Is the sun setting on solar power in Spain?

By Scientific American


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On the outskirts of Seville, Spain, 600 rotating mirrors send shafts of light to a collector atop a soaring 115-meter-tall tower.

Its scalding 250-degree-Celsius steam drives a turbine generating a peak capacity of 11 megawatts (MW) of electricity for the national grid. This "power tower" is the first of nine to be built by Spanish engineering giant Abengoa Solar, which all told will produce enough electricity for 153,000 homes by 2013.

From power towers to parabolic trough plants and from photovoltaic farms to roof-mounted solar panels, solar energy is booming in Spain. This month, Europe's first commercial solar-thermal parabolic trough plant — 24-kilometer curved mirror complex dubbed Andasol that focuses light on collector tubes with synthetic oil bubbling to 400 degrees C — revs up in Andalusia. Vast acres of solar farms using photovoltaics made from semiconductors to convert sunlight to electricity now span southern Spain.

Celebrated ground-mounted photovoltaic (PV) plants include La Magascona and Jumilla with their array of 120,000 modules on 120 single-axis "follow-the-sun" trackers.

Even carmakers want a piece of the Spanish sun. In July General Motors said it will build the world's biggest rooftop solar power station in Spain, carpeting 185,800 square meters of the roof at its Zaragoza automobile plant with 85,000 flexible solar panels. And the 50-megawatt Andasol plant is also the world's largest facility employing molten salts to store renewable energy: 28,500 tons of molten potassium and sodium nitrate salt in two tanks that bank excess solar heat for more than seven hours.

Plentiful sunshine isn't the only reason entrepreneurs and industry have flocked to Spain.

The Spanish advantage includes abundant land, strong demand for air conditioning, mammoth infrastructural firms to fast-track projects, and, most importantly, generous subsidies. The nation's feed-in tariffs guarantee 25 years of up to triple the market price for solar energy, making it the world's hottest solar market, trailing only subsidy-richer Germany as well as the U.S. with its historical lead in developing solar technology.

"Feed-in tariffs shift competition to manufacturers, creating an incentive for innovation," says Wilson Rickerson, a Boston-based energy consultant. "Manufacturers that can produce the most efficient and cost-effective ways of generating energy gain most."

In fact, money committed for Spanish PV projects (mostly ground-based) shot up nearly 500 percent from 2006 to 2007 to a total of $3.45 billion, according to London-based New Energy Finance, a renewable energy market research firm.

But obscuring the light are a few clouds. This month Spain slashed the maximum capacity of solar farms that can claim subsidies from 1,200 MW to just 500 MW. Installed PV capacity has already tripled to 1,500 MW in under a year, should double again by 2010 to 3,000 MW, and more than triple to 10,000 MW by 2020. Spain also cut PV feed-in tariffs by about a third to around 33 eurocents per kilowatt hour. Solar-thermal executives fear the same fate within 24 months as new plants add solar power.

That's led many companies to mull other markets. Though Spain backpedaled on severe cuts after panel makers balked, companies like Energias de Portugal Renovables are pulling out because of profit worries and, in August, BP shelved plans for the world's largest solar panel plant in Spain. Critics have warned that when subsidies dry up, so will solar's appeal.

"PV project developers rushed to Spain because subsidies guaranteed returns well above the cost of generating power," explains Nathaniel Bullard, a solar associate at New Energy Finance. "Cuts will drive developers to other markets with high subsidies."

Companies are already eyeing the area's "Club Med" countries where similar feed-in tariffs exist, such as France, Greece and Italy; swathes of sunny Latin America are a possibility; and the U.S. is the ultimate objective as the world's largest electricity market with abundant potential in its sun-soaked Southwest. Healthy tax credits for solar energy in the U.S., extended for eight years in October are also a draw. Abengoa is already building the world's largest solar plant, 280-MW Solana, in Arizona.

"We've been in Spain since 1999 where 80 percent of our revenues originate because its south has double Germany's sunshine and attractive feed-in tariffs," says Henner Gladen, chief technology officer at solar-thermal firm Solar Millennium. That share should fall as the company's new U.S. projects gain ground. "And China, Australia, the Middle East and Africa are the markets of tomorrow."

Spain is already charging into North Africa, which is bathed in 40 percent more sunlight. With World Bank backing, Abengoa is breaking ground on the first hybrid solar-thermal and natural gas burning power plants in Morocco and Algeria, online by 2010. "With abundant radiation and land in its deserts, our neighbor, North Africa, is this region's Southwest," says Michael Geyer, director of international business development at Abengoa, noting that Algeria already has feed-in tariffs. Solar-thermal plants are also planned for Egypt, Israel, Jordan, Libya and the United Arab Emirates.

Most importantly, the initial African power plants and Spain's solar-thermal test bed pave the way for energy export from planned solar farms in the Sahara Desert across a high-voltage direct current trans-sea line to Europe, pending political will and public funds. French President Nicolas Sarkozy resurrected the idea this year in a Plan Solaire.

Studies show that harnessing just 0.3 percent of the sunshine on North African and Middle Eastern deserts could power those regions and Europe. Optimists, such as Nikolai Ulrich, head of renewables Europe at Germany's Nordbank, foresee energy export from Africa within seven years. Imminent milestones include talks in Algeria and Tunisia for transmission lines to Italy, planned for next year. Spain has an edge, because it has been swapping electricity with Morocco over their own two-way line for about a dozen years.

And Spain's solar revolution at home may only slow — not stall. Spain has ample sun, legislation that calls for solar on all new buildings, and PVs poised to deliver low-cost electricity. "Spain is a leader in CSP [concentrated solar power] and hybrid solar/natural gas systems," says Paolo Frankl, head of renewable energy at the International Energy Agency. "And in Spain I expect a shift from ground-mounted plants to solar installations in industrial sites, buildings and other infrastructure like highways. Competition helps innovation."

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Energy storage poised to tackle grid challenges from rising EVs as mobile chargers bring new flexibility

EV Charging Grid Readiness addresses how rising EV adoption, larger batteries, and fast charging affect electric utilities, using vehicle-to-grid, energy storage, mobile and temporary chargers, and smart charging to mitigate distribution stress.

 

Key Points

Planning and tech to manage EV load growth with V2G, storage and smart charging to avoid overloads on distribution grids.

✅ Lithium-ion costs may drop 60%, enabling new charger models

✅ Mobile and temporary chargers buffer local distribution peaks

✅ Smart charging and V2G defer transformer and feeder upgrades

 

The impacts of COVID-19 likely mean flat electric vehicle (EV) sales this year, but a trio of new reports say the long-term outlook is for strong growth — which means the electric grid and especially state power grids will need to respond.

As EV adoption grows, newer vehicles will put greater stress on the electric grid due to their larger batteries and capacity for faster charging, according to Rhombus Energy Solutions, while a DOE lab finds US electricity demand could rise 38% as EV adoption scales. A new white paper from the company predicts the cost of lithium-ion batteries will drop by 60% over the next decade, helping enable a new set of charging solutions.

Meanwhile, mobile and temporary EV charging will grow from 0.5% to 2% of the charging market by 2030, according to new Guidehouse research. The overall charging market is expected to reach reach almost $16 billion in revenues in 2020 and more than $60 billion by 2030. ​A third report finds long-range EVs are growing their share of the market as well, and charging them could cause stress to electric distribution systems. 

"One can expect that the number of EVs in fleets will grow very rapidly over the next ten years," according to Rhombus' report. But that means many fleet staging areas will have trouble securing sufficient charging capacity as electric truck fleets scale up.

"Given the amount of time it takes to add new megawatt-level power feeds in most cities (think years), fleet EVs will run into a significant 'power crisis' by 2030," according to Rhombus.

"Grid power availability will become a significant problem for fleets as they increase the number of electric vehicles they operate," Rhombus CEO Rick Sander said in a statement. "Integrating energy storage with vehicle-to-grid capable chargers and smart [energy management system] solutions as seen in California grid stability efforts is a quick and effective mitigation strategy for this issue."

Along with energy storage, Guidehouse says a new, more flexible approach to charger deployment enabled by grid coordination strategies will help meet demand. That means chargers deployed by a van or other mobile stations, and "temporary" chargers that can help fleets expand capacity. 

According to Guidehouse, the temporary units "are well positioned to de-risk large investments in stationary charging infrastructure" while also providing charge point networks and service providers "with new capabilities to flexibly supply predictable changes in EV transportation behaviors and demand surges."

"Mobile charging is a bit of a new area in the EV charging scene. It primarily leverages batteries to make chargers mobile, but it doesn't necessarily have to," Guidehouse Senior Research Analyst Scott Shepard told Utility Dive. 

"The biggest opportunity is with the temporary charging format," said Shepard. "The bigger units are meant to be located at a certain site for a period of time. Those units are interesting because they create a little more scale-ability for sites and a little risk mitigation when it comes to investing in a site."

"Utilities could use temporary chargers as a way to provide more resilient service, using these chargers in line with on-site generation," Shepard said.

Increasing rates of EV adoption, combined with advances in battery size and charging rates, "will impact electric utility distribution infrastructure at a higher rate than previously projected," according to new analysis from FleetCarma.

The charging company conducted a study of over 3,900 EVs, illustrating the rapid change in vehicle capabilities in just the last five years. According to FleetCarma, today's EVs use twice as much energy and draw it at twice the power level. The long-range EV has increased as a proportion of new electric vehicle sales from 14% in 2014 to 66% in 2019 in the United States, it found.

Long-range EVs "are very different from older electric vehicles: they are driven more, they consume more energy, they draw power at a higher level and they are less predictable," according to FleetCarma.

Guidehouse analysts say grid modernization efforts and energy storage can help smooth the impacts of charging larger vehicles. 

Mobile and temporary charging solutions can act as a "buffer" to the distribution grid, according to Guidehouse's report, allowing utilities to avoid or defer some transmission and distribution upgrade costs that could be required due to stress on the grid from newer vehicles.

"At a high level, there's enough power and energy to supply EVs with proper management in place," said Shepard. "And in a lot of different locations, those charging deployments will be built in a way that protects the grid. Public fast charging, large commercial sites, they're going to have the right infrastructure embedded."

"But for certain areas of the grid where there is low visibility, there is the potential for grid disruption and questions about whether the UK grid can cope with EV demand," said Shepard. "This has been on the mind of utilities but never realized: overwhelming residential transformers."

As EVs with higher charging and energy capacities are connected to the grid, Shepard said, "you are going to start to see some of those residential systems come under pressure, and probably see increased incidences of having to upgrade transformers." Some residential upgrades can be deferred through smarter charging programs, he added.

 

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Wind turbine firms close Spanish factories as Coronavirus restrictions tighten

Spain Wind Turbine Factory Shutdowns disrupt manufacturing as Vestas, Siemens Gamesa, and Nordex halt Spanish plants amid COVID-19 lockdowns, straining supply chains and renewables projects across Europe, with partial operations and maintenance continuing.

 

Key Points

COVID-19 lockdowns pause Spanish wind factories by Vestas, Siemens Gamesa, and Nordex, disrupting supply chains.

✅ Vestas, Siemens Gamesa, Nordex halt Spanish manufacturing

✅ Service and maintenance continue under safety protocols

✅ Supply chain and project timelines face delays in Europe

 

Europe’s largest wind turbine makers on Wednesday said they had shut down more factories in Spain, a major hub for the continent’s renewables sector, in response to an almost total lockdown in the country to contain the coronavirus outbreak as the Covid-19 crisis disrupts the sector.

Denmark’s Vestas, the world No.1, has suspended production at its two Spanish plants, a spokesman told Reuters, adding that its service and maintenance business was still working. Vestas has also paused manufacturing and construction in India, which is under a nationwide lockdown too, he said, and similar disruptions could stall U.S. utility solar projects this year.

Top rival Siemens Gamesa, known for its offshore wind turbine lineup, suspended production at six Spanish factories on Monday, bringing total closures there to eight, a spokeswoman said.

Four components factories are still partially up and running, at Reinosa on the north coast, Cuenca near Madrid, Mungia and Siguiero, she added.

Germany’s Nordex, the No.8 globally which is 36% owned by Spain’s Acciona, has now shuttered all of its production in Spain, even as new projects like Enel’s 90MW build move ahead, including two nacelle casing factories in Barasoain and Vall d’Uixo, as well as a rotor blade site in Lumbier.

“Production is no longer active,” a spokeswoman said in response to a Reuters query.

The new closures take the number of idled wind power factories on the continent to 19, all in Spain and Italy, the European countries worst hit by the pandemic, with investments at risk across the sector.

Spain is second only to Italy in terms of numbers of coronavirus-related fatalities and restrictions have become even stricter in the country’s third week of lockdown at a time when renewables surpassed fossil fuels for the first time in Europe.

“Some factories have temporarily paused activity as a precautionary step to strengthen sanitary measures within the sites and guarantee full compliance with government recommendations,” industry association WindEurope said, noting that wind power grows in some markets despite the pandemic.

 

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In a record year for clean energy purchases, Southeast cities stand out

Municipal Renewable Energy Procurement surged as cities contracted 3.7 GW of solar and wind, leveraging green tariffs, community solar, and utility partnerships across the Southeast, led by Houston, RMI, and WRI data.

 

Key Points

The process by which cities contract solar and wind via utilities or green tariffs to meet climate goals.

✅ 3.7 GW procured in 2020, nearly 25% year-over-year growth

✅ Houston runs city ops on 500 MW solar, a record purchase

✅ Southeast cities use green tariffs and community solar

 

Cities around the country bought more renewable energy last year than ever before, reflecting how renewables may soon provide one-fourth of U.S. electricity across the grid, with some of the most remarkable projects in the Southeast, according to new data unveiled Thursday.

Even amid the pandemic, about eight dozen municipalities contracted to buy nearly 3.7 gigawatts of mostly solar and wind energy — enough to power more than 800,000 homes. The figure is almost a quarter higher than the year before.

Half of the cites listed as “most noteworthy” in Thursday’s release —  from research groups Rocky Mountain Institute and World Resources Institute — are in the region that stretches from Texas to Washington, D.C. 

Houston stands out for the sheer enormity of its purchase: In July, it began powering city operations entirely from nearly 500 megawatts of solar power — the largest municipal purchase of renewable energy ever in the United States, as renewable electricity surpassed coal nationwide.

The groups also feature smaller deals in North Carolina and Tennessee, achieved through a utility partnership called a green tariff.

“We wanted to recognize that Nashville and Charlotte were really blazing a new trail,” said Stephen Abbott, principal at the Rocky Mountain Institute.

And the nation’s capital shows how renewable energy can be a source of revenue: It’s leasing out its public transit station rooftops for 10 megawatts of community solar.

All of these strategies will be necessary for scores of U.S. cities to meet their ambitious climate goals, researchers believe. An interactive clean energy targets tracker shows all 95 clean energy procurements from the year in detail.


Tracker 
Even before former President Donald Trump promised to remove the United States from the Paris Climate Accord, a lack of federal action on climate left a void that some cities and counties were beginning to fill, as renewables hit a record 28% in a recent month. In 2015, the first year tracked by researchers at the Rocky Mountain Institute and the World Resources Institute, municipalities contracted to buy more than 1 gigawatt of wind, solar and other forms of clean energy. 

But when Trump officially set in motion the withdrawal from the climate agreement, the ranks of municipalities dedicated to 100% clean energy multiplied. Today there are nearly 200 of them. The growth in activity last year reflects, in part, that surge of new pledges.

“It takes a while to get city staff up to speed and understand the options, and create the roadmap and then start executing,” Abbott said. “There is a bit of a lag, but we’re starting to see the impact.”

Even in Houston — one of the earliest to begin procuring renewable energy — there has been a steep learning curve as market forces change and prices drop, including cheaper solar batteries shaping procurement strategies, said Lara Cottingham, Houston’s chief of staff and chief sustainability officer.

No matter how well resourced and educated their staff, cities have to clear a thicket of structural, political and economic challenges to procure renewable energy. Most don’t own their own sources of power. Nearly all face budget constraints. Few have enough land or government rooftops to meet their goals within city limits.

“Cities face a situation where it’s a square peg in a round hole,” Cottingham said.

The hurdles are especially steep in much of the Southeast, where only publicly regulated utilities can sell electricity to retail customers, even large ones such as major cities. That’s where a green tariff regime comes in: Cities can purchase clean energy from a third party, such as a solar company, using the utility as a go-between.

Early last year, Charlotte became the largest city to use such a program, partnering with Duke Energy and two North Carolina solar developers to build a solar farm 50 miles north in Iredell County. At first, the city will pay a premium for the energy, but in the latter half of the 20-year contract, as gas prices rise, it will save money compared to business as usual.

“Over the course of 20 years, it’s projected we would save about $2 million,” Katie Riddle, sustainability analyst with Charlotte, told the Energy News Network last year.

The growing size of projects, innovative partnerships like green tariff programs, and the improving economics all give Abbott hope that renewable energy investments from cities will only grow — even with the Trump presidency over and the country back in the Paris agreement.

And when cities meet their goals for procuring renewable energy for their own operations, they must then turn to an even bigger task: reducing the carbon footprint of every person in their jurisdiction with broader decarbonization strategies and community engagement.

“The city needs to do its part for sure,” said Houston’s Cottingham. “Then we have this challenge of how do we get everyone else to.”

 

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Britain breaks record for coal-free power generation - but what does this mean for your energy bills?

UK Coal-Free Electricity Record highlights rapid growth in renewables as National Grid phases out coal; wind, solar, and offshore projects surge, green tariffs expand, and energy comparison helps consumers switch to cheaper, cleaner deals.

 

Key Points

Britain's longest coal-free run, enabled by renewables, lower demand, and grid shifts for cheaper, greener tariffs.

✅ Record set after two months without coal-fired generation

✅ Renewables outpace fossil fuels; wind and solar dominate

✅ Green tariffs expand; prices at three-year lows

 

On Wednesday 10 June, Britain hit a significant landmark: the UK went for two full months without burning coal to generate power – that's the longest period since the 1880s, following earlier milestones such as a full week without coal power in the recent past.

According to the National Grid, Britain has now run its electricity network without burning coal since midnight on the 9 April. This coal-free period has beaten the country’s previous record of 18 days, six hours and 10 minutes, which was set in June 2019, even though low-carbon generation stalled in 2019 according to analyses.

With such a shift in Britain’s drive for renewables and lower electricity demand following the coronavirus lockdown, as Britain recorded its cleanest electricity during lockdown to date, now may be the perfect time to do an online energy comparison and switch to a cheaper, greener deal.

Only a decade ago, around 40 per cent of Britain’s electricity came from coal generation, but since then the country has gradually shifted towards renewable energy, with the coal share at record lows in the system today. When Britain was forced into lockdown in response to the coronavirus pandemic, electricity demand dropped sharply, and the National Grid took the four remaining coal-fired plants off the network.

Over the past 10 years, Britain has invested heavily in renewable energy. Back in 2010, only 3 per cent of the country's electricity came from wind and solar, and many people remained sceptical. However, now, the UK has the biggest offshore wind industry in the world. Plus, last year, construction of the world’s single largest wind farm was completed off the coast of Yorkshire.

At the same time, Drax – Britain’s biggest power plant – has started to switch from burning coal to burning compressed wooden pellets instead, reflecting the UK's progress as it keeps breaking its coal-free energy record again across the grid. By this time next year, the plant hopes to have phased out coal entirely.

So far this year, renewables have generated more power than all fossil fuels put together, the BBC reports, and the energy dashboard shows the current mix in real time. Renewables have been responsible for 37 per cent of electricity supplied to the network, with wind and solar surpassing nuclear for the first time, while fossil fuels have accounted for 35 per cent. During the same period, nuclear accounted for 18 per cent and imports made up the remaining 10 per cent.

What does this mean for consumers?

As the country’s electricity supply moves more towards renewables, customers have more choice than ever before. Most of the ‘Big Six’ energy companies now have tariffs that offer 100 per cent green electricity. On top of this, specialist green energy suppliers such as Bulb, Octopus and Green Energy UK make it easier than ever to find a green energy tariff.

The good news is that our energy comparison research suggests that green energy doesn’t have to cost you more than a traditional fixed-price energy contract would. In fact, some of the cheapest energy suppliers are actually green companies.

At present, energy bills are at three-year lows, which means that now is the perfect time to switch supplier. As prices remain low and renewables begin to dominate the marketplace, more switchers will be drawn to green energy deals than ever before.

However, if you’re interested in choosing a green energy supplier, make sure that you look at the company's fuel mix. This way, you’ll be able to see whether they are guaranteeing the usage of green energy, or whether they’re just offsetting your usage. All suppliers must report how their energy is generated to Ofgem, so you’ll easily be able to compare providers.

You may find that you pay more for a supplier that generates its own energy from renewables, or pay less if the supplier simply matches your usage by buying green energy. You can decide which option is right for you after comparing the prices.

 

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Ireland goes 25 days without using coal to generate electricity

Ireland Coal-Free Electricity Record: EirGrid reports 25 days without coal on the all-island grid, as wind power, renewables, and natural gas dominated generation, cutting CO2 emissions, with Moneypoint sidelined by market competitiveness.

 

Key Points

It is a 25-day period when the grid used no coal, relying on gas and renewables to reduce CO2 emissions.

✅ 25 days coal-free between April 11 and May 7

✅ Gas 60%, renewables 30% of generation mix

✅ Eurostat: 6.8% drop in Ireland's CO2 emissions

 

The island of Ireland has gone a record length of time without using coal-fired electricity generation on its power system, Britain's week-long coal-free run providing a recent comparator, Eirgrid has confirmed.

The all-island grid operated without coal between April 11th and May 7th – a total of 25 days, it confirmed. This is the longest period of time the grid has operated without coal since the all-island electricity market was introduced in 2007, echoing Britain's record coal-free stretch seen recently.

Ireland’s largest generating station, Moneypoint in Co Clare, uses coal, with recent price spikes in Ireland fueling concerns about dispatchable capacity, as do some of the larger generation sites in Northern Ireland.

The analysis coincides with the European statistics agency, Eurostat publishing figures showing annual CO2 emissions in Ireland fell by 6.8 per cent last year; partly due to technical problems at Moneypoint.

Over the 25-day period, gas made up 60 per cent of the fuel mix, while renewable energy, mainly wind, accounted for 30 per cent, echoing UK wind surpassing coal in 2016 across the market. Coal-fired generation was available during this period but was not as competitive as other methods.

EirGrid group chief executive Mark Foley said this was “a really positive development” as coal was the most carbon intense of all electricity sources, with its share hitting record lows in the UK in recent years.

“We are acutely aware of the challenges facing the island in terms of meeting our greenhouse gas emission targets, mindful that low-carbon generation stalled in the UK in 2019, through the deployment of more renewable energy on the grid,” he added.

Last year 33 per cent of the island’s electricity came from renewable energy sources, German renewables surpassing coal and nuclear offering a parallel milestone, a new record. Coal accounted for 9 per cent of electricity generation, down from 12.9 per cent in 2017.

 

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Was there another reason for electricity shutdowns in California?

PG&E Wind Shutdown and Renewable Reliability examines PSPS strategy, wildfire risk, transmission line exposure, wind turbine cut-out speeds, grid stability, and California's energy mix amid historic high-wind events and supply constraints across service areas.

 

Key Points

An overview of PG&E's PSPS decisions, wildfire mitigation, and how wind cut-out limits influence grid reliability.

✅ Wind turbines reach cut-out near 55 mph, reducing generation.

✅ PSPS mitigates ignition from damaged transmission infrastructure.

✅ Baseload diversity improves resilience during high-wind events.

 

According to the official, widely reported story, Pacific Gas & Electric (PG&E) initiated power shutoffs across substantial portions of its electric transmission system in northern California as a precautionary measure.

Citing high wind speeds they described as “historic,” the utility claims that if it didn’t turn off the grid, wind-caused damage to its infrastructure could start more wildfires.

Perhaps that’s true. Perhaps. This tale presumes that the folks who designed and maintain PG&E’s transmission system are unaware of or ignored the need to design it to withstand severe weather events, and that the Federal Energy Regulatory Commission (FERC) and North American Electric Reliability Corp. (NERC) allowed the utility to do so.

Ignorance and incompetence happens, to be sure, but there’s much about this story that doesn’t smell right—and it’s disappointing that most journalists and elected officials are apparently accepting it without question.

Take, for example, this statement from a Fox News story about the Kincade Fires: “A PG&E meteorologist said it’s ‘likely that many trees will fall, branches will break,’ which could damage utility infrastructure and start a fire.”

Did you ever notice how utilities cut wide swaths of trees away when transmission lines pass through forests? There’s a reason for that: When trees fall and branches break, the grid can still function, and even as the electric rhythms of New York City shifted during COVID-19, operators planned for variability.

So, if badly designed and poorly maintained infrastructure isn’t the reason PG&E cut power to millions of Californians, what might have prompted them to do so? Could it be that PG&E’s heavy reliance on renewable energy means they don’t have the power to send when a “historic” weather event occurs, especially as policymakers weigh the postponed closure of three power plants elsewhere in California?

 

Wind Speed Limits

The two most popular forms of renewable energy come with operating limitations, which is why some energy leaders urge us to keep electricity options open when planning the grid. With solar power, the constraint is obvious: the availability of sunlight. One doesn’t generate solar power at night and energy generation drops off with increasing degrees of cloud cover during the day.

The main operating constraint of wind power is, of course, wind speed, and even in markets undergoing 'transformative change' in wind generation, operators adhere to these technical limits. At the low end of the scale, you need about a 6 or 7 miles-per-hour wind to get a turbine moving. This is called the “cut-in speed.” To generate maximum power, about a 30 mph wind is typically required. But, if the wind speed is too high, the wind turbine will shut down. This is called the “cut-out speed,” and it’s about 55 miles per hour for most modern wind turbines.

It may seem odd that wind turbines have a cut-out speed, but there’s a very good reason for it. Each wind turbine rotor is connected to an electric generator housed in the turbine nacelle. The connection is made through a gearbox that is sized to turn the generator at the precise speed required to produce 60 Hertz AC power.

The blades of the wind turbine are airfoils, just like the wings of an airplane. Adjusting the pitch (angle) of the blades allows the rotor to maintain constant speed, which, in turn, allows the generator to maintain the constant speed it needs to safely deliver power to the grid. However, there’s a limit to blade pitch adjustment. When the wind is blowing so hard that pitch adjustment is no longer possible, the turbine shuts down. That’s the cut-out speed.

Now consider how California’s power generation profile has changed. According to Energy Information Administration data, the state generated 74.3 percent of its electricity from traditional sources—fossil fuels and nuclear, amid debates over whether to classify nuclear as renewable—in 2001. Hydroelectric, geothermal, and biomass-generated power accounted for most of the remaining 25.7 percent, with wind and solar providing only 1.98 percent of the total.

By 2018, the state’s renewable portfolio had jumped to 43.8 percent of total generation, with clean power increasing and wind and solar now accounting for 17.9 percent of total generation. That’s a lot of power to depend on from inherently unreliable sources. Thus, it wouldn’t be at all surprising to learn that PG&E didn’t stop delivering power out of fear of starting fires, but because it knew it wouldn’t have power to deliver once high winds shut down all those wind turbines

 

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