TVA sees a future in clean coal generation

By Knoxville News Sentinel


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Well over half of the electricity used by homes and businesses in the Tennessee Valley region comes from burning coal. This roughly mirrors the national use of coal, a plentiful domestic energy source that has fueled our economy and our way of life for many years.

Meeting the environmental challenges of a fuel that generates such a large portion of our electricity is a priority for TVA. Like all electric utilities, whether public or private, we are responsible for meeting electricity demand as reliably and economically as possible in the public interest.

The national campaign to dismiss the future of "clean coal" technology fails to credit substantial progress that has been made in reducing fossil fuel emissions and the continuing research to further minimize the environmental impacts of an important national energy source.

Data compiled by the U.S. Environmental Protection Agency show that air quality has improved steadily during the past three decades since national standards were established by the Clean Air Act in 1970. During this time, TVA has invested more than $5 billion in emissions control equipment at our plants across the Valley and will install another $400 million worth of controls by the end of 2010. Complying with interstate emission rules now under discussion could require an additional $3 billion investment in coming years.

These costs become the price we all pay for electricity.

Installing emission controls and switching to cleaner types of coal have reduced regulated emissions by more than 80 percent since the late 1970s. Reductions approaching 90 percent are expected with the installation of additional equipment.

Along with emissions, the other major environmental challenge posed for most utilities that use coal is managing waste byproducts-primarily ash and gypsum. The issue was brought to the forefront last December by the coal ash spill at TVA's Kingston Fossil Plant.

To ensure the safety of our coal waste storage facilities, TVA is planning to close all wet storage impoundments and establish dry storage for all our coal plants. TVA is taking these steps to achieve the safest coal waste management program in the industry.

The investments in emission controls and coal byproduct waste management are necessary to maintain a reliable power supply while TVA pursues a strategy to reduce our carbon footprint.

Currently, more than 30 percent of TVA's generation comes from zero or near-zero carbon-emitting fuels, such as nuclear and hydropower, along with a small but growing amount of renewable energy from wind, solar and methane gas.

Negotiations are under way with renewable energy suppliers to add up to 2,000 megawatts or more of renewable energy, mostly wind power, as it becomes available during the next two to three years.

The addition of more renewable energy, the completion of a second nuclear unit at Watts Bar Nuclear Plant in 2013 and the possible addition of future nuclear units at the Bellefonte site in North Alabama support TVA's move toward having at least 50 percent of its power supply provided by zero or near-zero carbon-emitting sources by 2020.

At the same time, we are working with state and federal officials to develop energy efficiency incentives that encourage consumers to be wiser and more frugal about energy use.

The collective progress toward developing a larger supply of cleaner energy will certainly benefit air quality and reduce the amount of coal byproducts that have to be managed. It is realistic and important for TVA to pursue a cleaner energy strategy for the future while responsibly managing the environmental challenges of a reliable energy source that we all depend upon today.

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Ontario Government Consults On Changes To Industrial Electricity Pricing And Programs

Ontario electricity pricing consultations will gather business input on OEB rate design, Industrial Conservation Initiative, dynamic pricing, global adjustment, and system costs through online feedback and sector-specific in-person sessions province-wide.

 

Key Points

Consultations gathering business input on rates, programs, and OEB policy to improve fairness and reduce system costs.

✅ Consults on ICI, GA, dynamic pricing structures

✅ Seeks views on OEB C&I rate design changes

✅ In-person sessions across key industrial sectors

 

The Ontario government has announced plans to hold consultations to seek input from businesses about industrial electricity pricing and programs. This will be done through Ontario's online consultations directory and though in-person sector-specific consultation sessions across the province. The in-person sessions will be held in all areas of Ontario, and will target "key industries," including automotive and the build-out of electric vehicle charging stations infrastructure, forestry, mining, agriculture, steel, manufacturing and chemicals.

On April 1, 2019, the Ontario government published a consultation notice for this process, confirming that it is looking for input on "electricity rate design, existing tax-based incentives, reducing system costs and regulatory and delivery costs," including related proposals such as the hydrogen rate reduction proposal under discussion. The consultation process includes a list of nine questions for respondents (and presumably participants in the in-person sessions) to address. These include questions about:

The benefits of the Industrial Conservation Initiative (described below), including how it could be changed to improve fairness and industrial competitiveness, and how it could complement programs like the Hydrogen Innovation Fund that support industrial innovation.

Dynamic pricing structures that allow for lower rates in return for responding to price signals versus a flat rate structure that potentially costs more, but is more stable and predictable, as Ontario's energy storage expansion accelerates.

Interest in an all-in commodity contract with an electricity retailer, even if it involves a risk premium.

Interested parties are invited to submit their comments before May 31, 2019.

The government's consultation announcement follows recent developments in the Ontario Energy Board's (OEB) review of electricity ratemaking for commercial and industrial customers, and intertie projects such as the Lake Erie Connector that could affect market dynamics.

In December 2018, the OEB published a paper from its Market Surveillance Panel (MSP) examining the Industrial Conservation Initiative (ICI), and potential alternative approaches. The ICI is a program that allows qualifying large industrial customers to base their global adjustment (GA) payments on their consumption during five peak demand hours in a year. Customers who find ways to reduce consumption at those times, perhaps through DERs and enabling energy storage options, will reduce their electricity costs. This shifts GA costs to other customers. The MSP found that the ICI does not fairly allocate costs to those who cause them and/or benefit from them, and recommends that a better approach should be developed.

In February 2019, the OEB released its Staff Report to the Board on Rate Design for Commercial and Industrial Electricity Customers, setting out recommendations for new rate designs for electricity commercial and industrial (C&I) rate classes as Ontario increasingly turns to battery storage to meet rising demand. As described in an earlier post, the Staff Report includes recommendations to: (i) establish a fixed distribution charge for commercial customers with demands under 10 kW; (ii) implement a demand charge (rather than the current volumetric charge) for C&I customers with demands between 10kW and 50kW; and (iii) introduce a "capacity reserve charge" for customers with load displacement generation to replace stand-by charges and provide for recognition of the benefits of this generation on the system. The OEB held a stakeholder information session in mid-March on this initiative, and interested parties are now filing submissions in response to the Staff Report.

Whether and how the OEB's processes will fit together with the government's consultation process remains to be seen.

 

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Electricity complaints filed by Texans reach three-year high, report says

Texas Electricity Complaints surged to a three-year high, highlighting Public Utility Commission data on billing disputes, meter problems, and service issues in the competitive retail electricity market and consumer protection process.

 

Key Points

Consumer filings to Texas PUC about billing, service, and meters, with 2018 reaching a three-year high.

✅ 5,371 complaints/inquiries in FY2018; 43.8% involved billing disputes.

✅ Service issues 15.8% and meters 12.6%; PUC publishes complaint stats.

✅ Advocates urge monitoring to keep deregulated retail market healthy.

 

The number of electricity service-related complaints and inquiries filed with the state’s Public Utility Commission reached a three-year high this past fiscal year, an advocacy group said Tuesday.

According to the Texas Coalition for Affordable Power, a nonprofit that advocates for low electricity prices, Texans filed 5,371 complaints or inquiries with the commission between September 2017 and August of this year. That’s up from the 4,175 complaints or inquiries filed during the same period in 2017 and the 4,835 filed in 2016. The complaints and inquiries included concerns with billing, meters and service.

“This stark uptick in complaints is disappointing — especially after several years of generally improving numbers,” Jay Doegey, the coalition's executive director, said in a written statement. “In percentage terms, the year-to-year rise in complaints is the greatest in a decade. Clearly, many Texans remain frustrated with aspects of their electric service.”

The utility commission did not immediately respond to a request for comment.

While complaints and inquiries increased in 2018, the number of complaints and inquiries has generally decreased since 2009, when Texans filed 15,956 with the commission. That could be because there have been lower residential electricity prices and because Texans have become more familiar with the state’s competitive retail electricity system over the last decade, the coalition's report said.

And complaints from 2018 are well below 2003 levels, when the number of complaints and inquiries soared to more than 17,000, a year after Texas deregulated most of its electricity market structure at the time.

But Jake Dyer, a policy analyst at the coalition, said his group is closely watching the uptick in complaints this year as the Texas power grid faces recurring strains.

“We are invested in making sure the competition works,” Dyer said. “When you see an uptick like this, you should watch very closely to make sure the market remains healthy and to make sure there is not something else going on.”

However, Dyer said that it is too early to know what that something else that is going on might be.

According to the report, concerns about billing made up most of the complaints and inquiries filed this year at 43.8 percent. That’s up from 42.5 percent in fiscal year 2017. Concerns about the provision of electrical service and about electrical meters also ranked high, constituting 15.8 percent and 12.6 percent of the complaints and inquiries, respectively.

The Public Utility Commission publishes customer complaint statistics on its website. The Texas Coalition for Affordable Power takes into account both complaints and inquiries filed with the commission for its report in order “to gauge general consumer sentiment and to maintain a uniform methodology across the study period.”

Texans can file an official complaint with the the commission's Customer Protection Division. Under the complaint process, the complaint is sent to the electric company, which has 21 days to respond.

Some providers outside the competitive market, such as electric cooperatives, drew praise for performance during the 2021 winter storm.

Following the 2021 winter storm, Texas lawmakers proposed an electricity market bailout to stabilize costs and reliability.

 

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German renewables deliver more electricity than coal and nuclear power for the first time

Germany renewable energy milestone 2019 saw wind, solar, hydropower, and biomass outproduce coal and nuclear, as low gas prices and high CO2 costs under the EU ETS reshaped the electricity mix, per Fraunhofer ISE.

 

Key Points

It marks H1 2019 when renewables supplied 47.3% of Germany's electricity, surpassing coal and nuclear.

✅ Driven by high CO2 prices and cheap natural gas

✅ Wind and solar output rose; coal generation declined sharply

✅ Flexible gas plants outcompeted inflexible coal units

 

In Lippendorf, Saxony, the energy supplier EnBW is temporarily taking part of a coal-fired power plant offline. Not because someone ordered it — it simply wasn't paying off. Gas prices are low, CO2 prices are high, and with many hours of sunshine and wind, renewable methods are producing a great deal of electricity as part of Germany's energy transition now reshaping operations. And in the first half of the year there was plenty of sun and wind.

The result was a six-month period in which renewable energy sources, a trend echoed by the EU wind and solar record across the bloc, produced more electricity than coal and nuclear power plants together. For the first time 47.3% of the electricity consumers used came from renewable sources, while 43.4% came from coal-fired and nuclear power plants.

In addition to solar and wind power, renewable sources also include hydropower and biomass. Gas supplied 9.3%, reflecting how renewables are crowding out gas across European power markets, while the remaining 0.4% came from other sources, such as oil, according to figures published by the Fraunhofer Institute for Solar Energy Systems in July.

Fabian Hein from the think tank Agora Energiewende stresses that the situation is only a snapshot in time, with grid expansion woes still shaping outcomes. For example, the first half of 2019 was particularly windy and wind power production rose by around 20% compared to the first half of 2018.

Electricity production from solar panels rose by 6%, natural gas by 10%, while the share of nuclear power in German electricity consumption has remained virtually unchanged despite a nuclear option debate in climate policy.

Coal, on the other hand, declined. Black coal energy production fell by 30% compared to the first half of 2018, lignite fell by 20%. Some coal-fired power plants were even taken off the grid, even as coal still provides about a third of Germany's electricity. It is difficult to say whether this was an effect of the current market situation or whether this is simply part of long-term planning, says Hein.

 

Activists storm German mine in anti-coal protest

It is clear, however, that an increased CO2 price has made the ongoing generation of electricity from coal more expensive. Gas-fired power plants also emit CO2, but less than coal-fired power plants. They are also more efficient and that's why gas-fired power plants are not so strongly affected by the CO2 price

The price is determined at a European level and covers power plants and energy intensive industries in Europe. Other areas, such as heating or transport are not covered by the CO2 price scheme. Since a reform of CO2 emissions trading in 2017, the price has risen sharply. Whereas in September 2016 it was just over €5 ($5.6), by the end of June 2019 it had climbed to over €26.

 

Ups and downs

Gas as a raw material is generally more expensive than coal. But coal-fired power plants are more expensive to build. This is why operators want to run them continuously. In times of high demand, and therefore high prices, gas-fired power plants are generally started up, as seen when European power demand hit records during recent heatwaves, since it is worth it at these times.

Gas-fired power plants can be flexibly ramped up and down. Coal-fired power plants take 11 hours or longer to get going. That's why they can't be switched on quickly for short periods when prices are high, like gas-fired power plants. In the first half of the year, however, coal-fired power plants were also ramped up and down more often because it was not always worthwhile to let the power plant run around the clock.

Because gas prices were particularly low in the first half of 2019, some gas-fired power plants were more profitable than coal-fired plants. On June 29, 2019, the gas price at the Dutch trading point TTF was around €10 per megawatt hour. A year earlier, it had been almost €20. This is partly due to the relatively mild winter, as there is still a lot of gas in reserve, confirmed a spokesman for the Federal Association of the Energy and Water Industries (BDEW). There are also several new export terminals for liquefied natural gas. Additionally, weaker growth and trade wars are slowing demand for gas. A lot of gas comes to Europe, where prices are still comparatively high, reported the Handelsblatt newspaper.

The increase in wind and solar power and the decline in nuclear power have also reduced CO2 emissions. In the first half of 2019, electricity generation emitted around 15% less CO2 than in the same period last year, reported BDEW. However, the association demands that the further expansion of renewable energies should not be hampered. The target of 65% renewable energy can only be achieved if the further expansion of renewable energy sources is accelerated.

 

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As New Zealand gets serious about climate change, can electricity replace fossil fuels in time?

New Zealand Energy Transition will electrify transport and industry with renewables, grid-scale solar, wind farms, geothermal, batteries, demand response, pumped hydro, and transmission upgrades to manage dry-year risk and winter peak loads.

 

Key Points

A shift to renewables and smart demand to decarbonise transport and industry while ensuring reliable, affordable power.

✅ Electrifies transport and industrial heat with renewables

✅ Uses demand response, batteries, and pumped hydro for resilience

✅ Targets 99%+ renewable supply, managing dry-year and peak loads

 

As fossil fuels are phased out over the coming decades, the Climate Change Commission (CCC) suggests electricity will take up much of the slack, aligning with the vision of a sustainable electric planet powering our vehicle fleet and replacing coal and gas in industrial processes.

But can the electricity system really provide for this increased load where and when it is needed? The answer is “yes”, with some caveats.

Our research examines climate change impacts on the New Zealand energy system. It shows we’ll need to pay close attention to demand as well as supply. And we’ll have to factor in the impacts of climate change when we plan for growth in the energy sector.

 

Demand for electricity to grow
While electricity use has not increased in NZ in the past decade, many agencies project steeply rising demand in coming years. This is partly due to both increasing population and gross domestic product, but mostly due to the anticipated electrification of transport and industry, which could result in a doubling of demand by mid-century.

It’s hard to get a sense of the scale of the new generation required, but if wind was the sole technology employed to meet demand by 2050, between 10 and 60 new wind farms would be needed nationwide.

Of course, we won’t only build wind farms, as renewables are coming on strong and grid-scale solar, rooftop solar, new geothermal, some new small hydro plant and possibly tidal and wave power will all have a part to play.

 

Managing the demand
As well as providing more electricity supply, demand management and batteries will also be important. Our modelling shows peak demand (which usually occurs when everyone turns on their heaters and ovens at 6pm in winter) could be up to 40% higher by 2050 than it is now.

But meeting this daily period of high demand could see expensive plant sitting idle for much of the time (with the last 25% of generation capacity only used about 10% of the time).

This is particularly a problem in a renewable electricity system when the hydro lakes are dry, as hydro is one of the few renewable electricity sources that can be stored during the day (as water behind the dam) and used over the evening peak (by generating with that stored water).

Demand response will therefore be needed. For example, this might involve an industrial plant turning off when there is too much load on the electricity grid.

 

But by 2050, a significant number of households will also need smart appliances and meters that automatically use cheaper electricity at non-peak times. For example, washing machines and electric car chargers could run automatically at 2am, rather than 6pm when demand is high.

Our modelling shows a well set up demand response system could mitigate dry-year risk (when hydro lakes are low on water) in coming decades, where currently gas and coal generation is often used.

Instead of (or as well as) having demand response and battery systems to combat dry-year risk, a pumped storage system could be built. This is where water is pumped uphill when hydro lake inflows are plentiful, and used to generate electricity during dry periods.

The NZ Battery project is currently considering the potential for this in New Zealand, and debates such as whether we would use Site C's electricity offer relevant lessons.

 

Almost (but not quite) 100% renewable
Dry-year risk would be greatly reduced and there would be “greater greenhouse gas emissions savings” if the Interim Climate Change Committee’s (ICCC) 2019 recommendation to aim for 99% renewable electricity was adopted, rather than aiming for 100%.

A small amount of gas-peaking plant would therefore be retained. The ICCC said going from 99% to 100% renewable electricity by overbuilding would only avoid a very small amount of carbon emissions, at a very high cost.

Our modelling supports this view. The CCC’s draft advice on the issue also makes the point that, although 100% renewable electricity is the “desired end point”, timing is important to enable a smooth transition.

Despite these views, Energy Minister Megan Woods has said the government will be keeping the target of a 100% renewable electricity sector by 2030.

 

Impacts of climate change
In future, the electricity system will have to respond to changing climate patterns as well, becoming resilient to climate risks over time.

The National Institute of Water and Atmospheric Research predicts winds will increase in the South Island and decrease in the far north in coming decades.

Inflows to the biggest hydro lakes will get wetter (more rain in their headwaters), and their seasonality will change due to changes in the amount of snow in these catchments.

Our modelling shows the electricity system can adapt to those changing conditions. One good news story (unless you’re a skier) is that warmer temperatures will mean less snow storage at lower elevations, and therefore higher lake inflows in the big hydro catchments in winter, leading to a better match between times of high electricity demand and higher inflows.

 

The price is right
The modelling also shows the cost of generating electricity is not likely to increase, because the price of building new sources of renewable energy continues to fall globally.

Because the cost of building new renewables is now cheaper than non-renewables (such as coal-fired plants), investing in carbon-free electricity is increasingly compelling, and renewables are more likely to be built to meet new demand in the near term.

While New Zealand’s electricity system can enable the rapid decarbonisation of (at least) our transport and industrial heat sectors, international efforts like cleaning up Canada's electricity underline the need for certainty so the electricity industry can start building to meet demand everywhere.

Bipartisan cooperation at government level will be important to encourage significant investment in generation and transmission projects with long lead times and life expectancies, as analyses of climate policy and grid implications underscore in comparable markets.

Infrastructure and markets are needed to support demand response uptake, as well as certainty around the Tiwai exit in 2024 and whether pumped storage is likely to be built.

Our electricity system can support the rapid decarbonisation needed if New Zealand is to do its fair share globally to tackle climate change.

But sound planning, firm decisions and a supportive and relatively stable regulatory framework are all required before shovels can hit the ground.

 

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Electricity retailer Griddy's unusual plea to Texas customers: Leave now before you get a big bill

Texas wholesale electricity price spike disrupts ERCOT markets as Griddy and other retail energy providers face surge pricing; customers confront spot market exposure, fixed-rate plan switching, demand response appeals, and deep-freeze grid constraints across Texas.

 

Key Points

An extreme ERCOT market surge sending real-time rates to caps, exposing Griddy users and driving provider-switch pleas.

✅ Wholesale index plans pass through $9,000/MWh scarcity pricing.

✅ Retailers urge switching; some halt enrollments amid volatility.

✅ Demand response incentives and conservation pleas reduce load.

 

Some retail power companies in Texas are making an unusual plea to their customers amid a winter storm that has sent electricity prices skyrocketing: Please, leave us.

Power supplier, Griddy, told all 29,000 of its customers that they should switch to another provider as spot electricity prices soared to as high as $9,000 a megawatt-hour. Griddy’s customers are fully exposed to the real-time swings in wholesale power markets, so those who don’t leave soon will face extraordinarily high electricity bills.

“We made the unprecedented decision to tell our customers — whom we worked really hard to get — that they are better off in the near term with another provider,” said Michael Fallquist, chief executive officer of Griddy. “We want what’s right by our consumers, so we are encouraging them to leave. We believe that transparency and that honesty will bring them back” once prices return to normal.

Texas is home to the most competitive electricity market in America. Homeowners and businesses shopping for electricity churn power providers there like credit cards. In the face of such cutthroat competition, retail power providers in the region have grown accustomed to offering new customers incredibly low rates, incentives and, at least in Griddy’s case, unusual plans that allow customers to pay wholesale power prices as opposed to fixed ones.

The ruthless nature of the business has power traders speculating over which firms might have been caught short this week in the most dramatic run-up in spot power prices they’ve ever seen, and even talk of a market bailout has surfaced.

Not all companies are asking customers to leave. Others are just pleading for them to cut back to reduce blackout risks during extreme weather.

Pulse Power, based in The Woodlands, Texas, is offering customers a chance to win a Tesla Model 3, or free electricity for up to a year if they reduce their power usage by 10% in the coming days. Austin-based Bulb is offering $2 per kilowatts-hour, up to $200, for any energy customers save.

Griddy, however, is in a different position. Its service is simple — and controversial. Members pay a $9.99 monthly fee and then pay the cost of spot power traded on Texas’s power grid based on the time of day they use it. Earlier this month, that meant customers were saving money — and at times even getting paid — to use electricity at night. But in recent days, the cost of their power has soared from about 5 to 6 cents a kilowatt-hour to $1 or more. That’s when Fallquist knew it was time to urge his customers to leave.

“I can tell you it was probably one of the hardest decisions we’ve ever made,” he said. “Nobody ever wants to see customers go.”

Griddy isn’t the only one out there actively encouraging its customers to leave. People were posting similar pleas on Twitter over the holiday weekend from other Texas utilities and retail power providers offering everything from $100 rebates to waived cancellation fees as incentives to switch.

Customers may not even be able to switch. Rizwan Nabi, president of energy consultancy Riz Energy in Houston, said several power providers in Texas have told him they aren’t accepting new customers due to this week’s volatile prices, while grid improvements are debated statewide.

Hector Torres, an energy trader in Texas, who is a Griddy customer himself, said he tried to switch services over the long weekend but couldn’t find a company willing to take him until Wednesday, when the weather is forecast to turn warmer.

 

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Was there another reason for electricity shutdowns in California?

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

 

Key Points

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

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

✅ PSPS mitigates ignition from damaged transmission infrastructure.

✅ Baseload diversity improves resilience during high-wind events.

 

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

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

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

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

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

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

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

 

Wind Speed Limits

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

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

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

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

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

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

 

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