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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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Texas Power Grid Blackouts loom as ERCOT forecasts record air conditioning load, tight reserve margins, peak demand spikes, and rising natural gas prices; heatwaves could trigger brownouts without added solar, storage, and demand response.

Key Points

Texas Power Grid Blackouts are outages when AC-driven peak demand and ERCOT reserves outstrip supply during heatwaves.

✅ ERCOT forecasts record AC load and tight reserve margins.

✅ Coal retirements cut capacity; gas and solar additions lag.

✅ Peak prices, brownouts likely without storage and demand response.

U.S. Air conditioning related electricity usage will break records and may cause blackouts across the U.S. and in Texas this summer. Power grid operators are forecasting that electricity supplies will exceed demands during the summer months.

Most of Texas will face severe electricity shortages because of hot temperatures, air conditioning, and a strong economy, with millions at risk of electricity shut-offs during extreme heat, Bill Magness the president of the Electric Reliability Council of Texas (ERCOT) told the Associated Press. Magness thinks the large numbers people moving to Texas for retirement will increase the demand for air conditioning and electricity use. Retired people are more likely to be home during the day when temperatures are high – so they are more likely to turn up the air conditioner.

Around 50% of all electricity in Texas is used for air conditioning and 100% of homes in Texas have air conditioners, Forbes reported. That means just a few hot days can strain the grid and a heatwave can trigger brownouts and blackouts, in a system with more blackouts than other developed countries on average.

The situation was made worse by Vistra Energy’s decision to close more coal-fired power plants last year, The Austin American Statesman reported. The closed plants; Big Brown, Sadow, and Monticello, generated around 4,100 megawatts (4.1 million watts) of electricity, enough generation capacity to power two million homes, The Waco Herald-Tribune reported.

Texas Electric Grid Might Not Meet Demand

Texas’s grid has never operated without those plants will make this summer a test of its capacity. Texas only has a 6% reserve of electricity that might fall will because of problems like downed lines or a power plant going offline.

A Vistra subsidiary called Luminant has added around 8,000 megawatts of generation capacity from natural-gas burning plants, The Herald-Tribune reported. Luminant also plans to open a giant solar power plant in Texas to increase grid capacity.

The Texas grid already reached peak capacity in May because of unexpectedly high demand and technical problems that reflect more frequent outages in many states, Houston Public Media reported. Grid capacity fell because portions of the system were offline for maintenance.

Some analysts have suggested starting schools after Labor Day to shift peak August demand, potentially easing stress on the grid.

Electricity Reserves are Tight in Texas

Electricity reserves will be very tight on hot summer days in Texas this summer, Magness predicted. When the thermometer rises, people crank up the air conditioner which burns more electricity.

The grid operator ERCOT anticipates that Texas will need an additional 1,600 megawatts of electricity this summer, but record-high temperatures can significantly increase the demand. If everything is running correctly, Texas’s grid can produce up to 78,184 megawatts of electricity.

“The margin between absolute peak power usage and available peak supply is tighter than in years past,” Andrew Barlow, a spokesman for Texas’s Public Utility Commission admitted.

Around 90% of Texas’s grid has enough generating capacity, ERCOT estimated. That means 10% of Texas’s power grid lacks sufficient generating capacity which increases the possibility of blackouts.

Even if the electricity supply is adequate electricity prices can go up in Texas because of higher natural gas prices, Forbes reported. Natural gas prices might go up over the summer because of increased electricity demands. Texas uses between 8% and 9% of America’s natural gas supply to generate electricity for air conditioning in the summer.

Be Prepared For Blackouts This Summer.

Texas’s problems might affect other regions including neighboring states such as Oklahoma, Arkansas, Louisiana, and New Mexico and parts of Mexico, as lawmakers push to connect Texas’s grid to the rest of the nation to improve resilience because those areas are connected to the same grid. Electricity from states like Colorado might be diverted to Texas in case of power shortages there.

Beyond the U.S., Canadian electricity grids are increasingly exposed to harsh weather that can ripple across markets as well.

Home and business owners can avoid summer blackouts by tapping sources of Off-Grid electricity. The two best sources are backup battery storage and solar panels which can run your home or business if the grid runs dry.

If you have family members with health problems who need air conditioning, or you rely on a business or freelance work that requires electricity for income, backup power is vital. Those who need backup electricity for their business should be able to use the expense of installing it as a tax deduction.

Having backup electricity available might be the only way for Texans to keep cool this summer.

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Ontario IESO COVID-19 Control Room Measures detail how essential operators safeguard the electricity grid with split shifts, backup control centres, real-time balancing, deep cleaning, social distancing, and shelter-in-place readiness to maintain reliable power.

Key Points

Measures that protect essential grid operators with split shifts, backup sites, and hygiene to keep power reliable.

✅ Split teams across primary and backup control centres

✅ 12-hour shifts with remote handoffs and deep cleaning

✅ Real-time grid modeling to balance demand and supply

A group of personnel key to keeping Ontario's electricity system functioning may end up locked down in their control centres due to the COVID-19 crisis, according to the head of the province's power operator.

But that has so far proven unnecessary with a change-up in routine, Independent Electricity System Operator CEO Peter Gregg said.

While about 90 per cent of staff were sent to work from home on March 13, another 48 control-room operators deemed essential are still going into work, Gregg said in an interview.

"We identified a smaller cohort of critical operations room staff that need to go in to operate the system out of our control centres," Gregg said. "My biggest concern is to maintain their health, their safety as we rely on them to do this critical work."

Some of the operators manage power demand and supply in real time as Ontario electricity demand shifts, by calling for more or less generation and keeping an eye on the distribution grid, which also allows power to flow to and from Ontario's neighbours. Others do scenario planning and modelling to prepare for changes.

The essential operators have been split into eight teams of six each working 12-hour shifts. The day crew works out of a control centre near Toronto and the night shift out of a backup centre in the city's west end, Gregg said.

"That means that we're not having physical hand-off between control room operators on shift change -- we can do it remotely -- and it also allows us to do deep cleansing," Gregg said. "We're fortunate that the way the room is set up allows us to practice good social distancing."

Should it become necessary, he said, bed, food and other on-site arrangements have been made to allow the operators to stay at their workplaces as a similar agency in New York has done.

"If we do need to shelter these critical employees in place, we've got the ability to do so."

IESO is responsible for ensuring a balance between supply and demand for electricity across the province. Because power cannot be stored, the IESO ensures generators produce enough power to meet peak demand while making sure they don't produce too much.

"You're seeing, obviously, commercial demand drop, some industrial demand drop," Gregg said. "But you're also seeing a shift in the demand curve as well, where normally you have people heading off to work and so residential demand would go down. But obviously with them staying home, you're seeing an increase in residential electricity use across the province."

Some utilities have indicated no cuts to peak rates for self-isolating customers, with Hydro One peak pricing remaining in place for now.

IESO also runs and settles the wholesale electricity markets. Market prices are set based on accepted offers to supply electricity, while programs supporting stable electricity pricing for industrial and commercial users can affect costs against forecast demand.

With the pandemic forcing many businesses to close and people to stay home, and provincial electricity relief for families and small businesses in place, typical power needs fallen about seven per cent at a time of year that would normally see demand soften anyway. It remains to be seen whether, and how much, power needs shift further amid stringent isolation measures and the ongoing economic impact of the outbreak.

Gregg said the operator is constantly modeling different possibilities.

"What we do normally is prepare for all of these sort of emergency scenarios, as reflected in the U.S. grid response coverage, and test and drill for these," he said. "What we're experiencing over the last few weeks is that those drills come in handy because they help us prepare for when the real-time situation actually happens."

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Waste-to-Graphene uses flash joule heating to convert carbon-rich trash into turbostratic graphene for composites, asphalt, concrete, and flexible electronics, delivering scalable, low-cost, high-quality material from food scraps, plastics, and tires with minimal processing.

Key Points

A flash heating method converting waste carbon into turbostratic graphene for scalable, low-cost industrial uses.

✅ Converts food scraps, plastics, and tires into graphene

✅ Produces turbostratic flakes that disperse well in composites

✅ Scalable, low-cost process via flash joule heating

Science doesn’t usually take after fairy tales. But Rumpelstiltskin, the magical imp who spun straw into gold, would be impressed with the latest chemical wizardry. Researchers at Rice University report today in Nature that they can zap virtually any source of solid carbon, from food scraps to old car tires, and turn it into graphene—sheets of carbon atoms prized for applications ranging from high-strength plastic to flexible electronics, and debates over 5G electricity use continue to evolve. Current techniques yield tiny quantities of picture-perfect graphene or up to tons of less prized graphene chunks; the new method already produces grams per day of near-pristine graphene in the lab, and researchers are now scaling it up to kilograms per day.

“This work is pioneering from a scientific and practical standpoint” as it promises to make graphene cheap enough to use to strengthen asphalt or paint, says Ray Baughman, a chemist at the University of Texas, Dallas. “I wish I had thought of it.” The researchers have already founded a new startup company, Universal Matter, to commercialize their waste-to-graphene process, while others are digitizing the electrical system to modernize infrastructure.

With atom-thin sheets of carbon atoms arranged like chicken wire, graphene is stronger than steel, conducts electricity and heat better than copper, and can serve as an impermeable barrier preventing metals from rusting, while advances such as superconducting cables aim to cut grid losses. But since its 2004 discovery, high-quality graphene—either single sheets or just a few stacked layers—has remained expensive to make and purify on an industrial scale. That’s not a problem for making diminutive devices such as high-speed transistors and efficient light-emitting diodes. But current techniques, which make graphene by depositing it from a vapor, are too costly for many high-volume applications. And higher throughput approaches, such as peeling graphene from chunks of the mineral graphite, produce flecks composed of up to 50 graphene layers that are not ideal for most applications.

Graphene comes in many forms. Single sheets, which are ideal for electronics and optics, can be grown using a method called chemical vapor deposition. But it produces only tiny amounts. For large volumes, companies commonly use a technique called liquid exfoliation. They start with chunks of graphite, which is just myriad stacked graphene layers. Then they use acids and solvents, as well as mechanical grinding, to shear off flakes. This approach typically produces tiny platelets each made up of 20 to 50 layers of graphene.

In 2014, James Tour, a chemist at Rice, and his colleagues found they could make a pure form of graphene—each piece just a few layers thick—by zapping a form of amorphous carbon called carbon black with a laser. Brief pulses heated the carbon to more than 3000 kelvins, snapping the bonds between carbon atoms; for comparison, researchers have also generated electricity from falling snow using triboelectric effects. As the cloud of carbon cooled, it coalesced into the most stable structure possible, graphene. But the approach still produced only tiny qualities and required a lot of energy.

Two years ago, Luong Xuan Duy, one of Tour’s graduate students, read that other researchers had created metal nanoparticles by zapping a material with electricity, creating the same brief blast of heat behind the success of the laser graphene approach. “I wondered if I could use that to heat a carbon source and produce graphene,” Duy says. So, he put a dash of carbon black in a clear glass vial and zapped it with 400 volts, similar in spirit to electrical weed zapping approaches in agriculture, for about 200 milliseconds. Initially he got junk. But after a bit of tweaking, he managed to create a bright yellowish white flash, indicating the temperature inside the vial was reaching about 3000 kelvins. Chemical tests revealed he had produced graphene.

It turned out to be a type of graphene that is ideal for bulk uses. As the carbon atoms condense to form graphene, they don’t have time to stack in a regular pattern, as they do in graphite. The result is a material known as turbostatic graphene, with graphene layers jumbled at all angles atop one another. “That’s a good thing,” Duy says. When added to water or other solvents, turbostatic graphene remains suspended instead of clumping up, allowing each fleck of the material to interact with whatever composite it’s added to.

“This will make it a very good material for applications,” says Monica Craciun, a materials physicist at the University of Exeter. In 2018, she and her colleagues reported that adding graphene to concrete more than doubled its compressive strength. Tour’s team saw much the same result. When they added just 0.05% by weight of their flash-produced graphene to concrete, the compressive strength rose 25%; graphene added to polydimethylsiloxane, a common plastic, boosted its strength by 250%.

As digital control spreads across energy networks, research to counter ransomware-driven blackouts is increasingly important for grid resilience.

Those results could reignite efforts to use graphene in a wide range of composites. Researchers in Italy reported recently that adding graphene to asphalt dramatically reduces its tendency to fracture and more than doubles its life span. Last year, Iterchimica, an Italian company, began to test a 250-meter stretch of road in Milan paved with graphene-spiked asphalt. Tests elsewhere have shown that adding graphene to paint dramatically improves corrosion resistance.

These applications would require high-quality graphene by the ton. Fortunately, the starting point for flash graphene could hardly be cheaper or more abundant: Virtually any organic matter, including coffee grounds, food scraps, old tires, and plastic bottles, can be vaporized to make the material. “We’re turning garbage into graphene,” Duy says.

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Eastern U.S. Heatwave Electricity Demand surges to record peak load, straining the power grid, lifting wholesale prices, and prompting demand response, conservation measures, and load shedding to protect grid reliability during extreme temperatures.

Key Points

It is the record peak load from extreme heat, straining grids, lifting wholesale prices, and prompting demand response.

✅ Peak electricity use stresses regional power grid.

✅ Prices surge; conservation and demand response urged.

✅ Utilities monitor load, avoid outages via load shedding.

As temperatures soar to unprecedented highs across the Eastern United States, a blistering heatwave has triggered record-breaking electricity demand. This article delves into the causes behind the surge in energy consumption, its impact on the power grid, and measures taken to manage the strain during this extraordinary weather event.

Intensifying Heatwave Conditions

The Eastern U.S. is currently experiencing one of its hottest summers on record, with temperatures climbing well above seasonal norms. This prolonged heatwave has prompted millions of residents to rely heavily on air conditioning and cooling systems to escape the sweltering heat, with electricity struggles worsening in several communities, driving up electricity usage to peak levels.

Strain on Power Grid Infrastructure

The surge in electricity demand during the heatwave has placed significant strain on the region's power grid infrastructure, with supply-chain constraints complicating maintenance and equipment availability during peak periods.

Record-breaking Energy Consumption

The combination of high temperatures and increased cooling demands has led to record-breaking energy consumption levels across the Eastern U.S. States like New York, Pennsylvania, and Maryland have reported peak electricity demand exceeding previous summer highs, with blackout risks drawing heightened attention from operators, highlighting the extraordinary nature of this heatwave event.

Impact on Energy Costs and Supply

The spike in electricity demand during the heatwave has also affected energy costs and supply dynamics. Wholesale electricity prices have surged in response to heightened demand, contributing to sky-high energy bills for many households, reflecting the market's response to supply constraints and increased operational costs for power generators and distributors.

Management Strategies and Response

Utility companies and grid operators have implemented various strategies to manage electricity demand and maintain grid reliability during the heatwave. These include voluntary conservation requests, load-shedding measures, and real-time monitoring of grid conditions to prevent power outages while avoiding potential blackouts or disruptions.

Community Outreach and Public Awareness

Amidst the heatwave, community outreach efforts play a crucial role in raising public awareness about energy conservation and safety measures. Residents are encouraged to conserve energy during peak hours, adjust thermostat settings, and utilize energy-efficient appliances to alleviate strain on the power grid and reduce overall energy costs.

Climate Change and Resilience

The intensity and frequency of heatwaves are exacerbated by climate change, underscoring the importance of building resilience in energy infrastructure and adopting sustainable practices. Investing in renewable energy sources, improving energy efficiency and demand response programs that can reduce peak demand, and implementing climate adaptation strategies are essential steps towards mitigating the impacts of extreme weather events like heatwaves.

Looking Ahead

As the Eastern U.S. navigates through this heatwave, stakeholders are focused on implementing lessons learned from California's grid response to enhance preparedness and resilience for future climate-related challenges. Collaborative efforts between government agencies, utility providers, and communities will be crucial in developing comprehensive strategies to manage energy demand, promote sustainability, and safeguard public health and well-being during extreme weather events.

Conclusion

The current heatwave in the Eastern United States has underscored the critical importance of reliable and resilient energy infrastructure in meeting the challenges posed by extreme weather conditions. By prioritizing energy efficiency, adopting sustainable energy practices, and fostering community resilience, stakeholders can work together to mitigate the impacts of heatwaves and ensure a sustainable energy future for generations to come.

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Frisco 100% Renewable Electricity Goal outlines decarbonization via Xcel Energy, wind, solar, and battery storage, enabling beneficial electrification and a smarter grid for 100% municipal power by 2025 and community-wide clean electricity by 2035.

Key Points

Frisco targets 100% renewable electricity: municipal by 2025, community by 2035, via Xcel decarbonization.

✅ Municipal operations to reach 100% renewable electricity by 2025

✅ Community-wide electricity to be 100% carbon-free by 2035

✅ Partnerships: Xcel Energy, wind, solar, storage, grid markets

Frisco has now set a goal of 100-per-cent renewable energy, joining communities on the road to 100% renewables across the country. But unlike some other resolutions adopted in the last decade, this one isn't purely aspirational. It's swimming with a strong current.

With the resolution adopted last week by the town council, Frisco joins 10 other Colorado towns and cities, plus Pueblo and Summit counties, a trend reflected in tracking progress on clean energy targets reports nationwide, in adopting 100-per-cent goals.

The goal is to get the municipality's electricity to 100-per-cent by 2025 and the community altogether by 2035, a timeline aligned with scenarios showing zero-emissions electricity by 2035 is possible in North America.

Decarbonizing electricity will be far easier than transportation, and transportation far easier than buildings. Many see carbon-free electricity as being crucial to both, a concept called "beneficial electrification," and point to ways to meet decarbonization goals that leverage electrified end uses.

Electricity for Frisco comes from Xcel Energy, an investor-owned utility that is making giant steps toward decarbonizing its power supply.

Xcel first announced plans to close its work-horse power plants early to take advantage of now-cheap wind and solar resources plus what will be the largest battery storage project east of the Rocky Mountains. All this will be accomplished by 2026 and will put Xcel at 55 per cent renewable generation in Colorado.

In December, a week after Frisco launched the process that produced the resolution, Xcel announced further steps, an 80 percent reduction in carbon dioxide emissions by 2030 as compared to 2050 levels. By 2050, the company vows to be 100 per cent "carbon-free" energy by 2050.

Frisco's non-binding goals were triggered by Fran Long, who is retired and living in Frisco. For eight years, though, he worked for Xcel in helping shape its response to the declining prices of renewables. In his retirement, he has also helped put together the aspirational goal adopted by Breckenridge for 100-per-cent renewables.

A task force that Long led identified a three-pronged approach. First, the city government must lead by example. The resolution calls for the town to spend $25,000 to $50,000 annually during the next several years to improve energy efficiency in its municipal facilities. Then, through an Xcel program called Renewable Connect, it can pay an added cost to allow it to say it uses 100-per-cent electricity from renewable sources.

Beyond that, Frisco wants to work with high-end businesses to encourage buying output from solar gardens or other devices that will allow them to proclaim 100-per-cent renewable energy. The task force also recommends a marketing program directed to homes and smaller businesses.

Goals of 100-per-cent renewable electricity are problematic, given why the grid isn't 100% renewable today for technical and economic reasons. Aspen Electric, which provides electricity for about two-thirds of the town, by 2015 had secured enough wind and hydro, mostly from distant locations, to allow it to proclaim 100 per cent renewables.

In fact, some of those electrons in Aspen almost certainly originate in coal or gas plants. That doesn't make Aspen's claim wrong. But the fact remains that nobody has figured out how, at least at affordable cost, to deliver 100-per-cent clean energy on a broad basis.

Xcel Energy, which supplies more than 60 per cent of electricity in Colorado, one of six states in which it operates, has a taller challenge. But it is a very different utility than it was in 2004, when it spent heavily in advertising to oppose a mandate that it would have to achieve 10 per cent of its electricity from renewable sources by 2020.

Once it lost the election, though, Xcel set out to comply. Integrating renewables proved far more easily than was feared. It has more than doubled the original mandate for 2020. Wind delivers 82 per cent of that generation, with another 18 per cent coming from community, rooftop, and utility-scale solar.

The company has become steadily more proficient at juggling different intermittent power supplies while ensuring lights and computers remain on. This is partly the result of practice but also of relatively minor technological wrinkles, such as improved weather forecasting, according to an Energy News Network story published in March.

For example, a Boulder company, Global Weather corporation, projects wind—and hence electrical production—from turbines for 10 days ahead. It updates its forecasts every 15 minutes.

Forecasts have become so good, said John T. Welch, director of power operations for Xcel in Colorado, that the utility uses 95 per cent to 98 per cent of the electricity generated by turbines. This has allowed the company to use its coal and natural gas plants less.M

Moreover, prices of wind and then solar declined slowly at first and then dramatically.

Xcel is now comfortable that existing technology will allow it to push from 55 per cent renewables in 2026 to an 80 per cent carbon reduction goal by 2030.

But when announcing their goal of emissions-free energy by mid-century in December, the company's Minneapolis-based chief executive, Ben Fowke, and Alice Jackson, the chief executive of the company's Colorado subsidiary, freely admitted they had no idea how they will achieve it. "I have a lot of confidence they will be developed," Fowke said of new technologies.

Everything is on the table, they said, including nuclear. But also including fossil fuels, if the carbon dioxide can be sequestered. So far, such technology has proven prohibitively expensive despite billions of dollars in federal support for research and deployment. They suggested it might involve new technology.

Xcel's Welch told Energy News Network that he believes solar must play a larger role, and he believes solar forecasting must improve.

Storage technology must also improve as batteries are transforming solar economics across markets. Batteries, such as produced by Tesla at its Gigafactory near Reno, can store electricity for hours, maybe even a few days. But batteries that can store large amounts of electricity for months will be needed in Colorado. Wind is plentiful in spring but not so much in summer, when air conditioners crank up.

Increased sharing of cheap renewable generation among utilities will also allow deeper penetration of carbon-free energy, a dynamic consistent with studies finding wind and solar could meet 80% of demand with improved transmission. Western US states and Canadian provinces are all on one grid, but the different parts are Balkanized. In other words, California is largely its own energy balancing authority, ensuring electricity supplies match electricity demands. Ditto for Colorado. The Pacific Northwest has its own balancing authority.

If they were all orchestrated as one in an expanded energy market across the West, however, electricity supplies and demands could more easily be matched. California's surplus of solar on summer afternoons, for example, might be moved to Colorado.

Colorado legislators in early May adopted a bill that requires the state's Public Utilities Commission to begin study by late this year of an energy imbalance market or regional transmission organization.

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