Power supply should meet summer demand

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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BC Hydro Review Phase 2 Recommendations advance affordable electricity rates, clean energy adoption, electrification, and demand response, supporting heat pumps, EV charging, and low-income programs to cut emissions and meet CleanBC climate targets.

Key Points

Policies to keep rates affordable and accelerate clean electrification via heat pump, EV, and demand response incentives.

✅ Optional rates, heat pump and EV charging incentives

✅ Demand response via controllable devices lowers peak loads

✅ Expanded support for lower-income customers and affordability

The Province and BC Hydro have released recommendations from Phase 2 of the BC Hydro Review to keep rates affordable, including through a provincial rate freeze initiative that supported households, and encourage greater use of clean, renewable electricity to reduce emissions and achieve climate targets.

“Keeping life affordable for people is a key priority of our government,” said Bruce Ralston, Minister of Energy, Mines and Low Carbon Innovation. “Affordable electricity rates not only help British Columbians, they help ensure the price of electricity remains competitive with other forms of energy, supporting the transition away from fossil fuels to clean electricity in our homes and buildings, vehicles and businesses.”

While affordable rates have always been important to BC Hydro customers, amid proposals such as a modest rate increase under review, expectations are also changing as customers look to have more choice and control over their electricity use and opportunities to save money.

Guided by input from a panel of external energy industry experts, government and BC Hydro have developed recommendations under Phase 2 of the BC Hydro Review to reduce electricity costs for individuals and businesses, even as a 3.75% increase has been discussed, as envisioned by the CleanBC climate strategy. This is also in alignment with TogetherBC, the Province’s poverty reduction strategy, and its guiding principle of affordability.

“As we promote increased use of electricity in B.C. to achieve our climate targets, we need to continue to focus on keeping electricity rates affordable, especially for lower-income families,” said Nicholas Simons, Minister of Social Development and Poverty Reduction. “Through the BC Hydro Review, and continuing engagement with stakeholders and organizations to follow, we are committed to finding ways to keep rates affordable, so everyone has access to the benefits of B.C.’s clean, reliable electricity.”

Recommendations include having BC Hydro consider providing more support for lower-income BC Hydro customers, informed by a recent surplus report that highlighted funding opportunities. These include incentives and exploring optional rates for customers to adopt electric heat pumps, and facilitating customer adoption of controllable energy devices that provide BC Hydro the ability to offer incentives in return for helping to manage a customer’s electricity use. 

Electrification of B.C.’s economy helps customers reduce their carbon footprint and supports the Province’s CleanBC climate strategy, and is an important part of keeping electricity affordable even amid higher BC Hydro rates in recent periods. As more customers make the switch from fossil fuels to using clean electricity in their homes, vehicles and businesses, BC Hydro’s electricity sales will increase, providing more revenue that helps keep rates affordable for everyone.

“We’re making the transition to a cleaner future more affordable for people and businesses across British Columbia through our CleanBC plan,” said George Heyman, Minister of Environment and Climate Change Strategy. “By working with BC Hydro and other partners, we’re making sure everyone has access to clean, affordable electricity to power technologies like high-efficiency heat pumps and electric vehicles that will reduce harmful pollution and improve our homes, buildings and communities.”

Chris O’Riley, president and CEO, BC Hydro, said: “Given the impact of COVID-19 on British Columbians, affordability is more important than ever. That’s why we are committed to continuing to keep rates affordable and offering customers more options that allow them to save on their bills while using clean electricity.”

In July 2021, the Province announced a first set of recommendations from Phase 2 of the BC Hydro Review amid a 3% rate increase approved by regulators. The next announcement from Phase 2 will include recommendations to increase the number of electric vehicles on the road.

In addition, as part of the Draft Action Plan to advance the Declaration on the Rights of Indigenous Peoples Act, the Province is proposing to engage with Indigenous peoples to identify and support new clean energy opportunities related to CleanBC, the BC Hydro Review and the British Columbia Utilities Commission Indigenous Utilities Regulation Inquiry, and to consider lessons from Ontario's hydro policy experiences as appropriate.

B.C. is the cleanest electricity-generation jurisdiction in western North America, with an average of 98% of its electricity generation coming from clean or renewable resources.

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Tesla Electric UK Expansion signals retail energy entry, leveraging Powerwall VPPs for grid services, dynamic pricing, and energy trading, building on Texas success and Octopus Energy ties to buy and sell electricity automatically.

Key Points

Tesla's plan to launch Tesla Electric in the UK, using Powerwall VPPs to retail energy, trade power, and hedge peaks.

✅ Retail energy model built on Powerwall VPP aggregation

✅ Automated buy-sell arbitrage with dynamic pricing

✅ Leverages prior UK approval and Octopus Energy ties

According to a new job posting, Tesla Electric, Tesla’s new electric utility division, is preparing to expand in the United Kingdom as regions such as California grid planners look to electric vehicles for stability to manage demand.

Late last year, after gaining experience through its virtual power plants (VPPs), including response during California blackouts that pressured the grid, Tesla took things a step further with the launch of “Tesla Electric.”

Instead of reacting to specific “events” and providing services to your local electric utilities through demand response programs, as Tesla Powerwall owners have done in VPPs in California, Tesla Electric is actively and automatically buying and selling electricity for Tesla Powerwall owners – providing a buffer against peak prices.

The company is essentially becoming an energy retailer, aligning with a major future for its energy business envisioned by leadership.

Tesla Electric is currently only available to Powerwall owners in Texas, but the company has plans to expand its products through this new division.

We recently reported on Tesla Electric customers in Texas making as much as $150 a day selling electricity back to the grid through the program.

Now Tesla is looking to expand Tesla Electric to the UK, where grid capacity for rising EV demand remains a key consideration.

The company has listed a new job posting for a role called “Head of Operations, Tesla Electric – Retail Energy.”

This has been in the works for a while now. Tesla used to have a partnership with Octopus Energy in the UK for special electricity rates for its owners, during a period when UK EV inquiries surged amid a fuel supply crisis, but it seemed to be a stepping stone before it would itself become an energy provider in the market.

In 2020, Tesla was officially approved as an electricity retailer in the UK. Now it looks like Tesla is going to use this approval with the launch of Tesla Electric.
 

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California Governor Gavin Newsom vetoed a bill aimed at expanding load flexibility in state grid planning, citing conflicts with California’s resource adequacy framework and concerns over grid reliability and energy planning uncertainty.

Why has Newsom vetoed the Bill to Codify Load Flexibility?

Governor Gavin Newsom’s veto blocks legislation that would have required the California Energy Commission to incorporate load flexibility into the state’s energy planning and policy framework, a move that has stirred debate across the clean energy sector.

✅ Argues the bill conflicts with California’s existing Resource Adequacy system

✅ Draws backlash from clean energy and grid modernization advocates

✅ Exposes ongoing tension over how to manage renewable integration and demand response

California Governor Gavin Newsom has vetoed Assembly Bill 44, which would have required the California Energy Commission to evaluate and incorporate load management mechanisms into the state’s energy planning process. The move drew criticism from clean energy advocates who say it undermines efforts to strengthen grid reliability and reduce costs.

The bill directed the commission to adopt “upfront technical requirements and load modification protocols” that would allow load-serving entities to adjust their electrical demand forecasts. Proponents viewed this as a way to modernize California’s grid management, and to explore a revamp of electricity rates to help clean the grid, making it more responsive to demand fluctuations and renewable energy variability.

In his veto statement, Newsom said the bill was incompatible with existing energy planning frameworks, even as a looming electricity shortage remains a concern. “While I support expanding electric load flexibility, this bill does not align with the California Public Utility Commission’s Resource Adequacy framework,” he said. “As a result, the requirements of this bill would not improve electric grid reliability planning and could create uncertainty around energy resource planning and procurement processes.”

Newsom’s decision comes shortly after he signed a broad package of energy legislation that set the stage for a regional Western electricity market and extended the state’s cap-and-trade program. However, that legislative package did not include continued funding for several key grid reliability programs — including what advocates have called the world’s largest virtual power plant, a distributed network of connected devices that can balance electricity demand in real time.

Clean energy supporters saw AB 44 as a crucial step toward integrating these distributed energy resources into long-term grid planning. “With Assembly Bill 44 being vetoed, the state has missed a huge opportunity to advance common-sense policy that would have lowered costs, strengthened the grid, and unlocked the full potential of advanced energy,” said Edson Perez, California lead at Advanced Energy United.

Perez added that the setback increases pressure on lawmakers to take stronger action in the next legislative session. “The pressure is on next session to ensure that California is using all tools in its policy toolbox to build critically needed infrastructure, strengthen the grid, and bring costs down,” he said.

California’s growing use of demand response programs and virtual power plants has been central to its strategy for managing grid stress during heat waves and wildfire seasons. These systems allow utilities and customers to temporarily reduce or shift energy use, helping to prevent blackouts and reduce the need for fossil-fuel peaker plants during peak demand.

A recent report by the Brattle Group found that California’s taxpayer-funded virtual power plant could save ratepayers $206 million between 2025 and 2028 while reducing reliance on gas generation. The study, commissioned by Sunrun and Tesla Energy, highlighted the potential for flexible load management to improve both grid reliability and reduce costs, even as regulators weigh whether the state needs more power plants to ensure reliability.

Despite these findings, Newsom’s veto signals continued tension between state policymakers and clean energy advocates over how best to modernize California’s power grid. While the governor has prioritized large-scale renewable development and regional market integration, critics argue that California’s climate policy choices risk exacerbating reliability challenges and that failing to codify load flexibility could slow progress toward a more adaptive, resilient, and affordable clean energy future.

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Polycrystalline Tin Selenide Thermoelectrics enable waste heat recovery with ZT 3.1, matching single crystals while cutting costs, powering greener car engines, industrial furnaces, and thermoelectric generators via p-type and emerging n-type designs.

Key Points

Low-cost tin selenide devices that turn waste heat into power, achieving ZT 3.1 and enabling p-type and n-type modules.

✅ Oxygen removal prevents heat-leaking tin oxide grain skins.

✅ Polycrystalline ingots match single-crystal ZT 3.1 at lower cost.

✅ N-type tin selenide in development to pair with p-type.

So-called thermoelectric generators turn waste heat into electricity without producing greenhouse gas emissions, providing what seems like a free lunch. But despite helping power the Mars rovers, the high cost of these devices has prevented their widespread use. Now, researchers have found a way to make cheap thermoelectrics that work just as well as the pricey kind. The work could pave the way for a new generation of greener car engines, industrial furnaces, and other energy-generating devices.

“This looks like a very smart way to realize high performance,” says Li-Dong Zhao, a materials scientist at Beihang University who was not involved with the work. He notes there are still a few more steps to take before these materials can become high-performing thermoelectric generators. However, he says, “I think this will be used in the not too far future.”

Thermoelectrics are semiconductor devices placed on a hot surface, like a gas-powered car engine or on heat-generating electronics using thin-film converters to capture waste heat. That gives them a hot side and a cool side, away from the hot surface. They work by using the heat to push electrical charges from one to the other, a process of turning thermal energy into electricity that depends on the temperature gradient. If a device allows the hot side to warm up the cool side, the electricity stops flowing. A device’s success at preventing this, as well as its ability to conduct electrons, feeds into a score known as the figure of merit, or ZT.

 Over the past 2 decades, researchers have produced thermoelectric materials with increasing ZTs, while related advances such as nighttime solar cells have broadened thermal-to-electric concepts. The record came in 2014 when Mercouri Kanatzidis, a materials scientist at Northwestern University, and his colleagues came up with a single crystal of tin selenide with a ZT of 3.1. Yet the material was difficult to make and too fragile to work with. “For practical applications, it’s a non-starter,” Kanatzidis says.

So, his team decided to make its thermoelectrics from readily available tin and selenium powders, an approach that, once processed, makes grains of polycrystalline tin selenide instead of the single crystals. The polycrystalline grains are cheap and can be heated and compressed into ingots that are 3 to 5 centimeters long, which can be made into devices. The polycrystalline ingots are also more robust, and Kanatzidis expected the boundaries between the individual grains to slow the passage of heat. But when his team tested the polycrystalline materials, the thermal conductivity shot up, dropping their ZT scores as low as 1.2.

In 2016, the Northwestern team discovered the source of the problem: an ultrathin skin of tin oxide was forming around individual grains of polycrystalline tin selenide before they were pressed into ingots. And that skin acted as an express lane for the heat to travel from grain to grain through the material. So, in their current study, Kanatzidis and his colleagues came up with a way to use heat to drive any oxygen away from the powdery precursors, leaving pristine polycrystalline tin selenide, whereas other devices can generate electricity from thin air using ambient moisture.

The result, which they report today in Nature Materials, was not only a thermal conductivity below that of single-crystal tin selenide but also a ZT of 3.1, a development that echoes nighttime renewable devices showing electricity from cold conditions. “This opens the door for new devices to be built from polycrystalline tin selenide pellets and their applications to be explored,” Kanatzidis says.

Getting through that door will still take some time. The polycrystalline tin selenide the team makes is spiked with sodium atoms, creating what is known as a “p-type” material that conducts positive charges. To make working devices, researchers also need an “n-type” version to conduct negative charges.

Zhao’s team recently reported making an n-type single-crystal tin selenide by spiking it with bromine atoms. And Kanatzidis says his team is now working on making an n-type polycrystalline version. Once n-type and p-type tin selenide devices are paired, researchers should have a clear path to making a new generation of ultra-efficient thermoelectric generators. Those could be installed everywhere from automobile exhaust pipes to water heaters and industrial furnaces to scavenge energy from some of the 65% of fossil fuel energy that winds up as waste heat. 

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Cerro Dominador CSP Plant delivers 110MW concentrated solar power in Chile's Atacama Desert, with 10,600 heliostats, 17.5-hour molten salt storage, and 24/7 dispatchable energy; built by Acciona and Abengoa within a 210MW complex.

Key Points

A 110MW CSP solar-thermal plant in Chile with heliostats and 17.5h molten salt storage, delivering 24/7 dispatchable clean power.

✅ 110MW CSP with 17.5h molten salt for 24/7 dispatch

✅ 10,600 heliostats; part of a 210MW hybrid CSP+PV complex

✅ Built by Acciona and Abengoa; first of its kind in LatAm

A consortium formed by Spanish groups Abengoa and Acciona, as Spain's renewable sector expands with Enel's 90MW wind build activity, has signed a contract to complete the construction of the 110MW Cerro Dominador concentrated solar power (CSP) plant in Chile.

The consortium received notice to proceed to build the solar-thermal plant, which is part of the 210MW Cerro Dominador solar complex.

Under the contract, Acciona, which has 51% stake in the consortium and recently launched a 280 MW Alberta wind farm, will be responsible for building the plant while Abengoa will act as the technological partner.

Expected to be the first of its kind in Latin America upon completion, the plant is owned by Cerro Dominador, which in turn is owned by funds managed by EIG Global Energy Partners.

The project will add to a Abengoa-built 100MW PV plant, comparable to California solar projects in scope, which was commissioned in February 2018, to form a 210MW combined CSP and PV complex.

Spread across an area of 146 hectares, the project will feature 10,600 heliostats and will have capacity to generate clean and dispatachable energy for 24 hours a day using its 17.5 hours of molten salt storage technology, a field complemented by battery storage advances.

Expected to prevent 640,000 tons of CO2 emission, the plant is located in the commune of María Elena, in the Atacama Desert, in the Antofagasta Region.

“In total, the complex will avoid 870,000 tons of carbon dioxide emissions into the atmosphere every year and, in parallel with Enel's 450 MW U.S. wind operations, will deliver clean energy through 15-year energy purchase agreements with distribution companies, signed in 2014.

“The construction of the solarthermal plant of Cerro Dominador will have an important impact on local development, with the creation of more than 1,000 jobs in the area during its construction peak, and that will be priority for the neighbors of the communes of the region,” Acciona said in a statement.

The Cerro Dominador plant represents Acciona’s fifth solar thermal plant being built outside of Spain. The firm has constructed 10 solarthermal plants with total installed capacity of 624MW.

Acciona has been operating in Chile since 1993. The company, through its Infrastructure division, executed various construction projects for highways, hospitals, hydroelectric plants and infrastructures for the mining sector.

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