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California Renewable Energy Curtailment highlights grid congestion, midday solar peaks, limited battery storage, and market constraints, with WEIM participation and demand response programs proposed to balance supply-demand and reduce wasted solar and wind generation.

Key Points

It is the deliberate reduction of solar and wind output when grid limits or low demand prevent full integration.

✅ Grid congestion restricts transmission capacity

✅ Midday solar peaks exceed demand, causing surplus

✅ Storage, WEIM, and demand response mitigate curtailment

California has long been a leader in renewable energy adoption, achieving a near-100% renewable milestone in recent years, particularly in solar and wind power. However, as the state continues to expand its renewable energy capacity, it faces a growing challenge: the curtailment of excess solar and wind energy. Curtailment refers to the deliberate reduction of power output from renewable sources when the supply exceeds demand or when the grid cannot accommodate the additional electricity.

Increasing Curtailment Trends

Recent data from the U.S. Energy Information Administration (EIA) highlights a concerning upward trend in curtailments in California. In 2024, the state curtailed a total of 3,102 gigawatt-hours (GWh) of electricity generated from solar and wind sources, surpassing the 2023 total of 2,660 GWh. This represents a 32.4% increase from the previous year. Specifically, 2,892 GWh were from solar, and 210 GWh were from wind, marking increases of 31.2% and 51.1%, respectively, compared to the first nine months of 2023.

Causes of Increased Curtailment

Several factors contribute to the rising levels of curtailment:

1. Grid Congestion: California's transmission infrastructure has struggled to keep pace with the rapid growth of renewable energy sources. This congestion limits the ability to transport electricity from generation sites to demand centers, leading to curtailment.
   
   

2. Midday Solar Peaks: Amid California's solar boom, solar energy production typically peaks during the midday when electricity demand is lower. This mismatch between supply and demand results in excess energy that cannot be utilized, necessitating curtailment.
   
   

3. Limited Energy Storage: While battery storage technologies are advancing, California's current storage capacity is insufficient to absorb and store excess renewable energy for later use. This limitation exacerbates curtailment issues.
   
   

4. Regulatory and Market Constraints: Existing market structures and regulatory frameworks may not fully accommodate the rapid influx of renewable energy, leading to inefficiencies and increased curtailment.

Economic and Environmental Implications

Curtailment has significant economic and environmental consequences. For renewable energy producers, curtailed energy represents lost revenue and undermines the economic viability of new projects. Environmentally, curtailment means that clean, renewable energy is wasted, and the grid may rely more heavily on fossil fuels to meet demand, counteracting the benefits of renewable energy adoption.

Mitigation Strategies

To address the rising curtailment levels, California is exploring several strategies aligned with broader decarbonization goals across the U.S.:

• Grid Modernization: Investing in and upgrading transmission infrastructure to alleviate congestion and improve the integration of renewable energy sources.
  
  

• Energy Storage Expansion: Increasing the deployment of battery storage systems to store excess energy during peak production times and release it during periods of high demand.
  
  

• Market Reforms: Participating in the Western Energy Imbalance Market (WEIM), a real-time energy market that allows for the balancing of supply and demand across a broader region, helping to reduce curtailment.
  
  

• Demand Response Programs: Implementing programs that encourage consumers to adjust their energy usage patterns, such as shifting electricity use to times when renewable energy is abundant.

Looking Ahead

As California continues to expand its renewable energy capacity, addressing curtailment will be crucial to ensuring the effectiveness and sustainability of its energy transition. By investing in grid infrastructure, energy storage, and market reforms, the state can reduce curtailment levels and make better use of its renewable energy resources, while managing challenges like wildfire smoke impacts on solar output. These efforts will not only enhance the economic viability of renewable energy projects but also contribute to California's 100% clean energy targets by maximizing the use of clean energy and reducing reliance on fossil fuels.

While California's renewable energy sector faces challenges related to curtailment, proactive measures and strategic investments can mitigate these issues, as scientists continue to improve solar and wind power through innovation, paving the way for a more sustainable and efficient energy future.

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California clean electricity accelerates with renewables as solar and wind surge, battery storage strengthens grid resilience, natural gas declines, and coal fades, advancing SB 100 targets, carbon neutrality goals, and affordable, reliable power statewide.

Key Points

California clean electricity is the state's transition to renewable, zero-carbon power, scaling solar, wind and storage.

✅ Solar generation up nearly 20x since 2012

✅ Natural gas power down 20%; coal nearly phased out

✅ Battery storage shifts daytime surplus to evening demand

Data from the California Energy Commission (CEC) highlight California’s continued progress toward building a more resilient grid, achieving 100 percent clean electricity and meeting the state’s carbon neutrality goals.

Analysis of the state’s Total System Electric Generation report shows how California’s power mix has changed over the last decade. Since 2012:

Solar generation increased nearly twentyfold from 2,609 gigawatt-hours (GWh) to 48,950 GWh.

• Wind generation grew by 63 percent.
• Natural gas generation decreased 20 percent.
• Coal has been nearly phased-out of the power mix, and renewable electricity surpassed coal nationally in 2022 as well.

In addition to total utility generation, rooftop solar increased by 10 times generating 24,309 GWh of clean power in 2022. The state’s expanding fleet of battery storage resources also help support the grid by charging during the day using excess renewable power for use in the evening.

“This latest report card showing how solar energy boomed as natural gas powered electricity experienced a steady 20 percent decline over the last decade is encouraging,” said CEC Vice Chair Siva Gunda. “Even as climate impacts become increasingly severe, California remains committed to transitioning away from polluting fossil fuels and delivering on the promise to build a future power grid that is clean, reliable and affordable.”

Senate Bill 100 (2018) requires 100 percent of California’s electric retail sales be supplied by renewable and zero-carbon energy sources by 2045. To keep the state on track, last year Governor Gavin Newsom signed SB 1020, establishing interim targets of 90 percent clean electricity by 2035 and 95 percent by 2040.

The state monitors progress through the Renewables Portfolio Standard (RPS), which tracks the power mix of retail sales, and regional peers such as Nevada's RPS progress offer useful comparison. The latest data show that in 2021 more than 37 percent of the state’s electricity came from RPS-eligible sources such as solar and wind, an increase of 2.7 percent compared to 2020. When combined with other sources of zero-carbon energy such as large hydroelectric generation and nuclear, nearly 59 percent of the state’s retail electricity sales came from nonfossil fuel sources.

The total system electric generation report is based on electric generation from all in-state power plants rated 1 megawatt (MW) or larger and imported utility-scale power generation. It reflects the percentage of a specific resource compared to all power generation, not just retail sales. The total system electric generation report accounts for energy used for water conveyance and pumping, transmission and distribution losses and other uses not captured under RPS.

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UK Peak Power Prices surged as low wind speeds forced National Grid to rely on gas-fired plants and coal generation, amid soaring wholesale gas prices and weak wind generation during the energy crisis.

Key Points

UK Peak Power Prices are electricity costs at peak hours, driven by wind output, gas reliance, and market dynamics.

✅ Spikes when wind generation drops and demand rises.

✅ Driven by gas-fired plants, coal backup, and wholesale gas prices.

✅ Moderate as wind output recovers and interconnectors supply.

Low wind speeds pushed peak hour power prices to the second highest level for at least three years on Monday, a move consistent with UK electricity prices hitting a 10-year high earlier this year, as Britain’s grid was forced to increase its reliance on gas-fired power plants and draw on coal generation.

Calm weather this year has exacerbated the energy price crisis in the UK, as gas-fired power stations have had to pick up the slack from wind farms. Energy demand has surged as countries open up from pandemic restrictions, which together with lower supplies from Russia to western Europe, has sent wholesale gas prices soaring.

Power prices in the UK for the peak evening period between 5pm and 6pm on Monday surpassed £2,000 per megawatt hour, only the second time they have exceeded that level in recent years.

This was still below the levels reached at the height of the gas price crisis in mid-September, when they hit £2,500/MWh, according to the energy consultancy Cornwall Insight, whose records date back to 2018.

Low wind speeds were the main driver behind Monday’s price spike, although expectations of a pick-up in wind generation on Tuesday, after recent record wind generation days, should push them back down to similar levels seen in recent weeks, analysts said.

Despite the expansion of renewables, such as wind and solar, over the past decade, with instances of wind leading the power mix in recent months, gas remains the single biggest source of electricity generation in Britain, typically accounting for nearly 40 per cent of output.

At lunchtime on Monday, gas-fired power plants were producing nearly 55 per cent of electricity, while coal accounted for 3 per cent, reflecting more power from wind than coal in 2016 milestones. Britain’s wind farms were contributing 1.67 gigawatts or just over 4 per cent, according to data from the Drax Electrics Insights website. Over the past 12 months, wind farms have produced 21 per cent of the UK’s electricity on average.

National Grid, which manages the UK’s electricity grid, has been forced on a number of occasions in recent months to ask coal plants to fire up to help offset the loss of wind generation, after issuing a National Grid short supply warning to the market. The government announced in June that it planned to bring forward the closure of the remaining coal stations to the end of September 2024.

Ministers also committed this year to making Britain’s electricity grid “net zero carbon” by 2035, and milestones such as when wind was the main source underline the transition, although some analysts have pointed out that would not signal the end of gas generation.

Since the start of the energy crisis in August, 20 energy suppliers have gone bust as they have struggled to secure the electricity and gas needed to supply customers at record wholesale prices, with further failures expected in coming weeks.

Phil Hewitt, director of the consultancy EnAppSys, said Monday’s high prices would further exacerbate pressures on those energy suppliers that do not have adequate hedging strategies. “This winter is a good time to be a generator,” he added.

Energy companies including Orsted of Denmark and SSE of the UK have reported some of the lowest wind speeds for at least two decades this year, even though record output during Storm Malik highlighted the system's volatility.

According to weather modelling group Vortex, the strength of the wind blowing across northern Europe has fallen by as much as 15 per cent on average in places this year, which some scientists suggest could be due to climate change.
 

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Alberta Electricity Rate Cap stays despite carbon tax repeal, keeping the Regulated Rate Option at 6.8 cents/kWh. Levy funds cover market gaps as the UCP reviews NDP policies to maintain affordable utility bills.

Key Points

Program capping RRO power at 6.8 cents/kWh, using levy funds to offset market prices while the UCP reviews policy.

✅ RRO cap fixed at 6.8 cents/kWh for eligible customers

✅ Levy funds pay generators when market prices exceed the cap

✅ UCP reviewing NDP policies to ensure affordable rates

Alberta's carbon tax has been cancelled, but a consumer price cap on electricity — which the levy pays for — is staying in place for now.

June electricity rates are due out on Monday, about four days after the new UCP government did away with the carbon charge on natural gas and vehicle fuel.

Part of the levy's revenue was earmarked by the previous NDP government to keep power prices at or below 6.8 cents per kilowatt hour under new electricity rules set by the province.

"The Regulated Rate Option cap of 6.8 cents/kWh was implemented by the previous government and currently remains in effect. We are reviewing all policies put in place by the former government and will make decisions that ensure more affordable electricity rates for job-creators and Albertans," said a spokesperson for Alberta's energy ministry in an emailed statement.

Albertans with regulated rate contracts and all City of Medicine Hat utility customers only pay that amount or less, though some Alberta ratepayers have faced deferral-related arrears.

If the actual market price rises above that, the difference is paid to generators directly from levy funds, a buffer that matters as experts warn prices are set to soar later this year.

The government has paid more than $55 million to utilities over the past year ending in March 2019, due to that electricity price cap being in place.

Alberta Energy says the price gap program will continue, at least for the time being, amid electricity policy changes being considered.

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Hedonistic Sustainability turns Copenhagen's ARC waste-to-energy plant into a public playground, blending ski slope, climbing wall, and trails with carbon-neutral heating, renewables, circular economy design, and green growth for climate action and liveability.

Key Points

A design approach fusing public recreation with clean-energy infrastructure to drive carbon-neutral, livable urban growth.

✅ Waste-to-energy plant doubles as recreation hub

✅ Supports carbon-neutral heating and renewables

✅ Stakeholder-driven, scalable urban climate model

“We call it hedonistic sustainability,” says Jacob Simonsen of the decision to put an artificial ski slope on the roof of the £485m Amager Resource Centre (Arc), Copenhagen’s cutting-edge new waste-to-energy power plant that feeds the city’s district heating network as well. “It’s not just good for the environment, it’s good for life.”

Skiing is just one of the activities that Simonsen, Arc’s chief executive, and Bjarke Ingels, its lead architect, hope will enhance the latest jewel in Copenhagen’s sustainability crown. The incinerator building also incorporates hiking and running trails, a street fitness gym and the world’s highest outdoor climbing wall, an 85-metre “natural mountain” complete with overhangs that rises the full height of the main structure.

In Copenhagen, green transformation goes hand-in-hand with job creation, a growing economy and a better quality of life

Frank Jensen, lord mayor

It’s all part of Copenhagen’s plan to be net carbon-neutral by 2025. Even now, after a summer that saw wildfires ravagethe Arctic Circle and ice sheets in Greenland suffer near-record levels of melt, the goal seems ambitious. In 2009, when the project was formulated, it was positively revolutionary.

“A green, smart, carbon-neutral city,” declared the cover of the climate action plan, aligning with a broader electric planet vision, before detailing the scale of the challenge: 100 new wind turbines; a 20% reduction in both heat and commercial electricity consumption; 75% of all journeys to be by bike, on foot, or by public transport; the biogas-ification of all organic waste; 60,000 sq metres of new solar panels; and 100% of the city’s heating requirements to be met by renewables.

Radical and far-reaching, the scheme dared to rethink the very infrastructure underpinning the city. There’s still not a climate project anywhere else in the world that comes close, even as leaders elsewhere champion a fully renewable grid by 2030.

And, so far, it’s working. CO2 emissions have been reduced by 42% since 2005, and while challenges around mobility and energy consumption remain (new technologies such as better batteries and carbon capture are being implemented, and global calls for clean electricity investment grow), the city says it is on track to achieve its ultimate goal.

More significant still is that Copenhagen has achieved this while continuing to grow in traditional economic terms. Even as some commentators insist that nothing short of a total rethink of free-market economics and corporate structures is required to stave off global catastrophe, the Danish capital’s carbon transformation has happened alongside a 25% growth in its economy over two decades. Copenhagen’s experience will be a model for other world cities as the global energy transition unfolds.

The sentiment that lies behind Arc’s conception as a multi-use public good – “hedonistic sustainability” – is echoed by Bo Asmus Kjeldgaard, former mayor of Copenhagen for the environment and the man originally tasked, back in 2010, with making the plan a reality.

“We combined life quality with sustainability and called it ‘liveability’,” says Kjeldgaard, now CEO of his own climate adaptation company, Greenovation. “We succeeded in building a good narrative around this, one that everybody could believe in.”

The idea was first floated in the late 1990s, when the newly elected Kjeldgaard had a vision of Copenhagen as the environmental capital of Europe. His enthusiasm ran into political intransigence, however, and despite some success, a lack of budget meant most of his work became “just another branding exercise – it was greenwashing”.

We’re such a rich country – change should be easy for us

Claus Nielsen, furniture maker and designer

But after stints as mayor of family and the labour market, and children and young people, he ended up back at environment in 2010 with renewed determination and, crucially, a broader mandate from the city council. “I said: ‘This time, we have to do it right,’” he recalls, “so we made detailed, concrete plans for every area, set the carbon target, and demanded the money and the manpower to make it a reality.”

He brought on board more than 200 stakeholders, from businesses to academia to citizen representatives, and helped them develop 22 specific business plans and 65 separate projects. So far the plan appears on track: there has been a 15% reduction in heat consumption, 66% of all trips in the city are now by bike, on foot or public transport, and 51% of heat and power comes from renewable electricity sources.

The onus placed on ordinary Copenhageners to walk and cycle more, pay higher taxes (especially on cars) and put up with the inconvenience of infrastructure construction has generally been met with understanding and good grace. And while some people remain critical of the fact that Copenhagen airport is not factored into the CO2 calculations – it lies beyond the city’s boundaries – and grumble about precise definitions and formulae, dissent has been rare.

This relative lack of nimbyism and carping about change can, says Frank Jensen, the city’s lord mayor, be traced to longstanding political traditions.

“Caring for the environment and taking responsibility for society in general has been an integral part of the upbringing of many Danes,” he says. “Moreover, there is a general awareness that climate change now calls for immediate, ambitious and collective action.” A 2018 survey by Concito, a thinktank, found that such action was a top priority for voters.

Jensen is keen to stress the cooperative nature of the plan and says “our visions have to be grounded in the everyday lives of people to be politically feasible”. Indeed, involving so many stakeholders, and allowing them to actively help shape both the ends and the means, has been key to the plan’s success so far and the continued goodwill it enjoys. “It’s so important to note that we [the authorities] cannot do this alone,” says Jørgen Abildgaard, Copenhagen’s executive climate programme director.

Many businesses around the world have typically been reluctant to embrace sustainability when a dip in profits or inconvenience might be the result, but not in Copenhagen. Martin Manthorpe, director of strategy, business development and public affairs at NCC, one of Scandinavia’s largest construction and industrial groups, was brought in early on by Abildgaard to represent industry on the municipality’s climate panel, and to facilitate discussions with the wider business community. He thinks there are several reasons why.

“The Danes have a trading mindset, meaning ‘What will I have to sell tomorrow?’ is just as important as ‘What am I producing today?’” he says. “Also, many big Danish companies are still ultimately family-owned, so the culture leans more towards long-term thinking.”

It is, he says, natural for business to be concerned with issues around sustainability and be willing to endure short-term pain: “To do responsible, long-term business, you need to see yourself as part of the larger puzzle that is called ‘society’.”

Furthermore, in Denmark climate change denial is given extremely short shrift. “We believe in the science,” says Anders Haugaard, a local entrepreneur. “Why wouldn’t you? We’re told sustainability brings only benefits and we’ve got no reason to be suspicious.”

“No one would dare argue against the environment,” says his friend Claus Nielsen, a furniture maker and designer. “We’re such a rich country – change should be easy for us.” Nielsen talks about how enlightened his kids are – “my 11-year-old daughter is now a flexitarian ” – and says that nowadays he mainly buys organic; Haugaard doesn’t see a problem with getting rid of petrol cars (the whole country is aiming to be fossil fuel-free by 2050 as the EU electricity use by 2050 is expected to double).

Above all, there’s a belief that sustainability need not make the city poorer: that innovation and “green growth” can be lucrative in and of themselves. “In Copenhagen, green transformation goes hand-in-hand with job creation, a growing economy and a better quality of life,” says Jensen. “We have also shown that it’s possible to combine this transition with economic growth and market opportunities for businesses, and I think that other countries can learn from our example.”

Besides, as Jensen notes, there is little alternative, and even less time: “National states have failed to take enough responsibility, but cities have the power and will to create concrete solutions. We need to start accelerating their implementation – we need to act now.”

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Alberta Hydropower Potential highlights renewable energy, dams, reservoirs, grid flexibility, contrasting wind and solar growth with limited investment, regulatory hurdles, river basin resources, and decarbonization pathways across Athabasca, Peace, and Slave River systems.

Key Points

It is the technical capacity for new hydro in Alberta's river basins to support a more reliable, lower carbon grid.

✅ 42,000 GWh per year developable hydro identified in studies.

✅ Major potential in Athabasca, Peace, and Slave River basins.

✅ Barriers include high capital costs, market design, water rights.

When you think about renewable energy sources on the Prairies, your mind may go to the wind farms in southern Alberta, or even the Travers Solar Project, southeast of Calgary.

Most of the conversation around renewable energy in the province is dominated by advancements in solar and wind power, amid Alberta's renewable energy surge that continues to attract attention. 

But what about Canada's main source of electricity — hydro power?

More than half of Canada's electricity is generated from hydro sources, with 632.2 terawatt-hours produced as of 2019. That makes it the fourth largest installed capacity of hydropower in the world. 

But in Alberta, it's a different story. 

Currently, hydro power contributes between three and five per cent of Alberta's energy mix, while fossil fuels make up about 89 per cent.

According to Canada's Energy Future report from the Canada Energy Regulator, by 2050 it will make up two per cent of the province's electricity generation shares.

So why is it that a province so rich in mountains and rivers has so little hydro power?

Hydro's history in Alberta
Hydro power didn't always make up such a small sliver of Alberta's electricity generation. Hydro installations began in the early 20th century as the province's population exploded. 

Grant Berg looks after engineering for hydro for TransAlta, Alberta's largest producer of hydro power with 17 facilities across the province.

"Our first plant was Horseshoe, which started in 1911 that we formed as Calgary Power," he said. 

"It was really in response to the City of Calgary growing and having some power needs."

Berg said in 1913, TransAlta's second installation, the Kananaskis Plant, started as Calgary continued to grow.

A historical photo of a hydro-electric dam in Kananaskis Alta. taken in 1914.
Hydro power plant in Kananaskis as seen in 1914. (Glenbow Archives)
Some bigger installations were built in the 1920s, including Ghost reservoir, but by mid-century population growth increased.

"Quite a large build out really, I think in response to the growth in Alberta following the war. So through the 1950s really quite a large build out of hydro from there."

By the 1950s, around half of the province's installed capacity was hydro power.

"Definitely Calgary power was all hydro until the 1950s," said Berg. 

Hydro potential in the province 
Despite the current low numbers in hydroelectricity, Alberta does have potential. 

According to a 2010 study, there is approximately 42,000 gigawatt-hours per year of remaining developable hydroelectric energy potential at identified sites. 

An average home in Alberta uses around 7,200 kilowatt-hours of electricity per year, meaning that the hydro potential could power 5.8 million homes each year. 

"This volume of energy could be sufficient to serve a significant amount of Alberta's load and therefore play a meaningful role in the decarbonization of the province's electric system," the Alberta Electric System Operator said in its 2022 Pathways to Net-Zero Emissions report.

Much of that potential lies in northern Alberta, in the Athabasca, Peace and Slave River basins.

The AESO report says that despite the large resource potential, Alberta's energy-only market framework has attracted limited investment in hydroelectric generation. 

Hydro power was once a big deal in Alberta, but investment in the industry has been in decline since the 1950s. Climate change reporter Christy Climenhaga explains why.
So why does Alberta leave out such a large resource potential on the path to net zero?

The government of Alberta responded to that question in a statement. 

"Hydro facilities, particularly large scale ones involving dams, are associated with high costs and logistical demands," said the Ministry of Affordability and Utilities. 

"Downstream water rights for other uses, such as irrigation, further complicate the development of hydro projects."

The ministry went on to say that wind and solar projects have increased far more rapidly because they can be developed at relatively lower cost and shorter timelines, and with fewer logistical demands.

"Sources from wind power and solar are increasingly more competitive," said Jean-Denis Charlebois, chief economist with the Canadian Energy Regulator. 

Hydro on the path to net zero
Hydro power is incredibly important to Canada's grid, and will remain so, despite growth in wind and solar power across the province.

Charlebois said that across Canada, the energy make-up will depend on the province. 

"Canadian provinces will generate electricity in very different ways from coast to coast. The major drivers are essentially geography," he said. 

Charlebois says that in British Columbia, Manitoba, Quebec and Newfoundland and Labrador, hydropower generation will continue to make up the majority of the grid.

"In Alberta and Saskatchewan, we see a fair bit of potential for wind and solar expansion in the region, which is not necessarily the case on Canada's coastlines," he said.

And although hydro is renewable, it does bring its adverse effects to the environment — land use changes, changes in flow patterns, fish populations and ecosystems, which will have to be continually monitored. 

"You want to be able to manage downstream effects; make sure that you're doing all the proper things for the environment," said Ryan Braden, director of mining and hydro at TransAlta.

Braden said hydro power still has a part to play in Alberta, even with its smaller contributions to the future grid. 

"It's one of those things that, you know, the wind doesn't blow or the sun doesn't shine, this is here. The way we manage it, we can really support that supply and demand," he said.

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