More Efficient Wind Turbine Blade Designed

By Science Daily


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A new wind turbine blade design that researchers at Sandia National Laboratories developed in partnership with Knight & Carver (K&C) of San Diego promises to be more efficient than current designs. It should significantly reduce the cost-of-energy (COE) of wind turbines at low-wind-speed sites.

Named "STAR" for Sweep Twist Adaptive Rotor, the blade is the first of its kind produced at a utility-grade size. Its most distinctive characteristic is a gently curved tip, termed "sweep," which unlike the vast majority of blades in current use, is specially designed for low-wind-speed regions like the Midwest. The sites targeted by this effort have annual average wind speeds of 5.8 meters per second, measured at 10-meter height. Such sites are abundant in the U.S. and would increase by 20-fold the available land area that can be economically developed for wind energy.

Sized at 27.1 meters - almost three meters longer than the baseline it will replace - the blade improves energy capture at lower wind speeds. Instead of the traditional linear shape, the blade features a curvature toward the trailing edge, which allows the blade to respond to turbulent gusts in a manner that lowers fatigue loads on the blade. It is made of fiberglass and epoxy resin.

"This design allows the blade to twist more than traditional designs, thus relieving some of the effects of gusty turbulent wind on blade life," says Tom Ashwill, who leads Sandia's blade research efforts. "This then allows us to grow the blade length for the same rotor, providing for increased energy capture of 5-10 percent and yet retaining the same expected fatigue life."

Sandia is a National Nuclear Security Administration (NNSA) laboratory.

The K&C contract is part of the Low Wind Speed Technology (LWST) project that targets wind sites that are not the strongest but plentiful. In late 2005 the Department of Energy (DOE) and Sandia awarded Knight & Carver the $2 million contract that includes $800,000 in K&C cost share. Because of budget reallocations, this project was the only one of several LWST projects to receive 2007 funding.

Sandia's role in the project has been in directing design and test planning. The K&C team provided the detailed design and blade fabrication.

The first STAR blade was tested in January at Knight & Carver's fabrication facility in San Diego to determine its bending and twist behavior due to static loads. Natural frequencies were also measured. This data will be compared to design simulations to determine how well the design concept performs. Four additional blades will be fabricated in the first quarter of 2007 - three of which will be flight-tested on a turbine in Iowa.

"The DOE interest and funding are a big step for us," Ashwill says. "We've been pushing for the incorporation of innovative concepts into utility-scale blades for some time now as a way of reaching program goals of lowered cost of energy."

He adds that the continued increase in the average size of utility-grade wind turbines may come to an end before all efficiencies are wrung out unless blade weight growth (which is nonlinear) can be reined in. The challenge is to develop new concepts that reduce the rate of weight growth, such as the swept STAR blade.

Other weight-reducing concepts such as carbon spar caps, off-axis carbon fibers that facilitate bend-twist coupling, and new "structural" airfoils have been incorporated at a smaller scale in 9-meter-long prototype blade being flight-tested at Sandia's test site in Bushland, Texas, at the U.S. Department of Agriculture ARS (Agriculture Research Station) facility.

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Drought, lack of rain means BC Hydro must adapt power generation

BC Hydro drought operations address climate change impacts with hydropower scheduling, reservoir management, water conservation, inflow forecasting, and fish habitat protection across the Lower Mainland and Vancouver Island while maintaining electricity generation from storage facilities.

 

Key Points

BC Hydro drought operations conserve water, protect fish, and sustain hydropower during extended heat and low inflows.

✅ Proactive reservoir releases protect downstream salmon spawning.

✅ Reduced flows at Puntledge, Coquitlam, and Ruskin/Stave facilities.

✅ System relies on northern storage to maintain electricity supply.

 

BC Hydro is adjusting its operating plans around power generation as extended heat and little forecast rain continue to impact the province, a report says.

“Unpredictable weather patterns related to climate change are expected to continue in the years ahead and BC Hydro is constantly adapting to these evolving conditions, especially after events such as record demand in 2021 that tested the grid,” said the report, titled “Casting drought: How climate change is contributing to uncertain weather and how BC Hydro’s generation system is adapting.”

The study said there is no concern with BC Hydro being able to continue to deliver power through the drought because there is enough water at its larger facilities, even as issues like crypto mining electricity use draw scrutiny from observers.

Still, it said, with no meaningful precipitation in the forecast, its smaller facilities in the Lower Mainland and on Vancouver Island will continue to see record low or near record low inflows for this time of the year.

“In the Lower Mainland, inflows since the beginning of September are ranked in the bottom three compared to historical records,” the report said.

The report said the hydroelectric system is directly impacted by variations in weather and the record-setting, unseasonably dry and warm weather this fall highlights the impacts of climate change, while demand patterns can be counterintuitive, as electricity use even increased during Earth Hour 2018 in some areas, hinting at challenges to come.

It noted symptoms of climate change include increased frequency of extreme events like drought and intense storms, and rapid glacial melt.

“With the extremely hot and dry conditions, BC Hydro has been taking proactive steps at many of our South Coast facilities for months to conserve water to protect the downstream fish habit,” spokesperson Mora Scott said. “We began holding back water in July and August at some facilities anticipating the dry conditions to help ensure we would have water storage for the later summer and early fall salmon spawning.”

Scott said BC Hydro’s reservoirs play an important role in managing these difficult conditions by using storage and planning releases to provide protection to downstream river flows. The reservoirs are, in effect, a battery waiting to be used for power.

While the dry conditions have had an impact on BC Hydro’s watersheds, several unregulated natural river systems — not related to BC Hydro — have fared worse, with rivers drying up and thousands of fish killed, the report said.

BC Hydro is currently seeing the most significant impacts on operations at Puntledge and Campbell River on Vancouver Island as well as Coquitlam and Ruskin/Stave in the Lower Mainland.

To help manage water levels on Vancouver Island, BC Hydro reduced Puntledge River flows by one-third last week and on the Lower Mainland reduced flows at Coquitlam by one-third and Ruskin/Stave by one quarter.

However, the utility company said, there are no concerns about continued power delivery.

“British Columbians benefit from BC Hydro’s integrated, provincial electricity system, which helps send power across the province, including to Vancouver Island, and programs like the winter payment plan support customers during colder months,” staff said.

Most of the electricity generated and used in B.C. is produced by larger facilities in the north and southeast of the province — and while water levels in those areas are below normal levels, there is enough water to meet the province’s power needs, even as additions like Site C's electricity remain a subject of debate among observers.

The Glacier Media investigation found a quarter of BC Hydro's power comes from the Mica, Revelstoke and Hugh Keenleyside dams on the Columbia River. Some 29% comes from dams in the Peace region, including the under-construction Site C project that has faced cost overruns. At certain points of the year, those reservoirs are reliant on glacier water.

Still, BC Hydro remains optimistic.

Forecasts are currently showing little rain in the near-term; however, historically, precipitation and inflows show up by the end of October. If that does not happen, BC Hydro said it would continue to closely track weather and inflow forecasts to adapt its operations to protect fish, while regional cooperation such as bridging with Alberta remains part of broader policy discussions.

Among things BC Hydro said it is doing to adapt are:

Continuously working to improve its weather and inflow forecasting;
Expanding its hydroclimate monitoring technology, including custom-made solutions that have been designed in-house, as well as upgrading snow survey stations to automated, real-time snow and climate stations, and;
Investing in capital projects — like spillway gate replacements — that will increase resiliency of the system to climate change.

 

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How waves could power a clean energy future

Wave Energy Converters can deliver marine power to the grid, with DOE-backed PacWave enabling offshore testing, robust designs, and renewable electricity from oscillating waves to decarbonize coastal communities and replace diesel in remote regions.

 

Key Points

Wave energy converters are devices that transform waves' oscillatory motion into electricity for the grid or loads.

✅ DOE's PacWave enables full-scale, grid-connected offshore testing.

✅ Multiple designs convert oscillating motion into torque and power.

✅ Ideal for islands, microgrids, and replacing diesel generation.

 

Waves off the coast of the U.S. could generate 2.64 trillion kilowatt hours of electricity per year — that’s about 64% of last year’s total utility-scale electricity generation in the U.S. We won’t need that much, but one day experts do hope that wave energy will comprise about 10-20% of our electricity mix, alongside other marine energy technologies under development today.

“Wave power is really the last missing piece to help us to transition to 100% renewables, ” said Marcus Lehmann, co-founder and CEO of CalWave Power Technologies, one of a number of promising startups focused on building wave energy converters.

But while scientists have long understood the power of waves, it’s proven difficult to build machines that can harness that energy, due to the violent movement and corrosive nature of the ocean, combined with the complex motion of waves themselves, even as a recent wave and tidal market analysis highlights steady advances.

″Winds and currents, they go in one direction. It’s very easy to spin a turbine or a windmill when you’ve got linear movement. The waves really aren’t linear. They’re oscillating. And so we have to be able to turn this oscillatory energy into some sort of catchable form,” said Burke Hales, professor of cceanography at Oregon State University and chief scientist at PacWave, a Department of Energy-funded wave energy test site off the Oregon Coast. Currently under construction, PacWave is set to become the nation’s first full-scale, grid-connected test facility for these technologies, a milestone that parallels U.K. wind power lessons on scaling new industries, when it comes online in the next few years.

“PacWave really represents for us an opportunity to address one of the most critical barriers to enabling wave energy, and that’s getting devices into the open ocean,” said Jennifer Garson, Director of the Water Power Technologies Office at the U.S. Department of Energy.

At the beginning of the year, the DOE announced $25 million in funding for eight wave energy projects to test their technology at PacWave, as offshore wind forecasts underscore the growing investor interest in ocean-based energy. We spoke with a number of these companies, which all have different approaches to turning the oscillatory motion of the waves into electrical power.

Different approaches
Of the eight projects, Bay Area-based CalWave received the largest amount, $7.5 million. 

″The device we’re testing at PacWave will be a larger version of this,” said Lehmann. The x800, our megawatt-class system, produces enough power to power about 3,000 households.”

CalWave’s device operates completely below the surface of the water, and as waves rise and fall, surge forward and backward, and the water moves in a circular motion, the device moves too. Dampers inside the device slow down that motion and convert it into torque, which drives a generator to produce electricity, a principle mirrored in some wind energy kite systems as they harvest aerodynamic forces.

“And so the waves move the system up and down. And every time it moves down, we can generate power, and then the waves bring it back up. And so that oscillating motion, we can turn into electricity just like a wind turbine,” said Lehmann.

Another approach is being piloted by Seattle-based Oscilla Power, which was awarded $1.8 million from the DOE, and is getting ready to deploy its wave energy converter off the coast of Hawaii, at the U.S. Navy Wave Energy Test site.

Oscilla Power’s device is composed of two parts. One part floats on the surface and moves with the waves in all directions — up and down, side to side and rotationally. This float is connected to a large, ring-shaped structure which hangs below the surface, and is designed to stay relatively steady, much like how underwater kites leverage a stable reference to generate power. The difference in motion between the float and the ring generates force on the connecting lines, which is used to rotate a gearbox to drive a generator.

″The system that we’re deploying in Hawaii is what we call the Triton-C. This is a community-scale system,” said Balky Nair, CEO of Oscilla Power. “It’s about a third of the size of our flagship product. It’s designed to be 100 kilowatt rated, and it’s designed for islands and small communities.”

Nair is excited by wave energy’s potential to generate electricity in remote regions, which currently rely on expensive and polluting diesel imports to meet their energy needs when other renewables aren’t available, and similar tidal energy for remote communities efforts in Canada point to viable models. Before wave energy is adopted at-scale, many believe we’ll see wave energy replacing diesel generators in off-the-grid communities.

A third company, C-Power, based in Charlottesville, Virginia, was awarded more than $4 million to test its grid-scale wave energy converter at PacWave. But first, the company wants to commercialize its smaller scale system, the SeaRAY, which is designed for lower-power applications. 

″Think about sensors in the ocean, research, metocean data gathering, maybe it’s monitoring or inspection,” said C-Power CEO Reenst Lesemann on the initial applications of his device.

The SeaRAY consists of two floats and a central body, the nacelle, which contains the drivetrain. As waves pass by, the floats bob up and down, rotating about the nacelle and turning their own respective gearboxes which power the electric generators.

Eventually, C-Power plans to scale up its SeaRAY so that it’s capable of satellite communications and deep water deployments, before building a larger system, called the StingRAY, for terrestrial electricity generation.

Meanwhile, one Swedish company, Eco Wave Power, is taking another approach completely, eschewing offshore technologies in favor of simpler wave power devices that can be installed on breakwaters, piers, and jetties.

“All the expensive conversion machinery, instead of being inside the floaters like in the competing technologies, is on land just like a regular power station. So basically this enables a very low installation, operation, and maintenance cost,” explained CEO Inna Braverman.

 

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Scottish North Sea wind farm to resume construction after Covid-19 stoppage

NnG Offshore Wind Farm restarts construction off Scotland, backed by EDF Renewables and ESB, CfD 2015, 54 turbines, powering 375,000 homes, 500 jobs, delivering GBP 540 million, with Covid-19 safety measures and staggered workforce.

 

Key Points

A 54-turbine Scottish offshore project by EDF Renewables and ESB, resuming to power 375,000 homes and support 500 jobs.

✅ Awarded a CfD in 2015; 54 turbines off Scotland's east coast.

✅ Projected to power 375,000 homes and deliver GBP 540 million locally.

✅ Staggered workforce return with Covid-19 control measures and oversight.

 

Neart Na Gaoithe (NnG) Offshore Wind Farm, owned by  EDF Renewables and Irish firm ESB, stopped construction in March, even as the world's most powerful tidal turbine showcases progress in marine energy.

Project boss Matthias Haag announced last night the 54-turbine wind farm would restart construction this week, as the largest UK offshore wind farm begins supplying power, underscoring sector momentum.

Located off Scotland’s east coast, where wind farms already power millions of homes, it was awarded a Contract for Difference (CfD) in 2015 and will look to generate enough energy to power 375,000 homes.

It is expected to create around 500 jobs, and supply chain growth like GE's new offshore blade factory jobs shows wider industry momentum, while also delivering £540 million to the local economy.

Mr Haag, NnG project director, said the wind farm build would resume with a small, staggered workforce return in line social distancing rules, and with broader energy sector conditions, including Hinkley Point C setbacks that challenge the UK's blueprint.

He added: “Initially, we will only have a few people on site to put in place control measures so the rest of the team can start work safely later that week.

“Once that’s happened we will have a reduced workforce on site, including essential supervisory staff.

“The arrangements we have put in place will be under regular review as we continue to closely monitor Covid-19 and follow the Scottish Government’s guidance.”

NnG wind farm, a 54-turbine projects, was due to begin full offshore construction in June 2020 before the Covid-19 outbreak, at a time when a Scottish tidal project had just demonstrated it could power thousands of homes.

EDF Renewables sold half of the NnG project to Irish firm ESB in November last year, and parent company EDF recently saw the Hinkley C reactor roof lifted into place, highlighting progress alongside renewables.

The first initial payment was understood to be around £50 million.

 

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Analysis: Out in the cold: how Japan's electricity grid came close to blackouts

Japan Electricity Crunch exposes vulnerabilities in a liberalised power market as LNG shortages, JEPX price spikes, snow-hit solar, and weak hedging strain energy security and retail providers amid cold snap demand and limited reserve capacity.

 

Key Points

A winter demand shock and LNG shortfalls sent JEPX to records, exposing gaps in hedging, data, and energy security.

✅ JEPX wholesale prices spiked to an all-time high

✅ LNG inventories and procurement proved insufficient

✅ Snow disabled solar; new entrants lacked hedging

 

Japan's worst electricity crunch since the aftermath of the Fukushima crisis has exposed vulnerabilities in the country's recently liberalised power market, although some of the problems appear self-inflicted.

Power prices in Japan hit record highs last month, mirroring UK peak power prices during tight conditions, as a cold snap across northeast Asia prompted a scramble for supplies of liquefied natural gas (LNG), a major fuel for the country's power plants. Power companies urged customers to ration electricity to prevent blackouts, although no outages occurred.

The crisis highlighted how many providers were unprepared for such high demand. Experts say LNG stocks were not topped up ahead of winter and snow disabled solar power farms, while China's power woes strained solar supply chains.

The hundreds of small power companies that sprang up after the market was opened in 2016 have struggled the most, saying the government does not disclose the market data they need to operate. The companies do not have their own generators, instead buying electricity on the wholesale market.

Prices on the Japan Electric Power Exchange (JEPX) hit a record high of 251 yen ($2.39) per kilowatt hour in January, equating to $2,390 per megawatt hour of electricity, above record European price surges seen recently and the highest on record anywhere in the world. One megawatt hour is roughly what an average home in the U.S. would consume over 35 days.

But the vast majority of the new, smaller companies are locked into low, fixed rates they set to lure customers from bigger players, crushing them financially during a price spike like the one in January.

More than 50 small power providers wrote on Jan. 18 to Japan's industry minister, Hiroshi Kajiyama, who oversees the power sector, asking for more accessible data on supply and demand, reserve capacity and fuel inventories.

"By organising and disclosing this information, retail electricity providers will be able to bid at more appropriate prices," said the companies, led by Looop Co.

They also called on Kajiyama to require transmission and distribution companies to pass on some of the unexpected profits from price spikes to smaller operators.

The industry ministry said it had started releasing more timely market data, and is reviewing the cause of the crunch and considering changes, echoing calls by Fatih Birol to keep electricity options open amid uncertainty.

Japan reworked its power markets after the Fukushima nuclear disaster in 2011, liberalizing the sector in 2016 while pushing for more renewables.

But Japan is still heavily reliant on LNG and coal, and only four of 33 nuclear reactors are operating. The power crisis has led to growing calls to restart more reactors.

Kazuno Power, a small retail provider controlled by a municipality of the same name in northern Japan, where abundant renewable energy is locally produced, buys electricity from hydropower stations and JEPX.

During the crunch, the company had to pay nearly 10 times the usual price, Kazuno Power president Takao Takeda said in an interview. Like most other new providers, it could not pass on the costs, lost money, and folded. The local utility has taken over its customers.

"There is a contradiction in the current system," Takeda said. "We are encouraged to locally produce power for local consumption as well as use more renewable energy, but prices for these power supplies are linked to wholesale prices, which depend on the overall power supply."

The big utilities, which receive most of their LNG on long-term contracts, blamed the power shortfall on a tight spot market and glitches at generation units.

"We were not able to buy as much supply as we wanted from the spot market because of higher demand from South Korea and China, where power cuts have tightened supply," Kazuhiro Ikebe, the head of the country's electricity federation, said recently.

Ikebe is also president of Kyushu Electric Power, which supplies the southern island of Kyushu.

Utilities took extreme measures - from burning polluting fuel oil in coal plants to scavenging the dregs from empty LNG tankers - to keep the grid from breaking down.

"There is too much dependence on JEPX for procurement," said Bob Takai, the local head of European Energy Exchange, where electricity pricing reforms are being discussed, and which started offering Japan power futures last year. He added that new entrants were not hedging against sharp price moves.

Three people, who requested anonymity because of the sensitivity of the matter, were more blunt. One called the utilities arrogant in assuming they could find LNG cargoes in a pinch. Prices were already rising as China snapped up supplies, the sources noted.

"You had volatility caused by people saying 'Oh, well, demand is going to be weak because of coronavirus impacts' and then saying 'we can rely more on solar than in the past,' but solar got snowed out," said a senior executive from one generator. "We have a problem of who is charge of energy security in Japan."

Inventories of LNG, generally about two weeks worth of supplies, were also not topped up enough to prepare for winter, a market analyst said.

The fallout from the crunch has become more apparent in recent days, with new power companies like Rakuten Inc suspending new sales and Tokyo Gas, along with traditional electricity utilities, issuing profit downgrades or withdrawing their forecasts.

Although prices have fallen sharply as temperatures warmed up slightly and more generation units have come back online, the power generator executive said, "we are not out of the woods yet."
 

 

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Texans to vote on funding to modernize electricity generation

Texas Proposition 7 Energy Fund will finance ERCOT grid reliability via loans and grants for new on-demand natural gas plants, maintenance, and modernization, administered by the Public Utility Commission of Texas after Winter Storm Uri.

 

Key Points

State-managed fund providing loans and grants to expand and upgrade ERCOT power generation for grid reliability.

✅ $7.2B incentives for new dispatchable plants in ERCOT

✅ Administered by Public Utility Commission of Texas

✅ Aims to prevent outages like Winter Storm Uri

 

Texans are set to vote on Tuesday on a constitutional amendment to determine whether the state will create a special fund for financing the "construction, maintenance, and modernization of its electric generating facilities."

The energy fund would be administered and used only by the Public Utility Commission of Texas to provide loans and grants to maintain and upgrade electric generating facilities and improve electricity reliability across the state.

The biggest chunk of the fund, $7.2 billion, would go into loans and incentives to build new power-generating facilities in the ERCOT (Electric Reliability Council of Texas) region, where ERCOT has issued an RFP for winter capacity to address seasonal concerns.

The proposal, titled Proposition 7, is one of several electricity market reforms under consideration by lawmakers and regulators in Texas to avoid another energy crisis like the one caused by a deadly winter storm in February 2021.

That storm, known as Winter Storm Uri, left millions without power, water and heat for days as ERCOT struggled to prevent a grid collapse after the shutdown of an unusually large amount of generation, and bailout proposals soon surfaced in the Legislature as the market reeled.

Pablo Vegas, president and CEO of ERCOT, emphasized the grid has become more “volatile” given the current resources, as the Texas power grid faces recurring challenges.

“The complexities of managing a growing demand, and a very dynamic load environment with those types of resources becomes more and more challenging,” Vegas said Tuesday during a meeting of the ERCOT board of directors.

Vegas said one solution to overcome the challenge is investing in power production that is available on demand, like power plants fueled by natural gas. Those plants can help during times when the need for electricity strains the supply.

“With the passing of Proposition 7 on the ballot this November, we’ll see those incentives combined to incentivize a more balanced development strategy going forward,” Vegas told board members.

If Proposition 7 is passed by voters, it would enact S.B. 2627, which establishes an advisory committee to oversee the fund and the various projects it could be used for, amid severe-heat blackout risks that affect the broader U.S. $5 billion would be transferred from the General Revenue Fund to the Texas Energy Fund if Proposition 7 passes.

Opposition for Proposition 7 comes from the Lone Star chapter of the Sierra Club, an environmental organization based in Austin and which has issued a statement on Gov. Abbott's demands regarding grid policy. Cyrus Reed, conservation director of the Lone Star chapter, said the Texas energy fund is slated to benefit private utilities to build gas plants using taxpayer’s money.

 

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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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