexibility is energy storage. The California Energy Commission reports on energy storage. California has:

  • 4.5 GW of pumped hydro
  • 1.3 GW of mandated future storage procurements

By accounting for just the existing pumped hydro and mandated storage, we will remain below 1% curtailment when we hit the 50 percent renewable energy target. But several more tools will provide additional flexibility:

It would appear that the UCS study finds that California will not have any significant renewable energy curtailment on the path from our current 29 percent renewable energy to 50 percent. Knowing that California is quickly ramping up its energy flexibility strategies, and based on the UCS study’s findings, perhaps the slight drop in curtailment from 2017 to 2018 is the start of a trend. The good news is that with less than 0.2% renewable energy curtailment, California has plenty of time allow the story to develop.

NRDC: Living in the Past

In 2010 many people thought that the only way to achieve high percentages of renewable energy on the grid was through a national grid system. No one thought we would see the rapid decreases in the costs of renewable energy and battery storage. NRDC appears to be stuck in that past mindset. They have built up curtailment into a boogeyman which can only be defeated by a regional grid operator.

If California gives away its grid control to others, no one knows what rules they will set or how many additional transmission lines Californians will pay for. Those uncertainties make an RTO unacceptable, especially in a world where analysts predict that solar prices will soon fall to 1.4 cents/kWh, 60% less than SDG&E customers are already paying for transmission.

It is surprising that NRDC prefers risking California’s clean energy future on the wildly optimistic assumption of a benevolent Trump administration instead of embracing technological solutions for increasing renewable energy which are staring them in the face.