California Heat Wave Grid Emergency sees CAISO issue Stage 3 alerts as record demand, extreme heat, and climate change strain renewable energy; conservation efforts avert rolling blackouts and protect grid reliability statewide.
Key Points
A grid emergency in California's heat wave, with CAISO Stage 3 alerts amid record demand and risk of rolling blackouts.
✅ CAISO triggered Stage 3 alerts, then downgraded by 8 pm PT
✅ Record 52,061 MW demand; conservation reduced grid stress
✅ Extreme heat and climate change heightened outage risks
California has avoided ordering rolling blackouts after electricity demand reached a record-high Tuesday night from excessive heat across the state, even as energy experts warn the U.S. grid faces mounting climate stresses.
The California Independent System Operator, which oversees the state’s electrical grid, imposed its highest level energy emergency on Tuesday, a step that comes before ordering rolling blackouts and allows the state to access emergency power sources.
The Office of Emergency Services also sent a text alert to residents requesting them to conserve power. The operator downgraded the Stage 3 alert around 8:00 p.m. PT on Tuesday and said that “consumer conservation played a big part in protecting electric grid reliability,” and in bolstering grid resilience overall.
The state capital of Sacramento reached 116 degrees Fahrenheit on Tuesday, according to the National Weather Service, surpassing a record that was set almost 100 years ago. And nearly a half-dozen cities in the San Francisco Bay Area tied or set all-time highs, the agency said.
CAISO said peak power demand on Tuesday reached 52,061 megawatts, surpassing a previous high of 50,270 megawatts on July 24, 2006, while nearby B.C. electricity demand has also hit records during extreme weather.
While the operator did not order rolling blackouts, three Northern California cities saw brief power outages, and severe storms have caused similar disruptions statewide in recent months. As of 7:00 am PT on Wednesday, nearly 8,000 customers in California were without power, according to PowerOutage.us.
Gov. Gavin Newsom, in a Twitter video on Tuesday, warned the temperatures across California were unprecedented and the state is headed into the worst part of the heat wave, which is on track to be the hottest and longest on record for September.
“The risk for outages is real and it’s immediate,” Newsom said. “These triple-digit temperatures throughout much of the state are leading, not surprisingly, to record demand on the energy grid.”
The governor urged residents to pre-cool their homes earlier in the day when more power is available and turn thermostats to 78 degrees or higher after 4:00 pm PT. “Everyone has to do their part to help step up for just a few more days,” Newsom said.
The possibility for widespread outages reflects how power grids in California and other states are becoming more vulnerable to climate-related disasters such as heat waves, storms and wildfires across California.
California, which has set a goal to transition to 100% carbon-free electricity by 2045, has shuttered a slew of gas power plants in the past few years, leaving the state increasingly dependent on solar energy.
At times, the state has produced a clean energy surplus during peak solar generation, underscoring the challenges of balancing supply and demand.
The megadrought in the American West has generated the driest two decades in the region in at least 1,200 years, and human-caused climate change has fueled the problem, scientists said earlier this year. Conditions will likely continue through 2022 and persist for years.
Berlin Electric Utility APPA Safety Award recognizes Gold Designation performance in public power, highlighting OSHA-aligned incident rates, robust safety culture, worker safety training, and operational reliability that keeps the community's electric service resilient.
Key Points
A national honor for Berlin's Gold Designation recognizing safety performance, worker protection, and reliable service.
✅ Gold Designation in 15,000-29,999 worker hours APPA category
✅ OSHA-based incident rate and robust safety culture
✅ Training, PPE, and reliability focus in public power operations
The Town of Berlin Electric Utility Department has been recognized for its outstanding safety practices with the prestigious Safety Award of Excellence from the American Public Power Association (APPA), a distinction also reflected in Medicine Hat Electric Utility for health and safety excellence, highlighting industry-wide commitment to worker protection.
Recognition for Excellence
In an era when workplace safety is a critical concern, with organizations highlighting leadership in worker safety across the sector, the Town of Berlin Electric Utility Department’s achievement stands out. The department earned the Gold Designation award in the category for utilities with 15,000 to 29,999 worker hours of annual worker exposure. This category is part of the APPA’s annual Safety Awards, which are designed to recognize the safety performance of public power utilities across the United States.
Out of more than 200 utilities that participated in the 2024 Safety Awards, Berlin's Electric Utility Department distinguished itself with an exemplary safety record. The utility’s ranking was based on its low incidence of work-related injuries and illnesses, alongside its robust safety programs and strong safety culture.
What the Award Represents
The Safety Award of Excellence is given to utilities that demonstrate effective safety protocols and practices over the course of the year. The APPA evaluates utilities based on their incident rate, which is calculated using the number of work-related reportable injuries or illnesses relative to worker hours. This measurement adheres to guidelines established by the Occupational Safety and Health Administration (OSHA), ensuring a standardized approach to assessing safety.
For the Town of Berlin Electric Utility Department, achieving the Gold Designation award signifies a year of outstanding safety performance. The award reflects the department’s dedication to preventing accidents and creating a work environment where safety is prioritized at every level.
Why Safety Matters
For utilities like the one in Berlin, safety is not just about preventing injuries—it's about fostering a culture of care and responsibility. Electric utility workers face unique and significant risks, ranging from the dangers of working with high-voltage systems, including hazards near downed power lines that require extreme caution, to the physical demands of the job. A utility’s ability to minimize these risks and keep its workforce safe is a direct reflection of its safety practices, training, and overall management.
The commitment to safety extends beyond just the immediate work environment. Utilities that place a high value on safety typically invest in ongoing training, safety gear, and processes, and even contingency measures like staff living on site during outbreaks, that ensure all employees are well-prepared to handle the challenges of their roles. The Town of Berlin Electric Utility Department has taken these steps seriously, providing its workers with the resources they need to stay safe while maintaining the power supply for the local community.
The Importance of Worker Safety in Public Power
The American Public Power Association’s Safety Award program highlights the best practices in public utilities, which, as the U.S. grid overseer's pandemic warning reminded the sector, play a crucial role in providing essential services to communities across the country. Public power utilities, like Berlin’s, are governed by local or municipal entities rather than for-profit corporations, which often allows them to have a closer relationship with their communities. As a result, these utilities often go above and beyond when it comes to worker safety, understanding that the well-being of employees directly impacts the quality of service provided to residents.
For the Town of Berlin, this award not only highlights the utility's commitment to its employees but also reinforces the importance of the work that public utilities do in keeping communities safe and powered. Berlin's recognition underscores the significance of maintaining a safe work environment, especially when the safety of first responders and utility workers, as seen when nuclear plant workers raised concerns over virus precautions, directly impacts the public’s access to reliable services.
What’s Next for Berlin’s Electric Utility Department
Receiving the Safety Award of Excellence is a remarkable achievement, but for the Town of Berlin Electric Utility Department, it’s not the end of their safety journey—it’s just one more step in their ongoing commitment to improvement. The department’s leadership, including the safety team, has emphasized the importance of continually evaluating and enhancing safety protocols to stay ahead of potential risks. This includes adopting new safety technologies, refining training programs, and ensuring that all employees are involved in the process of safety.
As the Town of Berlin looks forward to the future, its focus on worker safety will remain a top priority. Maintaining this level of safety is not only crucial for the health and well-being of employees but also for ensuring the continued success of the community’s utility services.
Community Impact
This recognition also serves as an example for other utilities in the region and across the country. By prioritizing safety, the Town of Berlin Electric Utility Department sets a standard that other utilities can aspire to. In a time when worker safety is more important than ever, Berlin’s commitment to best practices provides a model for others to follow.
Ultimately, the safety of utility workers is a reflection of a community’s dedication to its workforce and its commitment to providing reliable, uninterrupted services. For the residents of Berlin, the recognition of their local electric utility department’s safety practices means that they can continue to rely on a safe, secure, and resilient power infrastructure, while staying mindful of home risks such as overheated power strips that can spark fires.
Covid-19 Energy Transition and Machine Learning reshape climate change policy, electricity planning, and grid operations, from demand forecasting and decarbonization strategies in Europe to scalable electrification modeling and renewable integration across Africa.
Key Points
How the pandemic reshapes energy policy and how ML improves planning, demand forecasts, and grid reliability in Africa.
✅ Pandemic-driven demand shifts strain grid operations and markets
✅ ML boosts demand prediction, electrification, and grid reliability in Africa
The impact of Covid-19 on the energy system was discussed in an online climate change workshop that also considered how machine learning can help electricity planning in Africa.
This year’s International Conference on Learning Representations event included a workshop held by the Climate Change AI group of academics and artificial intelligence industry representatives, which considered how machine learning can help tackle climate change and highlighted advances by European electricity prediction specialists working in this field.
Bjarne Steffen, senior researcher at the energy politics group at ETH Zürich, shared his insights at the workshop on how Covid-19 and the accompanying economic crisis are affecting recently introduced ‘green’ policies. “The crisis hit at a time when energy policies were experiencing increasing momentum towards climate action, especially in Europe, and in proposals to invest in smarter electricity infrastructure for long-term resilience,” said Steffen, who added the coronavirus pandemic has cast into doubt the implementation of such progressive policies.
The academic said there was a risk of overreacting to the public health crisis, as far as progress towards climate change goals was concerned.
Lobbying
“Many interest groups from carbon-intensive industries are pushing to remove the emissions trading system and other green policies,” said Steffen. “In cases where those policies are having a serious impact on carbon-emitting industries, governments should offer temporary waivers during this temporary crisis, instead of overhauling the regulatory structure.”
However, the ETH Zürich researcher said any temptation to impose environmental conditions to bail-outs for carbon-intensive industries should be resisted. “While it is tempting to push a green agenda in the relief packages, tying short-term environmental conditions to bail-outs is impractical, given the uncertainty in how long this crisis will last,” he said. “It is better to include provisions that will give more control over future decisions to decarbonize industries, such as the government taking equity shares in companies.”
Steffen shared with pv magazine readers an article published in Joule which can be accessed here, and which articulates his arguments about how Covid-19 could affect the energy transition.
Covid-19 in the U.K.
The electricity system in the U.K. is also being affected by Covid-19, even as the U.S. electric grid grapples with climate risks, according to Jack Kelly, founder of London-based, not-for-profit, greenhouse gas emission reduction research laboratory Open Climate Fix.
“The crisis has reduced overall electricity use in the U.K.,” said Kelly. “Residential use has increased but this has not offset reductions in commercial and industrial loads.”
Steve Wallace, a power system manager at British electricity system operator National Grid ESO recently told U.K. broadcaster the BBC electricity demand has fallen 15-20% across the U.K. The National Grid ESO blog has stated the fall-off makes managing grid functions such as voltage regulation more challenging.
Open Climate Fix’s Kelly noted even events such as a nationally-coordinated round of applause for key workers was followed by a dramatic surge in demand, stating: “On April 16, the National Grid saw a nearly 1 GW spike in electricity demand over 10 minutes after everyone finished clapping for healthcare workers and went about the rest of their evenings.”
Climate Change AI workshop panelists also discussed the impact machine learning could have on improving electricity planning in Africa. The Electricity Growth and Use in Developing Economies (e-Guide) initiative funded by fossil fuel philanthropic organization the Rockefeller Foundation aims to use data to improve the planning and operation of electricity systems in developing countries.
E-Guide members Nathan Williams, an assistant professor at the Rochester Institute of Technology (RIT) in New York state, and Simone Fobi, a PhD student at Columbia University in NYC, spoke about their work at the Climate Change AI workshop, which closed on Thursday. Williams emphasized the importance of demand prediction, saying: “Uncertainty around current and future electricity consumption leads to inefficient planning. The weak link for energy planning tools is the poor quality of demand data.”
Fobi said: “We are trying to use machine learning to make use of lower-quality data and still be able to make strong predictions.”
The market maturity of individual solar home systems and PV mini-grids in Africa mean more complex electrification plan modeling is required, similar to integrating AI data centers into Canada's grids at scale.
Modeling
“When we are doing [electricity] access planning, we are trying to figure out where the demand will be and how much demand will exist so we can propose the right technology,” added Fobi. “This makes demand estimation crucial to efficient planning.”
Unlike many traditional modeling approaches, machine learning is scalable and transferable. Rochester’s Williams has been using data from nations such as Kenya, which are more advanced in their electrification efforts, to train machine learning models to make predictions to guide electrification efforts in countries which are not as far down the track.
Williams also discussed work being undertaken by e-Guide members at the Colorado School of Mines, which uses nighttime satellite imagery and machine learning to assess the reliability of grid infrastructure in India, where new algorithms to prevent ransomware-induced blackouts are also advancing.
Rural power
Another e-Guide project, led by Jay Taneja at the University of Massachusetts, Amherst – and co-funded by the Energy and Economic Growth program on development spending based at Berkeley – uses satellite imagery to identify productive uses of electricity in rural areas by detecting pollution signals from diesel irrigation pumps.
Though good quality data is often not readily available for Africa, Williams added, it does exist.
“We have spent years developing trusting relationships with utilities,” said the RIT academic. “Once our partners realize the value proposition we can offer, they are enthusiastic about sharing their data … We can’t do machine learning without high-quality data and this requires that organizations can effectively collect, organize, store and work with data. Data can transform the electricity sector, as shown by Canadian projects to use AI for energy savings, but capacity building is crucial.”
Belarus Nuclear Power Infrastructure Review evaluates IAEA INIR Phase 3 readiness at Ostrovets NPP, VVER-1200 reactors, legal and regulatory framework, commissioning, safety, emergency preparedness, and energy diversification in a low-carbon program.
Key Points
An IAEA INIR Phase 3 assessment of Belarus readiness to commission and operate the Ostrovets NPP with VVER-1200 units.
✅ Reviews legal, regulatory, and institutional arrangements
✅ Confirms Phase 3 readiness for safe commissioning and operation
✅ Highlights good practices in peer reviews and emergency planning
An International Atomic Energy Agency (IAEA) team of experts today concluded a 12-day mission to Belarus to review its infrastructure development for a nuclear power programme. The Integrated Nuclear Infrastructure Review (INIR) was carried out at the invitation of the Government of Belarus.
Belarus, seeking to diversify its energy production with a reliable low-carbon source, and aware of the benefits of energy storage for grid flexibility, is building its first nuclear power plant (NPP) at the Ostrovets site, about 130 km north-west of the capital Minsk. The country has engaged with the Russian Federation to construct and commission two VVER-1200 pressurised water reactors at this site and expects the first unit to be connected to the grid this year.
The INIR mission reviewed the status of nuclear infrastructure development using the Phase 3 conditions of the IAEA’s Milestones Approach. The Ministry of Energy of Belarus hosted the mission.
The INIR team said Belarus is close to completing the required nuclear power infrastructure for starting the operation of its first NPP. The team made recommendations and suggestions aimed at assisting Belarus in making further progress in its readiness to commission and operate it, including planning for integration with variable renewables, as advances in new wind turbines are being deployed elsewhere to strengthen the overall energy mix.
“This mission marks an important step for Belarus in its preparations for the introduction of nuclear power,” said team leader Milko Kovachev, Head of the IAEA’s Nuclear Infrastructure Development Section. “We met well-prepared, motivated and competent professionals ready to openly discuss all infrastructure issues. The team saw a clear drive to meet the objectives of the programme and deliver benefits to the Belarusian people, such as supporting the country’s economic development, including growth in EV battery manufacturing sectors.”
The team comprised one expert from Algeria and two experts from the United Kingdom, as well as seven IAEA staff. It reviewed the status of 19 nuclear infrastructure issues using the IAEA evaluation methodology for Phase 3 of the Milestones Approach, noting that regional integration via an electricity highway can shape planning assumptions as well. It was the second INIR mission to Belarus, who hosted a mission covering Phases 1 and 2 in 2012.
Prior to the latest mission, Belarus prepared a Self-Evaluation Report covering all infrastructure issues and submitted the report and supporting documents to the IAEA.
The team highlighted areas where further actions would benefit Belarus, including the need to improve institutional arrangements and the legal and regulatory framework, drawing on international examples of streamlined licensing for advanced reactors to ensure a stable and predictable environment for the programme; and to finalize the remaining arrangements needed for sustainable operation of the nuclear power plant.
The team also identified good practices that would benefit other countries developing nuclear power in the areas of programme and project coordination, the use of independent peer reviews, cooperation with regulators from other countries, engagement with international stakeholders and emergency preparedness, and awareness of regional initiatives such as new electricity interconnectors that can enhance system resilience.
Mikhail Chudakov, IAEA Deputy Director General and Head of the Department of Nuclear Energy attended the Mission’s closing meeting. “Developing the infrastructure required for a nuclear power programme requires significant financial and human resources, and long lead times for preparation and the approval of major transmission projects that support clean power flows, and the construction activities,” he said. “Belarus has made commendable progress since the decision to launch a nuclear power programme 10 years ago.”
“Hosting the INIR mission, Belarus demonstrated its transparency and genuine interest to receive an objective professional assessment of the readiness of its nuclear power infrastructure for the commissioning of the country’s first nuclear power plant,” said Mikhail Mikhadyuk, Deputy Minister of Energy of the Republic of Belarus. ”The recommendations and suggestions we received will be an important guidance for our continuous efforts aimed at ensuring the highest level of safety and reliability of the Belarusian NPP."
Karpowership LNG powership in Senegal will supply 15% of the grid, a 235 MW floating power plant bound for Dakar, enabling fast deployment, base-load electricity, and cleaner natural gas generation for West Africa.
Key Points
A 235 MW floating plant supplying 15% of Senegal's grid with fast, reliable, lower-emission LNG electricity.
✅ Rapid deployment: commercial operations expected early October
✅ Cleaner natural gas conversion planned after six months
Turkey's Karpowership company, the designer and builder of the world's first floating power plants and the global brand of Karadeniz Holding, will meet 15% of Senegal's electricity needs from liquefied natural gas (LNG) with the 235-megawatt (MW) powership Ayşegül Sultan, which started its voyage from Turkey to Senegal, where an African Development Bank review of a coal plant is underway, on Sunday.
Karpowership, operating 22 floating power plants in more than 10 countries around the world, where France's first offshore wind turbine is now producing electricity, has invested over $5 billion in this area.
In a statement to members of the press at Karmarine Shipyard, Karpowership Trade Group Chair Zeynep Harezi said they aimed to provide affordable electricity to countries in need of electricity quickly and reliably, as projects like the Egypt-Saudi power link expand regional grids, adding that they could commission energy ships capable of generating the base electric charge of the countries, as tidal power in Nova Scotia begins supplying the grid, in a period of about a month.
Harezi recalled that Karpowership commissioned the first floating energy ship in 2007 in Iraq, followed by Lebanon, Ghana, Indonesia, Mozambique, Zambia, Gambia, Sierra Leone, Sudan, Cuba, Guinea Bissau and Senegal, while Scottish tidal power demonstrates marine potential as well. "We meet the electricity needs of 34 million people in many countries," she stressed. Harezi stated that the energy ships, all designed and produced by Turkish engineers, use liquid fuel, but all ships can covert to the second fuel.
Considering the impact of electricity production on the environment, Harezi noted that they plan to convert the entire fleet from liquid fuel to natural gas, with complementary approaches like power-to-gas in Europe helping integrate renewables. "With a capacity of 480 megawatts each, the world's largest floating energy vessels operate in Indonesia and Ghana. The conversion to gas has been completed in our project in Indonesia. We have also initiated the conversion of the Ghana vessel into gas," she said.
Harezi explained that they would continue to convert their fleets to natural gas in the coming period. "Our 235-MW floating electric vessel, the Ayşegül Sultan, sets sail today to meet 15% of Senegal's electricity needs on its own. After an approximately 20-day cruise, the vessel will reach Dakar, the capital of Senegal, and will begin commercial operation in early October," Harezi continued. "We plan to use liquid fuel as bridging fuel in the first six months. At the end of the first six months, we will start to produce electricity from LNG on our ship. Thus, Ayşegül Sultan will be the first project to generate electricity from LNG in Africa, while the world's most powerful tidal turbine is delivering power to the grid, officials said. Our floating power plant to be sent to Mozambique is designed to generate electricity from LNG. It is also scheduled to start operations in the next year."
Rolls-Royce SMR UK Approval underscores nuclear innovation as regulators review a 470 MW factory-built modular reactor, aiming for grid power by 2029 to boost energy security, cut fossil fuels, and accelerate decarbonization.
Key Points
UK regulatory clearance for Rolls-Royce's 470 MW modular reactor, targeting grid power by 2029 to support clean energy.
✅ UK design approval expected by mid 2024
✅ First 470 MW unit aims for grid power by 2029
✅ Modular, factory-built; est. £1.8b per 10-acre site
A Rolls-Royce (RR.L) design for a small modular nuclear reactor (SMR) will likely receive UK regulatory approval by mid-2024, reflecting progress seen in the US NRC safety evaluation for NuScale as a regulatory benchmark, and be able to produce grid power by 2029, Paul Stein, chairman of Rolls-Royce Small Modular Reactors.
The British government asked its nuclear regulator to start the approval process in March, in line with the UK's green industrial revolution agenda, having backed Rolls-Royce’s $546 million funding round in November to develop the country’s first SMR reactor.
Policymakers hope SMRs will help cut dependence on fossil fuels and lower carbon emissions, as projects like Ontario's first SMR move ahead in Canada, showing momentum.
Speaking to Reuters in an interview conducted virtually, Stein said the regulatory “process has been kicked off, amid broader moves such as a Canadian SMR initiative to coordinate development, and will likely be complete in the middle of 2024.
“We are trying to work with the UK Government, and others to get going now placing orders, echoing expansions like Darlington SMR plans in Ontario, so we can get power on grid by 2029.”
In the meantime, Rolls-Royce will start manufacturing parts of the design that are most unlikely to change, while advancing partnerships like a MoU with Exelon to support deployment, Stein added.
Each 470 megawatt (MW) SMR unit costs 1.8 billion pounds ($2.34 billion) and would be built on a 10-acre site, the size of around 10 football fields, though projects in New Brunswick SMR debate have prompted questions about costs and timelines.
Unlike traditional reactors, SMRs are cheaper and quicker to build and can also be deployed on ships and aircraft. Their “modular” format means they can be shipped by container from the factory and installed relatively quickly on any proposed site.
Boeing 787 More-Electric Architecture replaces pneumatics with bleedless pressurization, VFSG starter-generators, electric brakes, and heated wing anti-ice, leveraging APU, RAT, batteries, and airport ground power for efficient, redundant electrical power distribution.
Key Points
An integrated, bleedless electrical system powering start, pressurization, brakes, and anti-ice via VFSGs, APU and RAT.
✅ VFSGs start engines, then generate 235Vac variable-frequency power
✅ Bleedless pressurization, electric anti-ice improve fuel efficiency
✅ Electric brakes cut hydraulic weight and simplify maintenance
The 787 Dreamliner is different to most commercial aircraft flying the skies today. On the surface it may seem pretty similar to the likes of the 777 and A350, but get under the skin and it’s a whole different aircraft.
When Boeing designed the 787, in order to make it as fuel efficient as possible, it had to completely shake up the way some of the normal aircraft systems operated. Traditionally, systems such as the pressurization, engine start and wing anti-ice were powered by pneumatics. The wheel brakes were powered by the hydraulics. These essential systems required a lot of physical architecture and with that comes weight and maintenance. This got engineers thinking.
What if the brakes didn’t need the hydraulics? What if the engines could be started without the pneumatic system? What if the pressurisation system didn’t need bleed air from the engines? Imagine if all these systems could be powered electrically… so that’s what they did.
Power sources
The 787 uses a lot of electricity. Therefore, to keep up with the demand, it has a number of sources of power, much as grid operators track supply on the GB energy dashboard to balance loads. Depending on whether the aircraft is on the ground with its engines off or in the air with both engines running, different combinations of the power sources are used.
Engine starter/generators
The main source of power comes from four 235Vac variable frequency engine starter/generators (VFSGs). There are two of these in each engine. These function as electrically powered starter motors for the engine start, and once the engine is running, then act as engine driven generators.
The generators in the left engine are designated as L1 and L2, the two in the right engine are R1 and R2. They are connected to their respective engine gearbox to generate electrical power directly proportional to the engine speed. With the engines running, the generators provide electrical power to all the aircraft systems.
APU starter/generators
In the tail of most commercial aircraft sits a small engine, the Auxiliary Power Unit (APU). While this does not provide any power for aircraft propulsion, it does provide electrics for when the engines are not running.
The APU of the 787 has the same generators as each of the engines — two 235Vac VFSGs, designated L and R. They act as starter motors to get the APU going and once running, then act as generators. The power generated is once again directly proportional to the APU speed.
The APU not only provides power to the aircraft on the ground when the engines are switched off, but it can also provide power in flight should there be a problem with one of the engine generators.
Battery power
The aircraft has one main battery and one APU battery. The latter is quite basic, providing power to start the APU and for some of the external aircraft lighting.
The main battery is there to power the aircraft up when everything has been switched off and also in cases of extreme electrical failure in flight, and in the grid context, alternatives such as gravity power storage are being explored for long-duration resilience. It provides power to start the APU, acts as a back-up for the brakes and also feeds the captain’s flight instruments until the Ram Air Turbine deploys.
Ram air turbine (RAT) generator
When you need this, you’re really not having a great day. The RAT is a small propeller which automatically drops out of the underside of the aircraft in the event of a double engine failure (or when all three hydraulics system pressures are low). It can also be deployed manually by pressing a switch in the flight deck.
Once deployed into the airflow, the RAT spins up and turns the RAT generator. This provides enough electrical power to operate the captain’s flight instruments and other essentials items for communication, navigation and flight controls.
External power
Using the APU on the ground for electrics is fine, but they do tend to be quite noisy. Not great for airports wishing to keep their noise footprint down. To enable aircraft to be powered without the APU, most big airports will have a ground power system drawing from national grids, including output from facilities such as Barakah Unit 1 as part of the mix. Large cables from the airport power supply connect 115Vac to the aircraft and allow pilots to shut down the APU. This not only keeps the noise down but also saves on the fuel which the APU would use.
The 787 has three external power inputs — two at the front and one at the rear. The forward system is used to power systems required for ground operations such as lighting, cargo door operation and some cabin systems. If only one forward power source is connected, only very limited functions will be available.
The aft external power is only used when the ground power is required for engine start.
Circuit breakers
Most flight decks you visit will have the back wall covered in circuit breakers — CBs. If there is a problem with a system, the circuit breaker may “pop” to preserve the aircraft electrical system. If a particular system is not working, part of the engineers procedure may require them to pull and “collar” a CB — placing a small ring around the CB to stop it from being pushed back in. However, on the 787 there are no physical circuit breakers. You’ve guessed it, they’re electric.
Within the Multi Function Display screen is the Circuit Breaker Indication and Control (CBIC). From here, engineers and pilots are able to access all the “CBs” which would normally be on the back wall of the flight deck. If an operational procedure requires it, engineers are able to electrically pull and collar a CB giving the same result as a conventional CB.
Not only does this mean that the there are no physical CBs which may need replacing, it also creates space behind the flight deck which can be utilised for the galley area and cabin.
A normal flight
While it’s useful to have all these systems, they are never all used at the same time, and, as the power sector’s COVID-19 mitigation strategies showed, resilience planning matters across operations. Depending on the stage of the flight, different power sources will be used, sometimes in conjunction with others, to supply the required power.
On the ground
When we arrive at the aircraft, more often than not the aircraft is plugged into the external power with the APU off. Electricity is the blood of the 787 and it doesn’t like to be without a good supply constantly pumping through its system, and, as seen in NYC electric rhythms during COVID-19, demand patterns can shift quickly. Ground staff will connect two forward external power sources, as this enables us to operate the maximum number of systems as we prepare the aircraft for departure.
Whilst connected to the external source, there is not enough power to run the air conditioning system. As a result, whilst the APU is off, air conditioning is provided by Preconditioned Air (PCA) units on the ground. These connect to the aircraft by a pipe and pump cool air into the cabin to keep the temperature at a comfortable level.
APU start
As we near departure time, we need to start making some changes to the configuration of the electrical system. Before we can push back , the external power needs to be disconnected — the airports don’t take too kindly to us taking their cables with us — and since that supply ultimately comes from the grid, projects like the Bruce Power upgrade increase available capacity during peaks, but we need to generate our own power before we start the engines so to do this, we use the APU.
The APU, like any engine, takes a little time to start up, around 90 seconds or so. If you remember from before, the external power only supplies 115Vac whereas the two VFSGs in the APU each provide 235Vac. As a result, as soon as the APU is running, it automatically takes over the running of the electrical systems. The ground staff are then clear to disconnect the ground power.
If you read my article on how the 787 is pressurised, you’ll know that it’s powered by the electrical system. As soon as the APU is supplying the electricity, there is enough power to run the aircraft air conditioning. The PCA can then be removed.
Engine start
Once all doors and hatches are closed, external cables and pipes have been removed and the APU is running, we’re ready to push back from the gate and start our engines. Both engines are normally started at the same time, unless the outside air temperature is below 5°C.
On other aircraft types, the engines require high pressure air from the APU to turn the starter in the engine. This requires a lot of power from the APU and is also quite noisy. On the 787, the engine start is entirely electrical.
Power is drawn from the APU and feeds the VFSGs in the engines. If you remember from earlier, these fist act as starter motors. The starter motor starts the turn the turbines in the middle of the engine. These in turn start to turn the forward stages of the engine. Once there is enough airflow through the engine, and the fuel is igniting, there is enough energy to continue running itself.
After start
Once the engine is running, the VFSGs stop acting as starter motors and revert to acting as generators. As these generators are the preferred power source, they automatically take over the running of the electrical systems from the APU, which can then be switched off. The aircraft is now in the desired configuration for flight, with the 4 VFSGs in both engines providing all the power the aircraft needs.
As the aircraft moves away towards the runway, another electrically powered system is used — the brakes. On other aircraft types, the brakes are powered by the hydraulics system. This requires extra pipe work and the associated weight that goes with that. Hydraulically powered brake units can also be time consuming to replace.
By having electric brakes, the 787 is able to reduce the weight of the hydraulics system and it also makes it easier to change brake units. “Plug in and play” brakes are far quicker to change, keeping maintenance costs down and reducing flight delays.
In-flight
Another system which is powered electrically on the 787 is the anti-ice system. As aircraft fly though clouds in cold temperatures, ice can build up along the leading edge of the wing. As this reduces the efficiency of the the wing, we need to get rid of this.
Other aircraft types use hot air from the engines to melt it. On the 787, we have electrically powered pads along the leading edge which heat up to melt the ice.
Not only does this keep more power in the engines, but it also reduces the drag created as the hot air leaves the structure of the wing. A double win for fuel savings.
Once on the ground at the destination, it’s time to start thinking about the electrical configuration again. As we make our way to the gate, we start the APU in preparation for the engine shut down. However, because the engine generators have a high priority than the APU generators, the APU does not automatically take over. Instead, an indication on the EICAS shows APU RUNNING, to inform us that the APU is ready to take the electrical load.
Shutdown
With the park brake set, it’s time to shut the engines down. A final check that the APU is indeed running is made before moving the engine control switches to shut off. Plunging the cabin into darkness isn’t a smooth move. As the engines are shut down, the APU automatically takes over the power supply for the aircraft. Once the ground staff have connected the external power, we then have the option to also shut down the APU.
However, before doing this, we consider the cabin environment. If there is no PCA available and it’s hot outside, without the APU the cabin temperature will rise pretty quickly. In situations like this we’ll wait until all the passengers are off the aircraft until we shut down the APU.
Once on external power, the full flight cycle is complete. The aircraft can now be cleaned and catered, ready for the next crew to take over.
Bottom line
Electricity is a fundamental part of operating the 787. Even when there are no passengers on board, some power is required to keep the systems running, ready for the arrival of the next crew. As we prepare the aircraft for departure and start the engines, various methods of powering the aircraft are used.
The aircraft has six electrical generators, of which only four are used in normal flights. Should one fail, there are back-ups available. Should these back-ups fail, there are back-ups for the back-ups in the form of the battery. Should this back-up fail, there is yet another layer of contingency in the form of the RAT. A highly unlikely event.
The 787 was built around improving efficiency and lowering carbon emissions whilst ensuring unrivalled levels safety, and, in the wider energy landscape, perspectives like nuclear beyond electricity highlight complementary paths to decarbonization — a mission it’s able to achieve on hundreds of flights every single day.
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