An Anchorage utility wants a federal appeals court to block exports of Cook Inlet natural gas to Asia.
Chugach Electric Association generates much of the power it sells by burning natural gas.
The utility's petition — with the San Francisco-based 9th U.S. Circuit Court of Appeals — challenges a U.S. Department of Energy decision.
The June decision would allow oil companies, ConocoPhillips and Marathon, to keep exporting Cook Inlet gas through March 2011.
Chugach's Sept. 26 petition is the latest sign of rising local energy tensions in southcentral Alaska, where natural gas is a critical commodity for heating and powering homes and businesses.
Cook Inlet gas fields once held far more gas than needed for local needs.
But gas reserves have begun to dwindle. Signs of tightening supply have shown up in the form of higher retail gas prices as well as the closure of a gas-dependent fertilizer plant in Nikiski.
"Chugach is the largest electric utility in the state of Alaska," Suzanne Gibson, the utility's energy resources director, said in a statement. "We have an obligation and duty to protect our customers by ensuring that there is adequate natural gas in Cook Inlet and that it is available at a reasonable price. That is why we are involved in this case."
Conoco and minority partner Marathon have been exporting liquefied natural gas, or LNG, from the Kenai Peninsula since 1967. The gas is cooled into a liquid and loaded onto tankers bound for utility customers in Japan.
Historically the process accounts for more than a third of total consumption of Cook Inlet gas.
The DOE's Office of Fossil Energy authorized LNG exports for two more years beginning in April, judging Cook Inlet gas as sufficient to meet both local and export demand.
Chugach's request for a rehearing of the DOE order was denied.
Robert Corbin, a DOE official who signed the export order, said he has been advised by government attorneys not to comment on the Chugach court challenge.
A Conoco spokeswoman, Natalie Lowman, also declined comment.
Gov. Sarah Palin and other export supporters said continued overseas gas shipments could encourage Conoco and others to drill for new gas supplies.
But the Regulatory Commission of Alaska recently raised concern about the DOE decision.
The five-member commission said in an October order that the DOE as well as state officials "could have done a better job in ensuring that local needs were met at reasonable pricing terms before the LNG export license was extended."
The panel at the time was considering two wholesale gas supply contracts for Enstar Natural Gas Co.
UK Hydrogen Storage Caverns enable long-duration, low-carbon electricity balancing, storing surplus wind and solar power as green hydrogen in salt formations to enhance grid reliability, energy security, and net zero resilience by 2035 and 2050.
Key Points
They are salt caverns storing green hydrogen to balance wind and solar, stabilizing a low-carbon UK grid.
✅ Stores surplus wind and solar as green hydrogen in salt caverns
✅ Enables long-duration, low-carbon grid balancing and security
✅ Complements wind and solar; reduces dependence on flexible CCS
The U.K. government must kick-start the construction of large-scale hydrogen storage facilities if it is to meet its pledge that all electricity will come from low-carbon electricity sources by 2035 and reach legally binding net zero targets by 2050, according to a report by the Royal Society.
The report, "Large-scale electricity storage," published Sep. 8, examines a wide variety of ways to store surplus wind and solar generated electricity—including green hydrogen, advanced compressed air energy storage (ACAES), ammonia, and heat—which will be needed when Great Britain's electricity generation is dominated by volatile wind and solar power.
It concludes that large scale electricity storage is essential to mitigate variations in wind and sunshine, particularly long-term variations in the wind, and to keep the nation's lights on. Storing most of the surplus as hydrogen, in salt caverns, would be the cheapest way of doing this.
The report, based on 37 years of weather data, finds that in 2050 up to 100 Terawatt-hours (TWh) of storage will be needed, which would have to be capable of meeting around a quarter of the U.K.'s current annual electricity demand. This would be equivalent to more than 5,000 Dinorwig pumped hydroelectric dams. Storage on this scale, which would require up to 90 clusters of 10 caverns, is not possible with batteries or pumped hydro.
Storage requirements on this scale are not currently foreseen by the government, and the U.K.'s energy transition faces supply delays. Work on constructing these caverns should begin immediately if the government is to have any chance of meeting its net zero targets, the report states.
Sir Chris Llewellyn Smith FRS, lead author of the report, said, "The need for long-term storage has been seriously underestimated. Demand for electricity is expected to double by 2050 with the electrification of heat, transport, and industrial processing, as well as increases in the use of air conditioning, economic growth, and changes in population.
"It will mainly be met by wind and solar generation. They are the cheapest forms of low-carbon electricity generation, but are volatile—wind varies on a decadal timescale, so will have to be complemented by large scale supply from energy storage or other sources."
The only other large-scale low-carbon sources are nuclear power, gas with carbon capture and storage (CCS), and bioenergy without or with CCS (BECCS). While nuclear and gas with CCS are expected to play a role, they are expensive, especially if operated flexibly.
Sir Peter Bruce, vice president of the Royal Society, said, "Ensuring our future electricity supply remains reliable and resilient will be crucial for our future prosperity and well-being. An electricity system with significant wind and solar generation is likely to offer the lowest cost electricity but it is essential to have large-scale energy stores that can be accessed quickly to ensure Great Britain's energy security and sovereignty."
Combining hydrogen with ACAES, or other forms of storage that are more efficient than hydrogen, could lower the average cost of electricity overall, and would lower the required level of wind power and solar supply.
There are currently three hydrogen storage caverns in the U.K., which have been in use since 1972, and the British Geological Survey has identified the geology for ample storage capacity in Cheshire, Wessex and East Yorkshire. Appropriate, novel business models and market structures will be needed to encourage construction of the large number of additional caverns that will be needed, the report says.
Sir Chris observes that, although nuclear, hydro and other sources are likely to play a role, Britain could in principle be powered solely by wind power and solar, supported by hydrogen, and some small-scale storage provided, for example, by batteries, that can respond rapidly and to stabilize the grid. While the cost of electricity would be higher than in the last decade, we anticipate it would be much lower than in 2022, he adds.
25% Tariff on Canadian Imports threatens New York energy markets, disrupting hydroelectric power and natural gas supply chains, raising electricity prices, increasing gas costs, and intensifying trade tensions, policy uncertainty, and cross-border logistics risks.
Key Points
A U.S. policy imposing 25% duties on Canadian goods, risking higher New York electricity and natural gas costs.
✅ Hydroelectric and gas imports face costlier cross-border flows
✅ Higher utility bills for NY households and businesses
✅ Supply chain volatility and policy uncertainty increase
President Donald Trump announced the imposition of a 25% tariff on all imports from Canada, citing concerns over drug trafficking and illegal immigration. This decision has raised significant concerns among experts and residents in New York, who warn that the tariff could lead to increased electricity and gas prices in the state.
Impact on New York's Energy Sector
New York relies heavily on energy imports from Canada, particularly electricity and natural gas. Canada is a major supplier of hydroelectric power to the northeastern United States, including New York, with its electricity exports at risk amid trade tensions. The imposition of a 25% tariff on Canadian goods could disrupt this supply chain, leading to higher energy costs for consumers and businesses in New York. Justin Wilcox, an energy analyst, stated, "If the tariff is implemented, it could lead to increased costs for electricity and gas, affecting both consumers and businesses."
Potential Economic Consequences
The increased energy costs could have broader economic implications for New York, and some experts advise against cutting Quebec's exports to avoid exacerbating market volatility. Higher electricity and gas prices may lead to increased operational costs for businesses, potentially resulting in higher prices for goods and services, while tariff threats have boosted support for Canadian energy projects that could reshape regional supply. This could exacerbate the cost-of-living challenges faced by residents and strain the state's economy.
Political and Diplomatic Reactions
The tariff has also sparked political and diplomatic reactions, including threats to cut U.S. electricity exports from Ontario that raised tensions. New York Governor Kathy Hochul expressed concern over the potential economic impact, stating, "We are closely monitoring the situation and are prepared to take necessary actions to protect New York's economy." Additionally, Canadian officials have expressed their disapproval of the tariff, and Ontario Premier Doug Ford's Washington meeting underscored ongoing discussions, emphasizing the importance of the trade relationship between the two countries.
Historical Context
This development is part of a broader pattern of trade tensions between the United States and its neighbors. In 2018, the U.S. imposed tariffs on Canadian steel and aluminum, leading to retaliatory measures from Canada. The current situation underscores the ongoing challenges in international trade relations, where a recent tariff threat delayed Quebec's green energy bill and highlighted the potential domestic impacts of such policies.
The imposition of a 25% tariff on Canadian imports by President Trump has raised significant concerns in New York regarding potential increases in electricity and gas prices. Experts warn that this could lead to higher costs for consumers and businesses, with broader economic implications for the state. As the situation develops, it will be crucial to monitor the responses from both state and federal officials, as well as how Canadians support tariffs on energy and minerals may influence policy, and the potential for diplomatic negotiations to address these trade tensions.
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.
Ontario Teachers SSEN Transmission Investment advances UK renewable energy, with a 25% minority stake in SSE plc's electricity transmission network, backing offshore wind, grid expansion, and Net Zero 2050 goals across Scotland and UK.
Key Points
A 25% stake by Ontario Teachers in SSE's SSEN Transmission to fund UK grid upgrades and accelerate renewables.
✅ £1,465m cash for 25% minority stake in SSEN Transmission
✅ Supports offshore wind, grid expansion, and Net Zero targets
✅ Partnering SSE plc to deliver clean, affordable power in the UK
Ontario Teachers’ Pension Plan Board (‘Ontario Teachers’) has reached an agreement with Scotland-based energy provider SSE plc (‘SSE’) to acquire a 25% minority stake in its electricity transmission network business, SSEN Transmission, to provide clean, affordable renewable energy to millions of homes and businesses across the UK, reflecting how clean-energy generation powers both the economy and the environment.
The transaction is based on an effective economic date of 31 March 2022, and total cash proceeds of £1,465m for the 25% stake are expected at completion. The transaction is expected to complete shortly.
Measures such as Ontario's 2021 electricity rate reductions have aimed to ease costs for businesses, informing broader discussions on affordability.
SSEN Transmission, which operates under its licenced entity, Scottish Hydro Electric Transmission plc, transports electricity generated from renewable resources – including onshore and offshore wind and hydro – from the north of Scotland across more than a quarter of the UK land mass amid scrutiny of UK electricity and gas networks profits under the regulatory regime. The investment by Ontario Teachers’ will help support the UK Government’s Net Zero 2050 targets, including the delivery of 50GW of offshore wind capacity by 2030.
Charles Thomazi, Senior Managing Director, Head of EMEA Infrastructure & Natural Resources, from Ontario Teachers’ said, noting that in Canada decisions like the OEB decision on Hydro One's T&D rates guide utility planning:
“SSEN Transmission is one of Europe’s fastest growing transmission networks. Its network stretches across some of the most challenging terrain in Scotland – from the North Sea and across the Highlands – to deliver safe, reliable, renewable energy to demand centres across the UK.
We’re delighted to partner again with SSE and are committed to supporting the growth of its network and the vital role it plays in the UK’s green energy revolution.”
Investor views on regulated utilities can diverge, as illustrated by analyses of Hydro One's investment outlook that weigh uncertainties and risk factors.
Rob McDonald, Managing Director of SSEN Transmission, said:
“With the north of Scotland home to the UK’s greatest resources of renewable electricity we have a critical role to play in helping deliver the UK and Scottish Governments net zero commitments. Our investments will also be key to securing the UK’s future energy independence through enabling the deployment of homegrown, affordable, low carbon power.
“With significant growth forecast in transmission, bringing in Ontario Teachers’ as a minority stake partner will help fund our ambitious investment plans as we continue to deliver a network for net zero emissions across the north of Scotland.”
Ontario Teachers’ Infrastructure & Natural Resources group invests in electricity infrastructure worldwide to accelerate the energy transition with current investments including Caruna, Finland’s largest electricity distributor, Evoltz, a leading electricity transmission platform in Brazil, and Spark Infrastructure, which invests in essential energy infrastructure in Australia to serve over 5 million homes and businesses.
In Ontario, distribution consolidation has included the sale of Peterborough Distribution to Hydro One for $105 million, illustrating ongoing sector realignment.
Sudbury Electrification and Grid Expansion is driving record power demand, EV charging, renewable energy planning, IESO forecasts, smart grid upgrades, battery storage, and industrial electrification, requiring cleaner power plants and transmission capacity in northern Ontario.
Key Points
Rising electricity demand and clean energy upgrades in Sudbury to power EVs, industry, and a smarter, expanded grid.
✅ IESO projects system size may need to more than double
✅ EVs and smart devices increase peak and off-peak load
✅ Battery storage and V2G can support reliability and resiliency
Sudbury, Ont., is consuming more power than ever, amid an electricity supply crunch in Ontario, according to green energy organizations that say meeting the demand will require cleaner energy sources.
"This is the welfare of the entire city on the line and they are putting their trust in electrification," said David St. Georges, manager of communications at reThink Green, a non-profit organization focused on sustainability in Sudbury.
According to St. Georges, Sudbury and northern Ontario can meet the growing demand for electricity to charge clean power for EVs and smart devices.
According to the Independent Electricity System Operator (IESO), making a full switch from fossil fuels to other renewable energy sources could require more power plants, while other provinces face electricity shortages of their own.
"We have forecasted that Ontario's electricity system will need significant expansion to meet this, potentially more than doubling in size," the IESO told CBC News in an emailed statement.
Electrification in the industrial sector is adding greater demand to the electrical grid as electric cars challenge power grids in many regions. Algoma Steel in Sault Ste. Marie and ArcelorMittal Dofasco in Hamilton both aim to get electric arc furnaces in operation. Together, those projects will require 630 megawatts.
"That's like adding four cities the size of Sudbury to the grid," IESO said.
Devin Arthur, chapter president of the Electric Vehicle society in Greater Sudbury, said the city is coming full circle with fully electrifying its power grid, reflecting how EVs are a hot topic in Alberta and beyond.
"We're going to need more power," he said.
"Once natural gas was introduced, that kind of switched back, and everyone was getting out of electrification and going into natural gas and other sources of power."
Despite Sudbury's increased appetite for electricity, Arthur added it's also easier to store now as Ontario moves to rely on battery storage solutions.
"What that means is you can actually use your electric vehicle as a battery storage device for the grid, so you can actually sell power from your vehicle that you've stored back to the grid, if they need that power," he said.
Harneet Panesar, chief operating officer for the Ontario Energy Board, told CBC the biggest challenge to going green is seeing if it can work around older infrastructure, while policy debates such as Canada's 2035 EV sales mandate shape the pace of change.
"You want to make sure that you're building in the right spot," he said.
"Consumers are shifting from combustion engines to EV drivetrains. You're also creating more dependency. At a very high level, I'm going to say it's probably going to go up in terms of the demand for electricity."
Fossil fuels are the first to go for generating electricity, said St. Georges.
"But we're not there yet, because it's not a light switch solution. It takes time to get to that, which is another issue of electrification," he said.
"It's almost impossible for us not to go that direction."
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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