Foote Creek I Wind Farm Repowering upgrades Wyoming turbines with new nacelles, towers, and blades, cutting 68 units to 12 while sustaining 41.6 MW, under PacifiCorp and Rocky Mountain Power's Energy Vision 2020 plan.
Key Points
Replacement at Foote Creek Rim I, cutting to 12 turbines while sustaining about 41.6 MW using modern 2-4.2 MW units.
✅ 12 turbines replace 68, output steady near 41.6 MW
✅ New nacelles, towers, blades; taller 500 ft turbines
✅ Part of PacifiCorp Energy Vision 2020 and Gateway West
A Wyoming utility company has filed a permit to replace its first wind farm—originally commissioned in 1998, composed of over 65 turbines—amid new gas capacity competing with nuclear in Ohio, located at Foote Creek Rim I. The replacement would downsize the number of turbines to 12, which would still generate roughly the same energy output.
According to the Star Tribune, PacifiCorp’s new installation would involve new nacelles, new towers and new blades. The permit was filed with Carbon County.
New WY Wind Farm
The replacement wind turbines will stand more than twice as tall as the old: Those currently installed stand 200 feet tall, whereas their replacements will tower closer to 500 feet. Though this move is part of the company’s overall plan to expand its state wind fleet as some utilities respond to declining coal returns in the Midwest, the work going into the Foote Creek site is somewhat special, noted David Eskelsen, spokesperson for Rocky Mountain Power, the western arm of PacifiCorp.
“Foote Creek I repowering is somewhat different from the repowering projects announced in the (Energy Vision) 2020 initiative,” he said. “Foote Creek is a complete replacement of the existing 68 foundations, towers, turbine nacelles and rotors (blades).”
Currently, the turbines at Foote Creek have 600 kilowatts capacity each; the replacements’ maximum production ranges from 2 megawatts to 4.2 megawatts each, with the total output remaining steady at 41.4 megawatts, a scale similar to a 30-megawatt wind expansion in Eastern Kings, though there will be a slight capacity increase to 41.6 megawatts, according to the Star Tribune.
As part of the wind farm repowering initiative, PacifiCorp is to become full owner and operator of the Foote Creek site. When the farm was originally built, an Oregon-based water and electric board was 21 percent owner; 37 percent of the project’s output was tied into a contract with the Bonneville Power Administration.
Otherwise, PacifiCorp is moving to further expand its state wind fleet in line with initiatives like doubling renewable electricity by 2030 in Saskatchewan, with the addition of three new wind farms—to be located in Carbon, Albany and Converse counties—which may add up to 1,150 megawatts of power.
According to PacifiCorp, the company has more than 1,000 megawatts of owned wind generation capability, along with long-term purchase agreements for more than 600 megawatts from other wind farms owned by other entities. Energy Vision 2020 refers to a $3.5 billion investment and company move that is looking to upgrade the company's existing wind fleet with newer technology, adding 1,150 megawatts of new wind resources by 2020 and a a new 140-mile Gateway West transmission segment in Wyoming, comparable to a transmission project in Missouri just energized.
AWS Renewable Energy Projects deliver new wind power for AWS data centers in Ireland, Sweden, and the US, adding 229 MW and 670,000 MWh annually, supporting 100% renewable targets and global cloud sustainability.
Key Points
AWS projects add wind power in Ireland, Sweden, and the US to supply clean energy for AWS data centers.
✅ 229 MW new wind capacity; 670,000 MWh annual generation
✅ Advances 100% renewable goal for global AWS infrastructure
Amazon has announced three new clean energy projects as part of its long-term goal to power all Amazon Web Services (AWS) global infrastructure with renewable energy. These projects – one in Ireland, one in Sweden, and one in the United States – will deliver wind-generated energy that will total over 229 megawatts (MW) of power, with expected generation of over 670,000 megawatt hours (MWh) of renewable energy annually. The new projects are part of AWS’s long-term commitment to achieve 100 percent renewable energy for its global infrastructure. In 2018, AWS exceeded 50 percent renewable energy for its global infrastructure.
Once complete, these projects, combined with AWS’s previous nine renewable energy projects, reflect how renewable power developers benefit from diversified sources and are expected to generate more than 2,700,000 MWh of renewable energy annually – equivalent to the annual electricity consumption of over 262,000 US homes, which is approximately the size of the city of Nashville, Tennessee.
“Each of these projects brings us closer to our long-term commitment to use 100 percent renewable energy to power our global AWS infrastructure,” said Peter DeSantis, Vice President of Global Infrastructure and Customer Support, Amazon Web Services. “These projects are well-positioned to serve AWS data centers in Ireland, Sweden, and the US. We expect more projects in 2019 as we continue toward our goal of powering all AWS global infrastructure with renewable energy.”
Amazon has committed to buying the energy from a new wind project in Ireland, a 91.2 MW wind farm in Donegal. The Donegal wind farm project is expected to deliver clean energy no later than the end of 2021.
“AWS’s investment in renewable projects in Ireland illustrates their continued commitment to adding clean energy to the grid and it will make a positive contribution to Ireland’s renewable energy goals,” said Leo Varadkar, An Taoiseach of Ireland. “As a significant employer in Ireland, it is very encouraging to see Amazon taking a lead on this issue. We look forward to continuing to work with Amazon as we strive to make Ireland a leader on renewable energy.”
Amazon will also purchase 91 MW of power from a new wind farm in Bäckhammar, Sweden, which is expected to deliver renewable energy by the end of 2020.
“Sweden has long been known for ambitious renewable energy goals, and this new wind farm showcases both our country’s leadership and AWS’s commitment to renewable energy,” said Anders Ygeman, Sweden’s Minister for Energy and Digital Development. “This is a significant step in Sweden’s renewable energy production as we work toward our target of 100 percent renewable energy by 2040.”
California leads the United States in renewable electricity generation from non-hydroelectric sources, as US solar and wind growth accelerates, and the state’s Tehachapi Mountains, where AWS’s wind farm will be located, contain some of the largest wind farms in the country. The wind farm project in Tehachapi is expected to bring up to 47 MW of new renewable energy capacity by the end of 2020.
“This announcement from AWS is great news, not just for California, but for the entire country, as it reaffirms our role as a leader in renewable energy and allows us to take an important step forward on deploying the clean energy we need to respond to climate change,” said California State Senator Jerry Hill, San Mateo and Santa Clara Counties, a member of the Senate Standing Committee on Energy, Utilities and Communications.
Beyond the sustainability initiatives focused on powering the AWS global infrastructure, Amazon recently announced Shipment Zero, which is Amazon’s vision to make all Amazon shipments net zero carbon, with 50 percent of all shipments net zero by 2030. Additional sustainability programs across the company include Amazon Wind Farm Texas, which adds more than 1 million MWh of clean energy each year, alongside Amazon Wind Farm US East that is now fully operational, demonstrating scale. In total, Amazon has enabled 53 wind and solar projects worldwide, which produce more than 1,016 MW and are expected to deliver over 3,075,636 million MWh of energy annually, while peers like Arvato's solar power plant underscore broader momentum across the industry. These projects support hundreds of jobs, while providing tens of millions of dollars of investment in local communities, with Iowa wind power offering a strong example. Amazon has also set a goal to host solar energy systems at 50 fulfillment centers by 2020. This deployment of rooftop solar systems, aided by cheap batteries that enhance storage, is part of a long-term initiative that will start in North America and spread across the globe. Amazon also implemented the District Energy Project that uses recycled energy for heating Amazon offices in Seattle. For more information on Amazon’s sustainability initiatives, visit www.amazon.com/sustainability.
Ukraine Electricity Imports surge to record levels as EU neighbors bolster grid stability amid Russian strikes, supporting energy security, preventing blackouts, and straining cross-border transmission capacity while Ukraine rebuilds damaged infrastructure and diversifies with renewables.
Key Points
Emergency EU power purchases stabilizing Ukraine’s grid after war damage.
✅ Record 19,000 MWh per day from EU interconnectors
✅ Supports grid stability and blackout prevention
✅ Cost and transmission upgrades challenge sustainability
Russia's ongoing war in Ukraine has extended far beyond the battlefield, with critical infrastructure becoming a target. Ukraine's once-robust energy system has sustained significant damage amid energy ceasefire violations and Russian missile and drone strikes. To cope with these disruptions and maintain power supplies for Ukrainian citizens, the country is turning to record-breaking electricity imports from neighboring European nations.
Prior to the war, Ukraine enjoyed a self-sufficient energy sector, even exporting electricity to neighboring countries. However, targeted attacks on power plants and transmission lines have crippled generation capacity. The situation is particularly dire in eastern and southern Ukraine, where ongoing fighting has caused extensive damage.
Faced with this energy crisis, Ukraine is looking to Europe for a lifeline. The country's energy ministry has announced plans to import a staggering amount of electricity – exceeding 19,000 megawatt-hours (MWh) per day – to prepare for winter and stabilize supplies. This surpasses the previous record set in March 2024 and represents a significant increase in Ukraine's reliance on external power sources.
Several European nations are stepping up to support Ukraine. Countries like Poland, Slovakia, Romania, Hungary, which maintains quiet energy ties with Russia today, and Moldova have agreed to provide emergency electricity supplies. These imports will help stabilize Ukraine's power grid and prevent widespread blackouts, especially during peak consumption hours.
The reliance on imports, however, presents its own set of challenges. Firstly, the sheer volume of electricity needed puts a strain on the capacity of neighboring grids. Upgrading and expanding transmission infrastructure will be crucial to ensure a smooth flow of electricity. Secondly, the cost of imported electricity can be higher than domestically generated power amid price hikes and instability globally, placing additional pressure on Ukraine's already strained finances.
Beyond these immediate concerns, the long-term implications of relying on external energy sources need to be considered. Ukraine's long-term goal is to rebuild its own energy infrastructure and regain energy independence. International assistance, including energy security support measures, will be crucial in this endeavor. Financial aid and technical expertise can help Ukraine repair damaged power plants, diversify its energy mix through further investment in renewables, and develop more resilient grid infrastructure.
The war in Ukraine has underscored the importance of energy security. A nation's dependence on a single source of energy, be it domestic or foreign, leaves it vulnerable to disruption, as others consider national security and fossil fuels in their own policies. For Ukraine, diversification and building a more resilient energy infrastructure are key takeaways from this crisis.
The international community also has a role to play. Supporting Ukraine's energy sector not only helps the nation weather the current crisis but also strengthens European energy security as a whole, where concerns over Europe's energy nightmare remain pronounced. A stable and independent Ukraine, less reliant on Russian energy, contributes to a more secure and prosperous Europe.
As the war in Ukraine continues, the battle for energy security rages on. While the immediate focus is on keeping the lights on through imports, the long-term goal for Ukraine is to rebuild a stronger, more resilient energy sector that can power the nation's future. The international community's support will be crucial in helping Ukraine achieve this goal.
Global Decarbonization Strategies align renewable energy, electrification, clean air policies, IMO sulfur cap, LNG fuels, and the EU 2050 roadmap to cut carbon intensity and meet Paris Agreement targets via EVs and efficiency.
Key Points
Frameworks that cut emissions via renewables, EVs, efficiency, cleaner marine fuels, and EU policy roadmaps.
✅ Renewables scale as wind and solar outcompete new coal and gas.
✅ Electrification of transport grows as EV costs fall and charging expands.
✅ IMO 2020 sulfur cap and LNG shift cut shipping emissions and particulates.
Are we doing enough to save the planet? Silly question. The latest prognosis from the United Nations’ Intergovernmental Panel on Climate Change made for gloomy reading. Fundamental to the Paris Agreement is the target of keeping global average temperatures from rising beyond 2°C. The UN argues that radical measures are needed, and investment incentives for clean electricity are seen as critical by many leaders to accelerate progress to meet that target.
Renewable power and electrification of transport are the pillars of decarbonization. It’s well underway in renewables - the collapse in costs make wind and solar generation competitive with new build coal and gas.
Renewables’ share of the global power market will triple by 2040 from its current level of 6% according to our forecasts.
The consumption side is slower, awaiting technological breakthrough and informed by efforts in countries such as New Zealand’s electricity transition to replace fossil fuels with electricity. The lower battery costs needed for electric vehicles (EVs) to compete head on and displace internal combustion engine (ICE) cars are some years away. These forces only start to have a significant impact on global carbon intensity in the 2030s. Our forecasts fall well short of the 2°C target, as does the IEA’s base case scenario.
Yet we can’t just wait for new technology to come to the rescue. There are encouraging signs that society sees the need to deal with a deteriorating environment. Three areas of focus came out in discussion during Wood Mackenzie’s London Energy Forum - unrelated, different in scope and scale, each pointing the way forward.
First, clean air in cities. China has shown how to clean up a local environment quickly. The government reacted to poor air quality in Beijing and other major cities by closing older coal power plants and forcing energy intensive industry and the residential sector to shift away from coal. The country’s return on investment will include a substantial future health care dividend.
European cities are introducing restrictions on diesel cars to improve air quality. London’s 2017 “toxicity charge” is a precursor of an Ultra-Low Emission Zone in 2019, and aligns with UK net-zero policy changes that affect transport planning, to be extended across much of the city by 2020. Paris wants to ban diesel cars from the city centre by 2025 and ICE vehicles by 2030. Barcelona, Madrid, Hamburg and Stuttgart are hatching similar plans.
College Promise In California: Community-Wide Efforts To Support Student Success
Second, desulphurisation of global shipping. High sulphur fuel oil (HSFO) meets around 3.5 million barrels per day (b/d) of the total marine market of 5 million b/d. A maximum of 3.5% sulphur content is allowed currently. The International Maritime Organisation (IMO) implements a 0.5% limit on all shipping in 2020, dramatically reducing the release of sulphur oxides into the atmosphere.
Some ships will switch to very low sulphur fuel oil, of which only around 1.4 million b/d will be available in 2020. Others will have to choose between investing in scrubbers or buying premium-priced low sulphur marine gas oil.
Longer-term, lower carbon-intensity gas is a winner as liquefied natural gas becomes fuel of choice for many newbuilds. Marine LNG demand climbs from near zero to 50 million tonnes per annum (tpa) by 2040 on our forecasts, behind only China, India and Japan as a demand centre. LNG will displace over 1 million b/d of oil demand in shipping by 2040.
Third, Europe’s radical decarbonisation plans. Already in the vanguard of emissions reductions policy, the European Commission is proposing to reduce carbon emissions for new cars and vans by 30% by 2030 versus 2020. The targets come with incentives for car manufacturers linked to the uptake of EVs.
The 2050 roadmap, presently at the concept stage, envisages a far more demanding regime, with EU electricity plans for 2050 implying a much larger power system. The mooted 80% reduction in emissions compared with 1990 will embrace all sectors. Power and transport are already moving in this direction, but the legacy fuel mix in many other sectors will be disrupted, too.
Near zero-energy buildings and homes might be possible with energy efficiency improvements, renewables and heat pumps. Electrification, recycling and bioenergy could reduce fossil fuel use in energy intensive sectors like steel and aluminium, and Europe’s oil majors going electric illustrates how incumbents are adapting. Some sectors will cite the risk decarbonisation poses to Europe’s global competitiveness. If change is to come, industry will need to build new partnerships with society to meet these targets.
The 2050 roadmap signals the ambition and will be game changing for Europe if it is adopted. It would provide a template for a global roll out that would go a long way toward meeting UN’s concerns.
BC Hydro SAP Oversight Report assesses B.C. Utilities Commission findings on misleading testimony, governance failures, public funds oversight, IT project risk, compliance gaps, audit controls, ratepayer impacts, and regulatory accountability in major enterprise software decisions.
Key Points
A summary of BCUC findings on BC Hydro's SAP IT project oversight, governance lapses, and regulatory compliance.
✅ BCUC probed testimony, cost overruns, and governance failures
✅ Project split to avoid scrutiny; incomplete records and late corrections
✅ Reforms pledged: stronger business cases, compliance, audit controls
B.C. Hydro misled the province’s independent regulator about an expensive technology program, thereby avoiding scrutiny on how it spent millions of dollars in public money, according to a report by the B.C. Utilities Commission.
The Crown power corporation gave inaccurate testimony to regulators about the software it had chosen, called SAP, for an information technology project that has cost $197 million, said the report.
“The way the SAP decision was made prevented its appropriate scrutiny by B.C. Hydro’s board of directors and the BCUC, reflecting governance risks seen in Manitoba Hydro board changes in other jurisdictions,” the commission found.
“B.C. Hydro’s CEO and CFO and its (audit and risk management board committee) members did not exhibit good business judgment when reviewing and approving the SAP decision without an expenditure approval or business case, highlighting how board upheaval at Hydro One can carry market consequences.”
The report was the result of a complaint made in 2016 by then-opposition NDP MLA Adrian Dix, who alleged B.C. Hydro lied to the regulatory commission to try to get approval for a risky IT project in 2008 that then went over budget and resulted in the firing of Hydro’s chief information officer.
The commission spent two years investigating. Its report outlined how B.C. Hydro split the IT project into smaller components to avoid scrutiny, failed to produce the proper planning document when asked, didn’t disclose cost increases of up to $38 million, reflecting pressures seen at Manitoba Hydro's debt across the sector, gave incomplete testimony and did not quickly correct the record when it realized the mistakes.
“Essentially all of the things I asserted were substantiated, and so I’m pleased,” Dix, who is now minister of health, said on Monday. “I think ratepayers can be pleased with it, because even though it was an elaborate process, it involves hundreds of millions of spending by a public utility and it clearly required oversight.”
The BCUC stopped short of agreeing with Dix’s allegation that the errors were deliberate. Instead it pointed toward a culture at B.C. Hydro of confusion, misunderstanding and fear of dealing with the independent regulatory process.
“Therefore, the panel finds that there was a culture of reticence to inform the BCUC when there was doubt about something, even among individuals that understood or should have understood the role of the BCUC, a pattern that can fuel Hydro One investor concerns in comparable markets,” read the report.
“Because of this doubt and uncertainty among B.C. Hydro staff, the panel finds no evidence to support a finding that the BCUC was intentionally misled. The panel finds B.C. Hydro’s culture of reticence to be inappropriate.”
By law, B.C. Hydro is supposed to get approval by the commission for rate changes and major expenditures. Its officials are often put under oath when providing information.
B.C. Hydro apologized for its conduct in 2016. The Crown corporation said Monday it supports the commission’s findings and has made improvements to management of IT projects, including more rigorous business case analyses.
“We participated fully in the commission’s process and acknowledged throughout the inquiry that we could have performed better during the regulatory hearings in 2008,” said spokesperson Tanya Fish.
“Since then, we have taken steps to ensure we meet the highest standards of openness and transparency during regulatory proceedings, including implementing a (thorough) awareness program to support staff in providing transparent and accurate testimony at all times during a regulatory process.”
The Ministry of Energy, which is responsible for B.C. Hydro, said in a statement it accepts all of the BCUC recommendations and will include the findings as part of a review it is conducting into Hydro’s operations and finances, including its deferred operating costs for context, and regulatory oversight.
Dix, who is now grappling with complex IT project management in his Health Ministry, said the lessons learned by B.C. Hydro and outlined in the report are important.
“I think the report is useful reading on all those scores,” he said. “It’s a case study in what shouldn’t happen in a major IT project.”
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.
