European Grid Frequency Clock Slowdown has made appliance clocks run minutes behind as AC frequency drifts on the 50 Hz electricity grid, driven by a Kosovo-Serbia billing dispute and ENTSO-E monitored supply-demand imbalance.
Key Points
An EU-wide timing error where 50 Hz AC deviations slow appliance clocks due to Kosovo-Serbia grid imbalances.
✅ Clocks drifted up to six minutes across interconnected Europe
✅ Cause: unpaid power in N. Kosovo, contested by Serbia
✅ ENTSO-E reported 50 Hz deviations from supply-demand mismatch
Over the past couple of months, Europeans have noticed time slipping away from them. It’s not just their imaginations: all across the continent, clocks built into home appliances like ovens, microwaves, and coffee makers have been running up to six minutes slow. The unlikely cause? A dispute between Kosovo and Serbia over who pays the electricity bill.
To make sense of all this, you need to know that the clocks in many household devices use the frequency of electricity to keep time. Electric power is delivered to our homes in the form of an alternating current, where the direction of the flow of electricity switches back and forth many times a second. (How this system came to be established is complex, but the advantage is that it allows electricity to be transmitted efficiently.) In Europe, this frequency is 50 Hertz — meaning a current alternating of 50 times a second. In America, it’s 60 Hz, and during peak summer demand utilities often prepare for blackouts as heat drives loads higher.
Since the 1930s, manufacturers have taken advantage of this feature to keep time. Each clock needs a metronome — something with a consistent rhythm that helps space out each second — and an alternating current provides one, saving the cost of extra components. Customers simply set the time on their oven or microwave once, and the frequency keeps it precise.
At least, that’s the theory. But because this timekeeping method is reliant on electrical frequency, when the frequency changes, so do the clocks. That is what has been happening in Europe.
The news was announced this week by ENTSO-E, the agency that oversees the single, huge electricity grid connecting 25 European countries and which recently synchronized with Ukraine to bolster regional resilience. It said that variations in the frequency of the AC caused by imbalances between supply and demand on the grid have been messing with the clocks. The imbalance is itself caused by a political argument between Serbia and Kosovo. “This is a very sensitive dispute that materializes in the energy issues,” Susanne Nies, a spokesperson for ENTSO-E, told The Verge.
Essentially, after Kosovo declared independence from Serbia in 2008, there were long negotiations over custody of utilities like telecoms and electricity infrastructure. As part of the ongoing agreements (Serbia still does not recognize Kosovo as a sovereign state), four Serb-majority districts in the north of Kosovo stopped paying for electricity. Kosovo initially covered this by charging the rest of the country more, but last December, it decided it had had enough and stopped paying. This led to an imbalance: the Kosovan districts were still using electricity, but no one was paying to put it on the grid.
This might sound weird, but it’s because electricity grids work on a system of supply and demand, where surging consumption has even triggered a Nordic grid blockade in response to constrained flows. As Stewart Larque of the UK’s National Grid explains, you want to keep the same amount of electricity going onto the grid from power stations as the amount being taken off by homes and businesses. “Think of it like driving a car up a hill at a constant speed,” Larque told The Verge. “You need to carefully balance acceleration with gravity.” (The UK itself has not been affected by these variations because it runs its own grid.)
“THEY ARE FREE-RIDING ON THE SYSTEM.”
This balancing act is hugely complex and requires constant monitoring of supply and demand and communication between electricity companies across Europe, and growing cyber risks have spurred a renewed focus on protecting the U.S. power grid among operators worldwide. The dispute between Kosovo and Serbia, though, has put this system out of whack, as the two governments have been refusing to acknowledge what the other is doing.
“The Serbians [in Kosovo] have, according to our sources, not been paying for their electricity. So they are free-riding on the system,” says Nies.
The dispute came to a temporary resolution on Tuesday, when the Kosovan government stepped up to the plate and agreed to pay a fee of €1 million for the electricity used by the Serb-majority municipalities. “It is a temporary decision but as such saves our network functionality,” said Kosovo’s prime minister Ramush Haradinaj. In the longer term, though, a new agreement will need to be reached.
There have been rumors that the increase in demand from northern Kosovo was caused by cryptocurrency miners moving into the area to take advantage of the free electricity. But according to ENTSO-E, this is not the case. “It is absolutely unrelated to cryptocurrency,” Nies told The Verge. “There’s a lot of speculation about this, and it’s absolutely unrelated.” Representatives of Serbia’s power operator, EMS, refused to answer questions on this.
For now, “Kosovo is in balance again,” says Nies. “They are producing enough [electricity] to supply the population. The next step is to take the system back to normal, which will take several weeks.” In other words, time will return to normal for Europeans — if they remember to change their clocks, even as the U.S. power grid sees more blackouts than other developed nations.
Ontario Hydro Disconnection Ban ends May 1, prompting utilities and Hydro One to push payment plans, address arrears, and link low-income assistance, as Sudbury officials urge customers to avoid spring electricity disconnections.
Key Points
A seasonal policy halting winter shutoffs in Ontario, ending May 1 as utilities emphasize payment plans and assistance.
✅ Disconnections resume after winter moratorium ends May 1.
✅ Hydro One delays shutoffs until June 1; arrears down 60%.
The first of May has taken on new meaning this year in Ontario.
It's when the province's ban on hydro disconnections during the winter months comes to an end, even as Ontario considers extending moratoriums in some cases.
Wendy Watson, the director of communications at Greater Sudbury Utilities, says signs of the approaching deadline could be seen in their office of the past few weeks.
"We've had quite an active stream of people into our front office to catch up on their accounts and also we've had a lot of people calling us to make payment arrangements or pay their bill or deal with their arrears," she says.
#google#
Watson says there are 590 customers in Sudbury who could face possible disconnection this spring, compared with just 60 when the ban started in November.
"They will put off until tomorrow what they can avoid today," she says.
Watson says they are hoping to work with customers to figure payment plans with more choice and flexibility and avoid the need to cut power to certain homes and businesses.
"As we like to say we're in the distribution of energy business, not the disconnection of energy business. We want you to be able to turn the lights on," she says.
Joseph Leblanc from the Social Planning Council of Sudbury says the winter hydro disconnection ban is one of several government measures that keep low income families on the brink of disaster. (CBC)
Hydro One executive vice-president of customer care Ferio Pugilese, whose utility later extended disconnection bans across its service area, tells a different story.
He says the company has worked hard to configure payment plans for customers over the last three years amid unchanged peak-rate policies and find ways for them to pay "that fit their lifestyle."
"The threat of a disconnection is not on its own something that's going to motivate someone to pay their bills," says Pugilese.
He says Hydro One is also sending out notices this spring, but won't begin cutting anyone off until June 1st.
He says that disconnections and the amount owing from outstanding bills to Hydro One are down 60 per cent in the last year.
Ontario Energy Minister Glenn Thibeault says there is plenty of help from government programs and utility financing options like Hydro One's relief fund for those having trouble paying their power bills. (CBC)
Sudbury MPP and Energy Minister Glenn Thibeault says his hope is that people having trouble paying their power bills will talk to their hydro utility and look at the numerous programs the government offers to help low-income citizens.
"You know, I really want every customer to have a conversation with their local utility about getting back on track and we do have those programs in place," he says.
However, Joseph Leblanc, the executive director of the Social Planning Council of Sudbury, says the winter disconnection ban is just another government policy that keeps the poor on the brink of disaster.
"It's a feel good story for the government to say that, but it's a band-aid solution. We can stop the bleeding for a little while, make sure people aren't freezing to death in Ontario," he says.
"People choose between rent, hydro, medicine, food, and there's an option for one of those to take some pressure off for a little while."
Instead, Leblanc would like to see the government fast track the province-wide implementation of the basic income program it's testing out in a few cities.
UK Wind and Tidal Power Auction signals strong CfD support for offshore wind, tidal stream projects, investor certainty, and clean electricity, accelerating the net-zero transition, boosting jobs, and strengthening UK energy security and grid integration.
Key Points
A CfD auction awarding contracts for wind and tidal projects to scale clean power and advance UK net-zero.
✅ Jobs, investment, and grid integration accelerate
In a significant development for the UK’s renewable energy sector, the latest auction for renewable energy contracts has underscored a transformative shift towards wind and tidal power. As reported by The Guardian, the auction results reveal a strong commitment to expanding these technologies, with new contracts adding 10 GW to the UK grid, marking a pivotal moment in the UK’s transition to cleaner energy sources.
The Auction’s Impact
The renewable energy auction, which took place recently, has allocated contracts for a substantial increase in wind and tidal power projects. This auction, part of the UK’s Contracts for Difference (CfD) scheme, is designed to support the development of low-carbon energy technologies by providing financial certainty to investors. By offering fixed prices for the electricity generated by these projects, the CfD scheme aims to stimulate investment and accelerate the deployment of renewable energy sources.
The latest results are particularly notable for the significant share of contracts awarded to offshore wind farms and tidal power projects, highlighting how offshore wind is powering up the UK as policy and investment priorities continue to shift. This marks a shift from previous auctions, where solar power and onshore wind were the dominant technologies. The move towards supporting offshore wind and tidal power reflects the UK’s strategic focus on harnessing its abundant natural resources to drive the transition to a low-carbon energy system.
Offshore Wind Power: A Major Contributor
Offshore wind power has emerged as a major player in the UK’s renewable energy landscape, within a global market projected to become a $1 trillion business over the coming decades. The recent auction results highlight the continued growth and investment in this sector.
The UK has been a global leader in offshore wind development, with several large-scale projects already operational and more in the pipeline. The auction has further cemented this position, underscoring what the U.S. can learn from the U.K. in scaling offshore wind capacity, with new projects set to contribute significantly to the country’s renewable energy capacity. These projects are expected to deliver substantial amounts of clean electricity, supporting the UK’s goal of achieving net-zero emissions by 2050.
Tidal Power: An Emerging Frontier
Tidal power, although less developed compared to wind and solar, is gaining momentum as a promising renewable energy source, with companies harnessing oceans and rivers to demonstrate practical potential. The auction results have allocated contracts to several tidal power projects, signaling growing recognition of the potential of this technology.
Tidal power harnesses the energy from tidal movements and currents, which are highly predictable and consistent, and a market outlook for wave and tidal energy points to emerging growth drivers and investment. This makes it a reliable complement to intermittent sources like wind and solar power. The inclusion of tidal power projects in the auction reflects the UK’s commitment to diversifying its renewable energy portfolio and exploring all available options for achieving energy security and sustainability.
Economic and Environmental Benefits
The expansion of wind and tidal power projects through the recent auction offers numerous economic and environmental benefits. From an economic perspective, these projects are expected to create thousands of jobs in construction, maintenance, and manufacturing. They also stimulate investment in local economies and support the growth of the green technology sector.
Environmentally, the increased deployment of wind and tidal power contributes to significant reductions in greenhouse gas emissions. Offshore wind farms and tidal power projects produce clean electricity with minimal environmental impact, helping to mitigate the effects of climate change and improve air quality.
Challenges and Future Outlook
Despite the positive outcomes of the auction, there are challenges to address. Offshore wind farms and tidal power projects require substantial upfront investment and face technical and logistical challenges. Issues such as grid integration, environmental impact assessments, and supply chain constraints need to be carefully managed to ensure the successful deployment of these projects.
Looking ahead, the UK’s renewable energy strategy will continue to evolve as new technologies and innovations emerge, and growth despite Covid-19 underscores sector resilience. The success of the latest auction demonstrates the growing confidence in wind and tidal power and sets the stage for further advancements in renewable energy.
The UK government’s commitment to supporting these technologies through initiatives like the CfD scheme is crucial for achieving long-term energy and climate goals. As the country progresses towards its net-zero target, the continued expansion of wind and tidal power will play a key role in shaping a sustainable and resilient energy future.
Conclusion
The latest renewable energy auction represents a significant milestone in the UK’s transition to a low-carbon energy system. By awarding contracts to wind and tidal power projects, the auction underscores the country’s commitment to harnessing diverse and reliable sources of renewable energy. The expansion of offshore wind and the emerging role of tidal power highlight the UK’s strategic approach to achieving energy security, reducing emissions, and driving economic growth. As the renewable energy sector continues to evolve, the UK remains at the forefront of global efforts to build a sustainable and clean energy future.
ABO Wind Tunisia 10MW Solar Project will build a photovoltaic park in Gabes with a STEG PPA, fixed tariff, 2,500 m grid connection, producing 18 million kWh annually, targeted for 2020 commissioning with local partners.
Key Points
A 10MW photovoltaic park in Gabes with a 20-year STEG PPA and fixed tariff, slated for 2020 commissioning.
✅ 18 million kWh/year; 2,500 m grid tie, 20-year fixed tariff
✅ Electricity supplied to STEG under PPA; 2020 commissioning
✅ Located in Gabes; built with local partners, 10MW capacity
ABO Wind has received a permit and a tariff for a 10MW photovoltaic project in Tunisia, amid global activity such as Spain's 90MW wind project now underway, which it plans to build and commission in 2020.
The solar park, in the governorate of Gabes, is 400km south of the country’s capital Tunis and aligns with renewable funding initiatives seen across developing markets.
The developer said it plans to build the project next year in close cooperation with local partners, as regional markets from North Africa to the Gulf expand, with Saudi Arabia boosting wind capacity as well.
ABO Wind department head Nicolas Konig said: “The solar park will produce more than 18 million kilowatt hours of electricity per year and will feed it into the grid at a distance of 2500 metres.”
The developer will conclude an electricity supply contract with the state-owned energy supplier (Societe tunisienne de l’electricite et du gaz (STEG), which will provide a fixed remuneration over 20 years, a model echoed by Germany's wind-solar tender for the electricity fed into the grid.
Earlier this year, ABO Wind had already secured a tariff for a wind farm with a capacity of 30MW in a tender, 35km south-east of Tunis, underscoring Tunisia's wind investments under its long-term plan.
The company is working on half a dozen Tunisian wind and solar projects, as institutions like the World Bank support wind growth in developing countries.
“We are making good progress on our way to assemble a portfolio of several ready-to-build wind and solar projects attractive to investors, as Saudi clean energy targets continue to expand globally,” said ABO Wind general manager responsible for international business development Patrik Fischer.
Western Canada Electric Grid could deliver interprovincial transmission, reliability, peak-load support, reserve sharing, and wind and solar integration, lowering costs versus new generation while respecting AESO markets and Crown utility structures.
Key Points
Interprovincial transmission to share reserves, boost reliability, integrate wind and solar, and cut peak capacity costs.
✅ Cuts reserve margins via diversity of peak loads
✅ Enables wind and solar balancing across provinces
✅ Saves ratepayers vs replacing retiring thermal plants
The 2017 Canadian Free Trade Agreement does not do much to encourage provinces to trade electric energy east and west. Would a western Canada electric grid help electricity consumers in the western provinces? Some Alberta officials feel that their electric utilities are investor owned and they perceive the Crown corporations of BC Hydro, SaskPower and Manitoba Hydro to be subsidized by their provincial governments, so an interprovincial electric energy trade would not be on a level playing field.
Because of the limited trade of electric energy between the western provinces, each utility maintains an excessive reserve of thermal and hydroelectric generation greater than their peak loads, to provide a reliable supply during peak load days as grids are increasingly exposed to harsh weather across Canada. This excess does not include variable wind and solar generation, which within a province can’t be guaranteed to be available when needed most.
This attitude must change. Transmission is cheaper than generation, and coordinated macrogrids can further improve reliability and cut costs. By constructing a substantial grid with low profile and aesthetically designed overhead transmission lines, the excess reserve of thermal and hydroelectric generation above the peak electric load can be reduced in each province over time. Detailed assessments will ensure each province retains its required reliability of electric supply.
As the provinces retire aging thermal and coal-fired generators, they only need to replace them to a much lower level, by just enough to meet their future electric loads and Canada's net-zero grid by 2050 goals. Some of the money not spent in replacing retired generation can be profitably invested in the transmission grid across the four western provinces.
But what about Alberta, which does not want to trade electric energy with the other western provinces? It can carry on as usual within the Alberta Electric System Operator’s (AESO) market and will save money by keeping the installed reserve of thermal and hydroelectric generation to a minimum. When Alberta experiences a peak electric load day and some generators are out of service due to unplanned maintenance, it can obtain the needed power from the interprovincial electric grid. None of the other three western provinces will peak at the same time, because of different weather and time zones, so they will have spare capacity to help Alberta over its peak. The peak load in a province only lasts for a few hours, so Alberta will get by with a little help from its friends if needed.
The grid will have no energy flowing on it for this purpose except to assist a province from time to time when it’s unable to meet its peak load. The grid may only carry load five per cent of the time in a year for this purpose. Under such circumstances, the empty grid can then be used for other profitable markets in electric energy. This includes more effective use of variable wind and solar energy, by enabling a province to better balance such intermittent power as well as allowing increased installation of it in every province. This is a challenge for AESO which the grid would substantially ease.
Natural Resources Canada promoted the “Regional Electricity Co-Operative and Strategic Infrastructure” initiative for completion this year and contracted through AESO, alongside an Atlantic grid study to explore regional improvements. This is a first step, but more is needed to achieve the full benefit of a western grid.
In 1970 a study was undertaken to electrically interconnect Britain with France, which was justified based on the ability to reduce reserve generation in both countries. Initially Britain rejected it, but France was partially supportive. In time, a substantial interconnection was built, and being a profitable venture, they are contemplating increasing the grid connections between them.
For the sake of the western consumers of electricity and to keep electricity rates from rising too quickly, as well as allowing productive expansion of wind and solar energy in places like British Columbia's clean energy shift efforts, an electric grid is essential across western Canada.
Dennis Woodford is president of Electranix Corporation in Winnipeg, which studies electric transmission problems, particularly involving renewable energy generators requiring firm connection to the grid.
Tesla Energy Ventures Texas enters the deregulated market as a retail electricity provider, leveraging ERCOT, battery storage, solar, and grid software to enable virtual power plants and customer energy trading with Powerwall and Megapack assets.
Key Points
Tesla Energy Ventures Texas is Tesla's retail power unit selling grid and battery energy and enabling solar exports.
✅ ERCOT retail provider; sells grid and battery-stored power
✅ Uses Powerwall/Megapack; supports virtual power plants
✅ Targets Tesla owners; enables solar export and trading
Last week, Tesla Energy Ventures, a new subsidiary of electric car maker Tesla Inc. (TSLA), filed an application to become a retail electricity provider in the state of Texas. According to reports, the company plans to sell electricity drawn from the grid to customers and from its battery storage products. Its grid transaction software may also enable customers for its solar panels to sell excess electricity back to the smart grid in Texas.1
For those who have been following Tesla's fortunes in the electric car industry, the Palo Alto, California-based company's filing may seem baffling. But the move dovetails with Tesla's overall ambitions for its renewable energy business, as utilities face federal scrutiny of climate goals and electricity rates.
Why Does Tesla Want to Become an Electricity Provider? The simple answer to that question is that Tesla already manufactures devices that produce and store power. Examples of such devices are its electric cars, which come equipped with lithium ion batteries, and its suite of battery storage products for homes and enterprises. Selling power generated from these devices to consumers or to the grid is a logical next step.
Tesla's move will benefit its operations. The filing states that it plans to build a massive battery storage plant near its manufacturing facility in Austin. The plant will provide the company with a ready and cheap source of power to make its cars.
Tesla's filing should also be analyzed in the context of the Texas grid. The state's electricity market is fully deregulated, unlike regions debating grid privatization approaches, and generated about a quarter of its overall power from wind and solar in 2020.2 The Biden administration's aggressive push toward clean energy is only expected to increase that share.
After a February fiasco in the state grid resulted in a shutdown of renewable energy sources and skyrocketing natural gas prices, Texas committed to boosting the role of battery storage in its grid. The Electricity Reliability Council of Texas (ERCOT), the state's grid operator, has said it plans to install 3,008 MW of battery storage by the end of 2022, a steep increase from the 225 MW generated at the end of 2020.3 ERCOT's proposed increase in installation represents a massive market for Tesla's battery unit.
Tesla already has considerable experience in this arena. It has built battery storage plants in California and Australia and is building a massive battery storage unit in Houston, according to a June Bloomberg report.4 The unit is expected to service wholesale power producers. Besides this, the company plans to "drum up" business among existing customers for its batteries through an app and a website that will allow them to buy and sell power among themselves, a model also being explored by Octopus Energy in international talks.
Tesla Energy Ventures: A Future Profit Center? Tesla's foray into becoming a retail electricity provider could boost the top line for its energy services business, even as issues like power theft in India highlight retail market challenges. In its last reported quarter, the company stated that its energy generation and storage business brought in $810 million in revenues.
Analysts have forecast a positive future for its battery storage business. Alex Potter from research firm Piper Sandler wrote last year that battery storage could bring in more than $200 billion per year in revenue and grow up to a third of the company's overall business.5
Immediately after the news was released, Morningstar analyst Travis Miller wrote that Tesla does not represent an immediate threat to other major players in Texas's retail market, where providers face strict notice obligations illustrated when NT Power was penalized for delayed disconnection notices, such as NRG Energy, Inc. (NRG) and Vistra Corp. (VST). According to him, the company will initially target its own customers to "complement" its offerings in electric cars, battery, charging, and solar panels.6
Further down the line, however, Tesla's brand name and resources may work to its advantage. "Tesla's brand name recognition gives it an advantage in a hypercompetitive market," Miller wrote, adding that the car company's entry confirmed the firm's view that consumer technology or telecom companies will try to enter retail energy markets, where policy shifts like Ontario rate reductions can shape customer expectations.
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.
