Can California really be carbon-free by 2045?

Solar panels on the roof of the Los Angeles Convention Center. Image: Getty.

California governor Jerry Brown recently signed a new law mandating that the electricity the state consumes not cause carbon emissions by 2045.

He also issued an executive order that goes even further: it commits California to “achieve carbon neutrality” across the board and not just for power generation by 2045. Together, these steps codify California’s ongoing transition away from relying on fossil fuels for energy. This effort has been ramping up since 2011, when Brown signed another law committing the state to deriving a third of its energy from renewable sources like wind and solar power by 2020 – not including big hydroelectric dams.

Based on more than 30 years of research related to solar energy, by my assessment, California can meet the law’s ambitious goal as long as it continues to implement programs that encourage the rapid expansion of renewable energy in the state.

A growth industry

The new law actually sets multiple targets rather than just one. It commits California to draw half its electricity from renewable sources by 2026, a share that would rise to 60 per cent by 2030.

To take the next step, rather than mandating that all power be renewably sourced, state lawmakers established a 100 per cent “zero-carbon” goal. They did not define this term, but it is understood as including wind and solar power, big hydropower plants and other sources of electricity that do not generate carbon dioxide.

Utility-scale solar and wind electricity increased from 3 per cent in 2010 to 18 per cent in 2017 in California, exceeding prior state targets, largely because solar prices have dropped sharply in recent years.

Being open to a wide range of technologies makes meeting the 2045 target easier and allowed State Senator Kevin de Leon, the original bill’s author, to amass broad support for the bill.

Where things stood in 2017

About 56 per cent of the power California generated in 2017 came from sources that don’t emit carbon. That puts it more than halfway toward this new goal by 2045.

However, the Diablo Canyon plant, California’s last nuclear power station, is slated for decommissioning by 2025, and no other reactors are in the works. This closure would eliminate the 8.7 per cent of the state’s carbon-free power that came from nuclear energy.

Nearly all of the remaining 44 per cent of the state’s electricity is currently generated by burning natural gas, and virtually none comes from coal. Going completely zero-carbon would require phasing out the state’s natural gas power plants.

On top of wind and solar energy, other generation options include geothermal, small nuclear reactors and carbon dioxide sequestration.

One quirk about this legislation is that it deals only with utility-scale power. It would not preclude private electricity-generation facilities such as the diesel generator a farmer might use to pump water. Nor would it count the power generated by a homeowner’s rooftop solar panels.

When the sun shines

One complication is that the state’s mix of energy sources can vary a great deal, even from one hour to the next.

Consider what happened on 8 April 2018, for example. It was a generally sunny and windy Sunday, with relatively low electricity demand. At night, about 40 per cent of electricity was generated from renewable sources. But around noon that day, more than 80 per cent came from renewable sources including large-scale hydropower.

If the electricity generated from these renewable sources is approximately doubled, as I estimate is necessary to meet the 2045 target, the power available in the middle of the day would greatly exceed the demand for electricity at that time.

This challenge shifts throughout the year.

On 24 and 25 July, Californians were asked to voluntarily use less electricity between 5 p.m. and 9 p.m. to avoid an outage because of hot weather. Prices spiked by more than a factor of 10, helping to keep demand within the supply.

On those days, renewably sourced electricity never met half of the demand for power.

Balancing act

Due to this degree of variability, relying heavily on renewable energy will require ample energy storage and big investments in grid-based technology.

Today, the expected demand for electricity is balanced by the Independent System Operator, an entity that controls the flow of electricity on the grid and selects the lowest-priced sources of electricity available.

Pumped hydro storage, electricity generated from water pumped to a reservoir, is the state’s most common form of storage today. While limited to locations with large dams, the amount of energy stored this way could be increased in California, as recently proposed for Hoover Dam.

Big lithium ion batteries are becoming more affordable and are now beginning to be deployed on the utility scale. As battery and solar prices drop, it may become attractive to disconnect from the grid and use electricity generated by a solar system and stored by a battery.

Lower battery costs are also spurring the sales of more electric vehicles. Ideally, these vehicles could be charged at times when electricity is plentiful and cheap. By 2045, I believe they could be helping make the grid more stable.

Other options are becoming available. One example is utility-scale compressed air storage, where energy is stored as pressurised air.

And there is growing interest in solar thermal plants, which generate electricity from sunlight’s heat and use high-temperature storage to continue generating electricity after the sun sets.

The University of California Merced and many other wholesale electricity customers are saving money by using thermal storage. They chill water when rates are low and use the chilled water for air conditioning when electricity prices are high.


Wiggle room

Because California’s new law does not require that every watt be generated within California’s borders, utilities could keep buying electricity from nearby states, as long as they verify its origins are in keeping with the new law’s requirements.

And because the law does not define “zero-carbon,” it provides flexibility in how the state can meet this new target.

For example, California would allow the continued operation of natural gas plants when their output is coupled with purchase of renewable energy certificates, credits issued for the generation of renewable electricity that may be sold, from a utility that generates solar or wind power.

These credits arise through several kinds of arrangements. Perhaps the most common is through rooftop solar systems. Small-scale solar energy supplied about 5 per cent of California’s electricity in 2017. It is likely to grow because of California’s mandate for solar panels on most new homes, starting in 2020.

In assessing whether the goal of going zero-carbon by 2045 is realistic or not, it is worth considering that solar energy has grown for years at a pace that far exceeded projections: thanks to technological progress, government policies like California’s new law, market forces and the public’s demand for renewable energy.

The Conversation

Sarah Kurtz, Professor of Materials Science and Engineering, University of California, Merced.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

 
 
 
 

There isn’t a war on the motorist. We should start one

These bloody people. Image: Getty.

When should you use the horn on a car? It’s not, and anyone who has been on a road in the UK in living memory will be surprised to hear this, when you are inconvenienced by traffic flow. Nor is it when you are annoyed that you have been very slightly inconvenienced by another driver refusing to break the law in a manner that is objectively dangerous, but which you perceive to be to your advantage.

According to the Highway Code:

“A horn should only be used when warning someone of any danger due to another vehicle or any other kind of danger.”

Let’s be frank: neither you nor I nor anyone we have ever met has ever heard a horn used in such a manner. Even those of us who live in or near places where horns perpetually ring out due to the entitled sociopathy of most drivers. Especially those of us who live in or near such places.

Several roads I frequently find myself pushing a pram up and down in north London are two way traffic, but allow parking on both sides. This being London that means that, in practice, they’re single track road which cars can enter from both ends.

And this being London that means, in practice, that on multiple occasions every day, men – it is literally always men – glower at each other from behind the steering wheels of needlessly big cars, banging their horns in fury that circumstances have, usually through the fault of neither of them, meant they are facing each other on a de facto single track road and now one of them is going to have to reverse for a metre or so.

This, of course, is an unacceptable surrender as far as the drivers’ ego is concerned, and a stalemate seemingly as protracted as the cold war and certainly nosier usually emerges. Occasionally someone will climb out of their beloved vehicle and shout and their opponent in person, which at least has the advantages of being quieter.

I mentioned all this to a friend recently, who suggested that maybe use of car horns should be formally restricted in certain circumstances.

Ha ha ha. Hah.

The Highway Code goes on to say -

“It is illegal to use a horn on a moving vehicle on a restricted road, a road that has street lights and a 30 mph limit, between the times of 11:30 p.m. and 07:00 a.m.”

Is there any UK legal provision more absolutely and comprehensively ignored by those to whom it applies? It might as well not be there. And you can bet that every single person who flouts it considers themselves law abiding. Rather than the perpetual criminal that they in point of fact are.


In the 25 years since I learned to drive I have used a car horn exactly no times, despite having lived in London for more than 20 of them. This is because I have never had occasion to use it appropriately. Neither has anyone else, of course, they’ve just used it inappropriately. Repeatedly.

So here’s my proposal for massively improving all UK  suburban and urban environments at a stroke: ban horns in all new cars and introduce massive, punitive, crippling, life-destroying fines for people caught using them on their old one.

There has never been a war on motorists, despite the persecution fantasies of the kind of middle aged man who thinks owning a book by Jeremy Clarkson is a substitute for a personality. There should be. Let’s start one. Now.

Phase 2 will be mandatory life sentences for people who don’t understand that a green traffic light doesn’t automatically mean you have right of way just because you’re in a car.

Do write in with your suggestions for Phase 3.