The North American Electric Reliability Council's (NERC) Board of Trustees approved the collection of the Phase I Transmission Availability Data System (TADS) data beginning in calendar year 2008.
TADS will collect transmission outage data in a common format for:
• AC circuits ≥200kV overhead and underground)
• Transformers with ≥200 kV low-side
• AC/DC back-to-back converters with ≥200 kV AC on both sides
• DC circuits with ≥ ±200 kV DC voltage
NERC will use the information to develop transmission metrics that analyze outage frequency, duration, causes, and many other factors related to transmission outages. NERC will also issue an annual public report showing aggregate metrics for each NERC region, and each transmission owner reporting TADS data will be provided a confidential copy of the same metrics for its facilities.
While TADS is not intended to provide determinative performance measures, it will be used to quantify certain performance aspects. In addition to collecting simple transmission equipment availability, TADS will collect detailed information about individual outage events that, when analyzed at the regional and NERC level, will provide data that may be used to improve reliability. Specific equipment outages will be linked to disturbance reports filed with NERC, enabling better association of transmission outages with load and generation outages.
Additionally, outages by one transmission owner will now be tracked to outages of other transmission owners so that any relationship between multiple outages can be established.
UK EV Per-Mile Taxes are reshaping road pricing and vehicle taxation for electric cars, raising fairness concerns, climate policy questions, and funding needs for infrastructure and charging networks across the country.
Key Points
They are per-mile road charges on EVs to fund infrastructure, raising fairness, emissions, and vehicle taxation concerns.
✅ Propose tax relief or credits for EV owners
✅ Consider emission-based road user charging
✅ Invest in charging networks and road infrastructure
As the UK continues its push towards a greener future with increased adoption of electric vehicles (EVs) and surging EV interest during supply disruptions, a growing number of electric car drivers are voicing their frustration over the current tax system. The debate centers around the per-mile vehicle taxes that are being proposed and implemented, which many argue are unfairly burdensome on EV owners. This issue has sparked a broader campaign advocating for a more equitable approach to vehicle taxation, one that reflects the evolving landscape of transportation and environmental policy.
Rising Costs for Electric Car Owners
Electric vehicles have been hailed as a crucial component in the UK’s strategy to reduce carbon emissions and combat climate change. Government incentives, such as grants for EV purchases and tax breaks, have been instrumental in encouraging the shift from petrol and diesel cars to cleaner alternatives, even as affordability concerns persist among many UK consumers. However, as the number of electric vehicles on the road grows, the financial dynamics of vehicle taxation are coming under scrutiny.
One of the key issues is the introduction and increase of per-mile vehicle taxes. While these taxes are designed to account for road usage and infrastructure costs, they have been met with resistance from EV drivers who argue that they are being disproportionately affected. Unlike traditional combustion engine vehicles, electric cars typically have lower running costs compared to petrol or diesel models and, in many cases, benefit from lower or zero emissions. Yet, the current tax system does not always reflect these advantages.
The Taxation Debate
The crux of the debate lies in how vehicle taxes are structured and implemented. Per-mile taxes are intended to ensure that all road users contribute fairly to the maintenance of transport infrastructure. However, the implementation of such taxes has raised concerns about fairness and affordability, particularly for those who have invested heavily in electric vehicles.
Critics argue that per-mile taxes do not adequately take into account the environmental benefits of driving an electric car, noting that the net impact depends on the electricity generation mix in each market. While EV owners are contributing to a cleaner environment by reducing emissions, they are also facing higher taxes that could undermine the financial benefits of their greener choice. This has led to calls for a reassessment of the tax system to ensure that it aligns with the UK’s climate goals and provides a fair deal for electric vehicle drivers.
Campaigns for Fairer Taxation
In response to these concerns, several advocacy groups and individual EV owners have launched campaigns calling for a more balanced approach to vehicle taxation. These campaigns emphasize the need for a system that supports the transition to electric vehicles and recognizes their role in reducing environmental impact, drawing on ambitious EV targets abroad as useful benchmarks.
Key proposals from these campaigns include:
Tax Relief for EV Owners: Advocates suggest providing targeted tax relief for electric vehicle owners to offset the costs of per-mile taxes. This could include subsidies or tax credits that acknowledge the environmental benefits of EVs and help to make up for higher road usage fees.
Emission-Based Taxation: An alternative approach is to design vehicle taxes based on emissions rather than mileage. This system would ensure that those driving high-emission vehicles contribute more to road maintenance, while EV owners, who are already reducing emissions, are not penalized.
Infrastructure Investments: Campaigners also call for increased investments in infrastructure that supports electric vehicles, such as charging networks and proper grid management practices that balance load. This would help to address concerns about the adequacy of current road maintenance and support the growing number of EVs on the road.
Government Response and Future Directions
The UK government faces the challenge of balancing revenue needs with environmental goals. While there is recognition of the need to update the tax system in light of increasing EV adoption, there is also a focus on ensuring that any changes are equitable and do not disincentivize the shift towards cleaner vehicles, while considering whether the UK grid can handle additional EV demand reliably.
Discussions are ongoing about how to best implement changes that address the concerns of electric vehicle owners while ensuring that the transportation infrastructure remains adequately funded. The outcome of these discussions will be critical in shaping the future of vehicle taxation in the UK and supporting the country’s broader environmental objectives.
Conclusion
As electric vehicle adoption continues to rise in the UK, the debate over vehicle taxation becomes increasingly important. The campaign for fairer per-mile taxes highlights the need for a tax system that supports the transition to cleaner transportation while also being fair to those who have made environmentally conscious choices. Balancing these factors will be key to achieving the UK’s climate goals and ensuring that all road users contribute equitably to the maintenance of transport infrastructure. The ongoing dialogue and policy adjustments will play a crucial role in shaping a sustainable and just future for transportation in the UK.
ESCC COVID-19 Response coordinates utilities, public power, and cooperatives to protect the energy grid and electricity reliability, aligning with DOE, DHS, CDC, FERC, and NERC on continuity of operations, mutual assistance, and supply chain resilience.
Key Points
An industry government effort ensuring reliability, operations continuity and supply chain stability during COVID-19.
✅ Focus on control centers, generation, quarantine access, mutual aid.
✅ Resource Guide supports localized decisions and supply chain resilience.
The nation’s investor-owned electric companies, public power utilities, and electric cooperatives are working together to protect the energy grid as the U.S. grid addresses COVID-19 challenges and ensure continued access to safe and reliable electricity during the COVID-19 global health crisis.
The electric power industry has been planning for years, including extensive disaster planning across utilities, for an emergency like the COVID-19 pandemic, as well as countless other types of emergencies, and the industry is coordinating closely with government partners through the Electricity Subsector Coordinating Council (ESCC) to ensure that organizations have the resources they need to keep the lights on.
The ESCC is holding high-level coordination calls twice a week with senior leadership from the Departments of Energy, Homeland Security, and Health and Human Services, the Centers for Disease Control and Prevention, the Federal Energy Regulatory Commission, and the North American Electric Reliability Corporation. These calls help ensure that industry and government work together to resolve any challenges that arise during this health emergency and that electricity remains safe for customers.
“Electricity and the energy grid are indispensable to our society, and one of our greatest strengths as an industry is our ability to convene and adapt quickly to changing circumstances and challenging events,” said Edison Electric Institute President Tom Kuhn. “Our industry plans for all types of contingencies, with examples such as local response planning, and strong industry-government coordination and cross-sector collaboration are critical to our planning and response. We appreciate the ongoing leadership and support of our government partners as we all respond to COVID-19 and power through this crisis together.”
The ESCC quickly mobilized and established strategic working groups dedicated to identifying and solving for short-, medium-, and long-term issues facing the industry during the COVID-19 pandemic, with utilities implementing necessary precautions to maintain service across regions.
The five current areas of focus are:
1. Continuity of operations at control centers, including on-site staff lockdowns when needed 2. Continuity of operations at generation facilities 3. Access to, and operations in, restricted or quarantined areas 4. Protocols for mutual assistance 5. Supply chain challenges
“The electric power industry has taken steps to prepare for the evolving coronavirus challenges, while maintaining our commitment to the communities we serve, including customer relief efforts announced by some providers,” said National Rural Electric Cooperative Association CEO Jim Matheson. “We have a strong track record of preparing for many kinds of emergencies that could impact the ability to generate and deliver electricity. While planning for this situation is unique from other business continuity planning, we are taking actions to prepare to operate with a smaller workforce, potential disruptions in the supply chain, and limited support services for an extended period of time.”
The ESCC has developed a COVID-19 Resource Guide linked here and available at electricitysubsector.org. This document was designed to support electric power industry leaders in making informed localized decisions in response to this evolving health crisis. The guide will evolve as additional recommended practices are identified and as more is learned about appropriate mitigation strategies.
“The American Public Power Association (APPA) continues to work with our communityowned public power members and our industry and government partners to gather and share upto-date information, best practices, and guidance to support them in safely maintaining operational integrity,” said APPA CEO Joy Ditto.
Hydro One-Avista Acquisition secures U.S. antitrust clearance under Hart-Scott-Rodino, pending approvals from state utility commissions, the FCC, and CFIUS, with prior FERC approval and shareholder vote supporting the cross-border utility merger.
Key Points
A $6.7B cross-border utility merger cleared under HSR, still awaiting state, FCC, and CFIUS approvals; FERC approved earlier.
✅ HSR waiting period expired; U.S. antitrust clearance obtained
✅ Approvals pending: state commissions, FCC, and CFIUS
✅ FERC and Avista shareholders have approved the transaction
Hydro One Ltd. says it has received antitrust clearance in the United States for its deal to acquire U.S. energy company Avista Corp., even as it sought to redesign customer bills in Ontario.
The Ontario-based utility says the 30-day waiting period under the Hart-Scott-Rodino Antitrust Improvements Act expired Thursday night.
Hydro One announced the friendly deal to acquire Avista last summer, amid customer backlash in some service areas, in an agreement that valued the company at $6.7 billion.
The deal still requires several other approvals, including those from utility commissions in Washington, Idaho, Oregon, Montana and Alaska.
Analysts also warned of political risk for Hydro One during this period, reflecting concerns about provincial influence.
The U.S. Federal Communications Commission must also sign off on the transaction, and although U.S. regulators later rejected the $6.7B takeover following review, clearance is required by the Committee on Foreign Investment in the United States.
The agreement has received approval from the U.S. Federal Energy Regulatory Commission as well as Avista shareholders, and it mirrored other cross-border deals such as Algonquin Power's acquisition of Empire District that closed in the sector.
Zaporizhzhia Nuclear Plant Restart signals new high-voltage transmission lines to Mariupol, Rosatom grid integration, and IAEA-monitored safety amid occupied territory risks, cooling system shortfalls after the Kakhovka dam collapse, and disputed international law.
Key Points
A Russian plan to reconnect and possibly restart ZNPP via power lines, despite IAEA safety, cooling, and legal risks.
✅ 80 km high-voltage link toward Mariupol confirmed by imagery
✅ IAEA warns of safety risks and militarization at the site
✅ Cooling capacity limited after Kakhovka dam destruction
Russia is actively constructing new power lines to facilitate the restart of the Zaporizhzhia Nuclear Power Plant (ZNPP), Europe's largest nuclear facility, which it seized from Ukraine in 2022. Satellite imagery analyzed by Greenpeace indicates the construction of approximately 80 kilometers (50 miles) of high-voltage transmission lines and pylons connecting the plant to the Russian-controlled port city of Mariupol. This development marks the first tangible evidence of Russia's plan to reintegrate the plant into its energy infrastructure.
Strategic Importance of Zaporizhzhia Nuclear Power Plant
The ZNPP, located on the eastern bank of the Dnipro River in Enerhodar, was a significant asset in Ukraine's energy sector before its occupation. Prior to the war, the plant was connected to Ukraine's national grid, which later saw resumed electricity exports, via four 750-kilovolt lines, two of which passed through Ukrainian-controlled territory and two through areas under Russian control. The ongoing conflict has damaged these lines, complicating efforts to restore the plant's operations.
In March 2022, Russian forces captured the plant, and by 2023, all six of its reactors had been shut down. Despite this, Russian authorities have expressed intentions to restart the facility. Rosatom, Russia's state nuclear corporation, has identified replacing the power grid as one of the critical steps necessary for resuming operations, even as Ukraine pursues more resilient wind power to bolster its energy mix.
Environmental and Safety Concerns
The construction of new power lines and the potential restart of the ZNPP have raised significant environmental and safety concerns, as the IAEA has warned of nuclear risks from grid attacks in recent assessments. Greenpeace has reported that the plant's cooling system has been compromised due to the destruction of the Kakhovka Reservoir dam in 2023, which previously supplied cooling water to the plant. Currently, the plant relies on wells for cooling, which are insufficient for full-scale operations.
Additionally, the International Atomic Energy Agency (IAEA) has expressed concerns about the militarization of the plant. Reports indicate that Russian forces have established defensive positions and trenches around the facility, with mines found at ZNPP by UN inspectors, raising the risk of accidents and complicating efforts to ensure the plant's safety.
International Reactions and Legal Implications
Ukraine and the international community have condemned Russia's actions as violations of international law and Ukrainian sovereignty. Ukrainian officials have argued that the construction of power lines and the potential restart of the ZNPP constitute illegal activities in occupied territory. The IAEA has called for a ceasefire to allow for necessary safety improvements and to facilitate inspections of the plant, as a possible agreement on power plant attacks could underpin de-escalation efforts.
The United States has also expressed concerns, with President Donald Trump reportedly proposing the inclusion of the ZNPP in peace negotiations, which sparked controversy among Ukrainian and international observers, even suggesting the possibility of transferring control to American companies. However, Russia has rejected such proposals, reaffirming its intention to maintain control over the facility.
The construction of new power lines to the Zaporizhzhia Nuclear Power Plant signifies Russia's commitment to reintegrating the facility into its energy infrastructure. However, this move raises significant environmental, safety, and legal concerns, and a proposal to control Ukraine's nuclear plants remains controversial among stakeholders. The international community continues to monitor the situation closely, urging for adherence to international laws and standards to prevent potential nuclear risks.
Pickering Nuclear False Alert Investigation probes Ontario's emergency alert system after a provincewide cellphone, radio, and TV warning, assessing human error, Pelmorex safeguards, Emergency Management Ontario oversight, and communication delays.
Key Points
An Ontario probe into the erroneous Pickering nuclear alert, focusing on human error, system safeguards, and oversight.
✅ Human error during routine testing suspected
✅ Pelmorex safeguards and EMO protocols under review
✅ Two-hour all-clear delay prompts communication fixes
An investigation into a mistaken Pickering alert warning of an incident at the Pickering Nuclear Generating Station will be completed fairly quickly, Ontario's solicitor general said.
Sylvia Jones tapped the chief of Emergency Management Ontario to investigate how the alert warning of an unspecified problem at the facility was sent in error to cellphones, radios and TVs across the province at about 7:30 a.m. Sunday.
"It's very important for me, for the people of Ontario, to know exactly what happened on Sunday morning," said Jones. "Having said that, I do not anticipate this is going to be a long, drawn-out investigation. I want to know what happened and equally important, I want some recommendations on insurances and changes we can make to the system to make sure it doesn't happen again."
Initial observations suggest human error was responsible for the alert that was sent out during routine tests of the emergency alert, Jones said.
"This has never happened in the history of the tests that they do every day, twice a day, but I do want to know exactly all of the issues related to it, whether it was one human error or whether it was a series of things."
Martin Belanger, the director of public alerting for Pelmorex, a company that operates the alert system, said there are a number of safeguards built in, including having two separate platforms for training and live alerts.
"The software has some steps and some features built in to minimize that risk and to make sure that users will be able to know whether or not they're sending an alert through the...training platform or whether they're accessing the live system in the case of a real emergency," he said.
Only authorized users have access to the system and the province manages that, Belanger said. Once in the live system, features make the user aware of which platform they are using, with various prompts and messages requiring the user's confirmation. There is a final step that also requires the user to confirm their intent of issuing an alert to cellphones, radio and TVs, Belanger said.
On Sunday, a follow-up alert was sent to cellphones nearly two hours after the original notification, and similar grid alerts in Alberta underscore timing and public expectations.
NDP energy critic Peter Tabuns is critical of that delay, noting that ongoing utility scam warnings can further erode public trust.
"That's a long time for people to be waiting to find out what's really going on," he said. "If people lose confidence in this system, the ability to use it when there is a real emergency will be impaired. That's dangerous."
Treasury Board President Peter Bethlenfalvy, who represents the riding of Pickering-Uxbridge, said getting that alert Sunday morning was "a shock to the system," and he too wants the investigation to address the reason for the all-clear delay.
"We all have a lot of questions," he said. "I think the public has every right to know exactly what went on and we feel exactly the same way."
People in the community know the facility is safe, Bethlenfalvy said.
"We have some of the safest nuclear assets in the world -- the safest -- at 60 per cent of Ontario's electricity," he said.
A poll released Monday found that 82 per cent of Canadians are concerned about spills from nuclear reactors contaminating drinking water and 77 per cent are concerned about neighbourhood safety and security risks for those living close to nuclear plants. Oraclepoll Research surveyed 2,094 people across the country on behalf of Friends of the Earth between Jan. 2 and 12, the day of the false alert. The have a margin of error of plus or minus 2.1 per cent, 19 times out of 20.
The wording of Sunday's alert caused much initial confusion, and events like a power outage in London show how morning disruptions can amplify concern, warning residents within 10 kilometres of the plant of "an incident," though there was no "abnormal" release of radioactivity and residents didn't need to take protective steps, but emergency crews were responding.
In the event of a real emergency, the wording would be different, Jones said.
"There are a number of different alerts that are already prepared and are ready to go," she said. "We have the ability to localize it to the communities that are impacted, but because this was a test, it went provincewide."
Jones said she expects the results of the probe to be made public.
The Pickering nuclear plant has been operating since 1971, and had been scheduled to be decommissioned this year, but the former Liberal government -- and the current Progressive Conservative government -- committed to keeping it open until 2024. Decommissioning is now set to start in 2028.
It operates six CANDU reactors, generates 14 per cent of Ontario's electricity and is responsible for 4,500 jobs across the region, according to OPG, and OPG's credit rating remains stable.
During the COVID-19 pandemic, Hydro One employees supported the Province of Ontario in the fight against COVID-19.
The Green party is calling on the province to use this opportunity to review its nuclear emergency response plan, including pandemic staffing contingencies, last updated in 2017 and subject to review every five years.
Toronto Mayor John Tory praised Ontario for swiftly launching an investigation, but said communication between city and provincial officials wasn't what it should have been under the circumstances.
"It was a poor showing and I think everybody involved knows that," he said. "We've got to make sure it's not repeated."
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.
