The National Electrical Manufacturers Association (NEMA) has published OS 1-2008 Sheet-Steel Outlet Boxes, Device Boxes, Covers, and Box Supports and OS 2-2008 Nonmetallic Outlet Boxes, Device Boxes, Covers, and Box Supports.
OS 1-2008 and OS 2-2008 describe standard configurations for outlet boxes 100 cubic inches or less, as well as manufacturer specifications for materials, corrosion protection, dimensions of openings, supports, cover screws, markings, and provisions for grounding. The standards specify dimensions necessary for compatibility with NEMA standard wiring devices and help manufacturers ensure that box constructions comply with the National Electrical Code as well as UL listing requirements.
“OS 1 and OS 2 are the essential industry standards for maintaining compatibility of metal and nonmetallic outlet boxes with standardized wiring devices and conduit and cable systems,” said Daniel Kissane, chairman of the Outlet & Switch Box Section. “These revisions serve to increase both standards’ utility to manufacturers and building specifiers.”
The standards were last revised in 2003. Two of the changes made to OS 1 include additional marking requirements for boxes for ceiling-suspended fan support and clarification to marking requirements for clamps furnished as part of a box. OS 2 includes updated definitions, revised requirements for fixture boxes, and a modified Table 2-2.
The contents and scope of OS 1 may be viewed, or a hardcopy or electronic copy purchased for $129, by visiting www.nema.org/stds/os1.cfm. The contents and scope of OS 2 may be viewed, or a hardcopy or electronic copy purchased for $82, by visiting www.nema.org/stds/os2.cfm. Standards may also be purchased by contacting IHS at 800-854-7179 (within the U.S.), 303-397-7956 (international), 303-397-2740 (fax), or global.ihs.com.
NEMA is the association of electrical and medical imaging equipment manufacturers. Founded in 1926 and headquartered near Washington, D.C., its approximately 450 member companies manufacture products used in the generation, transmission and distribution, control, and end use of electricity.
Hybrid Electric Ships leverage marine batteries, LNG engines, and clean propulsion to cut emissions in shipping. From ferries to cargo vessels, electrification and sustainability meet IMO regulations, Corvus Energy systems, and dockside fast charging.
Key Points
Hybrid electric ships use batteries with diesel or LNG engines to cut fuel and emissions and meet stricter IMO rules.
✅ LNG or diesel gensets recharge marine battery packs.
✅ Cuts CO2, NOx, and particulate emissions in port and at sea.
✅ Complies with IMO standards; enables quiet, efficient operations.
The river is running strong and currents are swirling as the 150-metre-long Seaspan Reliant slides gently into place against its steel loading ramp on the shores of B.C.'s silty Fraser River.
The crew hustles to tie up the ship, and then begins offloading dozens of transport trucks that have been brought over from Vancouver Island.
While it looks like many vessels working the B.C. coast, below decks, the ship is very different. The Reliant is a hybrid, partly powered by electricity, and joins BC Ferries' hybrid ships in the region, the seagoing equivalent of a Toyota Prius.
Down below decks, Sean Puchalski walks past a whirring internal combustion motor that can run on either diesel or natural gas. He opens the door to a gleaming white room full of electrical cables and equipment racks along the walls.
"As with many modes of transportation, we're seeing electrification, from electric planes to ferries," said Puchalski, who works with Corvus Energy, a Richmond, B.C. company that builds large battery systems for the marine industry.
In this case, the batteries are recharged by large engines burning natural gas.
"It's definitely the way of the future," said Puchalski.
The 10-year-old company's battery system is now in use on 200 vessels around the world. Business has spiked recently, driven by the need to reduce emissions, and by landmark projects such as battery-electric high-speed ferries taking shape in the U.S.
"When you're building a new vessel, you want it to last for, say, 30 years. You don't want to adopt a technology that's on the margins in terms of obsolescence," said Puchalski. "You want to build it to be future-proof."
Dirty ships
For years, the shipping industry has been criticized for being slow to clean up its act. Most ships use heavy fuel oil, a cheap, viscous form of petroleum that produces immense exhaust. According to the European Commission, shipping currently pumps out about 940 million tonnes of CO2 each year, nearly three per cent of the global total.
That share is expected to climb even higher as other sectors reduce emissions.
When it comes to electric ships, Scandinavia is leading the world. Several of the region's car and passenger ferries are completely battery powered — recharged at the dock by relatively clean hydro power, and projects such as Kootenay Lake's electric-ready ferry show similar progress in Canada.
Tougher regulations and retailer pressure
The push for cleaner alternatives is being partly driven by worldwide regulations, with international shipping regulators bringing in tougher emission standards after a decade of talk and study, while financing initiatives are helping B.C. electric ferries scale up.
At the same time, pressure is building from customers, such as Mountain Equipment Co-op, which closely tracks its environmental footprint. Kevin Lee, who heads MEC's supply chain, said large companies are realizing they are accountable for their contributions to climate change, from the factory to the retail floor.
"You're hearing more companies build it into their DNA in terms of how they do business, and that's cool to see," said Lee. "It's not just MEC anymore trying to do this, there's a lot more partners out there."
In the global race to cut emissions, all kinds of options are on the table for ships, including giant kites being tested to harvest wind power at sea, and ports piloting hydrogen-powered cranes to cut dockside emissions.
Modern versions of sailing ships are also being examined to haul cargo with minimal fuel consumption.
But in practical terms, hybrids and, in the future, pure electrics are likely to play a larger role in keeping the propellers turning along Canada's coast, with neighboring fleets like Washington State Ferries' upgrade underscoring the shift.
UK Market Stability Outlook remains febrile as the Bank of England, Treasury, and OBR forecasts shape fiscal policy, interest rates, gilt yields, inflation, energy bills, and pound sterling, with Oct. 31 guidance to reassure investors.
Key Points
A view of investor confidence as BOE policy, fiscal plans, and energy aid shape inflation and interest rates.
✅ Markets await Oct. 31 fiscal statement and OBR projections
✅ Energy support design drives inflation and disposable income
✅ Pound weakness adds imported inflation; rates seen up 75 bps
Bank of England Deputy Governor Dave Ramsden said financial markets are still unsettled about the outlook for the UK and that a Treasury statement due on Oct. 31 may provide some reassurance.
Speaking to the Treasury Committee in Parliament, Ramsden said officials in government and the central bank are dealing with huge economic shocks, notably the surge in energy prices that came with Russia’s attack on Ukraine. Investors are reassessing where interest rates and the fiscal stance are headed.
“Markets remain quite febrile,” Ramsden told members of Parliament in London on Monday. “Things have not settled down yet.”
He described the events following Prime Minister Liz Truss’s ill-fated fiscal statement on Sept. 23, which set out a series of tax cuts funded by borrowing that spooked investors and triggered a rout in UK assets. Ramsden said those events damaged the UK’s credibility among investors, but reversing that program and Truss’s decision to step aside have helped the nation regain confidence.
“Credibility is hard won and easily lost,” Ramsden said. “That credibility is being recovered. That has to be followed through. A return to the kind of stability around policy making and around the framing of fiscal events will be really important.”
He said the issue with the Sept. 23 statement was that “it had one side of the fiscal arithmetic in it” and that the decision to include forecasts from the Office for Budget Responsibility will help underpin the confidence investors have in assessing the UK budget due out next week, including potential moves to end the link between gas and electricity prices for consumers.
“What we are going to get on Oct. 31 will be very important,” Ramsden said, “as it will address measures such as the price cap on household energy bills and other fiscal choices.”
“My sense is that will take account of all the statements on both the revenue and on the spending side.”
The central bank already was getting some information from Chancellor of the Exchequer Jeremy Hunt’s team about the fiscal statement due. Hunt said last week he’d curtail government plans to subsidize household fuel bills in April, when a 16% decrease in energy bills is anticipated, instead of letting it run as long as planned and replace it with a more targeted program.
“To the extent possible, we will obviously have a little bit of time to take account of that before we make our decisions later next week,” Ramsden said.
With Truss stepping down in the next day and handing power to Rishi Sunak, it isn’t certain the Oct. 31 statement will go ahead as planned. Ramsden’s remarks confirm reports that Hunt is preparing to make the statement, amid a free electricity debate in the industry, even before Sunak names his team.
Any hint about what sort of package Hunt will offer on energy is crucial to the BOE’s forecasts. Without aid for energy, consumers will be exposed to high winter heating and electricity costs and to the full force of whatever happens in natural gas and electricity markets, and that will have a big impact on how much disposable income is available to households.
The energy plan, alongside the energy security bill, “will be a key element, as obviously it will have a bearing on the path for inflation, which is critical, but also how much additional support relative to what we were assuming at the time of the September MPC there will be for households at different points in the income distribution,” Ramsden added.
Investors currently expect the BOE to hike rates by 75 basis points next week.
Ramsden also said the BOE is watching the pound’s decline to assess how that changes the outlook for inflation.
“We have to take account of it,” Ramsden said. “When sterling deprreciaties that feeds through to imported inflation. It’s fallen quite significantly. The overall trend is down.”
DOE CCUS Funding advances carbon capture, utilization, and storage with FEED studies, regional deployment, and CarbonSAFE site characterization, leveraging 45Q tax credits to scale commercial CO2 reduction across fossil energy sectors.
Key Points
DOE CCUS Funding are federal FOAs for commercial carbon capture, storage, and utilization via FEED and CarbonSAFE.
✅ $110M across FEED, Regional, and CarbonSAFE FOAs
✅ Supports Class VI permits, NEPA, and site characterization
✅ Enables 45Q credits and enhanced oil recovery utilization
The U.S. Department of Energy’s (DOE’s) Office of Fossil Energy (FE) has announced approximately $110 million in federal funding for cost-shared research and development (R&D) projects under three funding opportunity announcements (FOAs), alongside broader carbon-free electricity investments across the power sector.
Approximately $75M is for awards selected under two FOAs announced earlier this fiscal year; $35M is for a new FOA.
These FOAs further the Administration’s commitment to strengthening coal while protecting the environment. Carbon capture, utilization, and storage (CCUS) is increasingly becoming widely accepted as a viable option for fossil-based energy sources—such as coal- or gas-fired power plants under new EPA power plant rules and other industrial sources—to lower their carbon dioxide (CO2) emissions.
DOE’s program has successfully deployed various large-scale CCUS pilot and demonstration projects, and it is imperative to build upon these learnings to test, mature, and prove CCUS technologies at the commercial scale. A recent study by Science of the Total Environment found that DOE is the most productive organization in the world in the carbon capture and storage field.
“This Administration is committed to providing cost-effective technologies to advance CCUS around the world,” said Secretary Perry. “CCUS technologies are vital to ensuring the United States can continue to safely use our vast fossil energy resources, and we are proud to be a global leader in this field.”
“CCUS technologies have transformative potential,” said Assistant Secretary for Fossil Energy Steven Winberg. “Not only will these technologies allow us to utilize our fossil fuel resources in an environmentally friendly manner, but the captured CO2 can also be utilized in enhanced oil recovery and emerging CO2-to-electricity concepts, which would help us maximize our energy production.”
Under the first FOA award, Front-End Engineering Design (FEED) Studies for Carbon Capture Systems on Coal and Natural Gas Power Plants, DOE has selected nine projects to receive $55.4 million in federal funding for cost-shared R&D. The selected projects will support FEED studies for commercial-scale carbon capture systems. Find project descriptions HERE.
Under the second FOA award, Regional Initiative to Accelerate CCUS Deployment, DOE selected four projects to receive up to $20 million in federal funding for cost-shared R&D. The projects also advance existing research and development by addressing key technical challenges; facilitating data collection, sharing, and analysis; evaluating regional infrastructure, including CO2 storage hubs and pipelines; and promoting regional technology transfer. Additionally, this new regional initiative includes newly proposed regions or advanced efforts undertaken by the previous Regional Carbon Sequestration Partnerships (RCSP) Initiative. Find project descriptions HERE.
Elsewhere in North America, provincial efforts such as Quebec's and industry partners like Cascades are investing in energy efficiency projects to complement emissions-reduction goals.
Under the new FOA, Carbon Storage Assurance Facility Enterprise (CarbonSAFE): Site Characterization and CO2 Capture Assessment, DOE is announcing up to $35 million in federal funding for cost-shared R&D projects that will accelerate wide-scale deployment of CCUS through assessing and verifying safe and cost-effective anthropogenic CO2 commercial-scale storage sites, and carbon capture and/or purification technologies. These types of projects have the potential to take advantage of the 45Q tax credit, bolstered by historic U.S. climate legislation, which provides a tax credit for each ton of CO2 sequestered or utilized. The credit was recently increased to $35/metric ton for enhanced oil recovery and $50/metric ton for geologic storage.
Projects selected under this new FOA shall perform the following key activities: complete a detailed site characterization of a commercial-scale CO2 storage site (50 million metric tons of captured CO2 within a 30 year period); apply and obtain an underground injection control class VI permit to construct an injection well; complete a CO2capture assessment; and perform all work required to obtain a National Environmental Policy Act determination for the site.
Baima Hydropower Station advances China renewable energy on the Wujiang River, a Yangtze tributary in Chongqing; a 525 MW cascade project approved by NDRC, delivering 1.76 billion kWh and improving river shipping.
Key Points
An NDRC-approved 525 MW project on Chongqing's Wujiang River, producing 1.76 billion kWh and improving navigation.
✅ 10.2 billion yuan investment; final cascade plant on Wujiang in Chongqing
✅ Improves river shipping; relocation of 5,000 residents in Wulong
China plans to build a 525-MW hydropower station on the Wujiang River, a tributary of the Yangtze River, in Southwest China's Chongqing municipality, aligning with projects like the Lawa hydropower station elsewhere in the Yangtze basin.
The Baima project, the last of a cascade of hydropower stations on the section of the Wujiang River in Chongqing, has gotten the green light from the National Development and Reform Commission, China's state planning agency, even as some independent power projects elsewhere face uncertainty, such as the Siwash Creek project in British Columbia, the Chongqing Municipal Commission of Development and Reform said Monday.
The project, in Baima township of Wulong district, is expected to involve an investment of 10.2 billion yuan ($1.6 billion), as China explores compressed air generation to bolster grid flexibility, it said.
#google#
With a power-generating capacity of 525 MW, it is expected to generate 1.76 billion kwh of electricity a year, supporting efforts to reduce coal power production nationwide, and help improve the shipping service along the Wujiang River.
More than 5,000 local residents will be relocated to make room for the project, which forms part of a broader energy mix alongside advances in nuclear energy in China.
Ukraine Energy Grid Attacks intensify as missile strikes and drone raids hit power plants, substations, and transmission lines, causing blackouts, disrupted logistics, and humanitarian strain during winter, despite repairs, air defense, and allied aid.
Key Points
Missile and drone strikes on Ukraine's power grid to force blackouts, strain civilians, and disrupt military logistics.
✅ Targets: power plants, substations, transmission lines
✅ Goals: erode morale, disrupt logistics, force aid burdens
Russia’s continued strikes on Ukraine have taken a severe toll on the country’s critical infrastructure, particularly its energy grid, as Ukraine continues to keep the lights on despite sustained bombardment. In recent months, Western Ukraine has increasingly become a target of missile and drone attacks, leading to widespread power outages and compounding the challenges faced by the civilian population. These strikes aim to cripple Ukraine's resilience during a harsh winter season and disrupt its wartime operations.
Targeting Energy Infrastructure
Russian missile and drone assaults on Ukraine’s energy grid are part of a broader strategy to weaken the country’s morale and capacity to sustain the war effort. The attacks have primarily focused on power plants, transmission lines, and substations. Western Ukraine, previously considered a relative safe haven due to its distance from front-line combat zones, is now experiencing the brunt of this campaign.
The consequences of these strikes are severe. Rolling blackouts and unplanned outages have disrupted daily life for millions of Ukrainians, though authorities say there are electricity reserves that could stabilize supply if no new strikes occur, leaving homes without heating during freezing temperatures, hospitals operating on emergency power, and businesses struggling to maintain operations. The infrastructure damage has also affected water supplies and public transportation, further straining civilian life.
Aimed at Civilian and Military Impact
Russia’s targeting of Ukraine’s power grid has dual purposes. On one hand, it aims to undermine civilian morale by creating hardships during the cold winter months, even as Ukraine works to keep the lights on this winter through contingency measures. On the other, it seeks to hinder Ukraine’s military logistics and operations, which heavily rely on a stable energy supply for transportation, communications, and manufacturing of military equipment.
These attacks coincide with a broader strategy of attritional warfare, where Moscow hopes to exhaust Ukraine’s resources and diminish its ability to continue its counteroffensive operations. By disrupting critical infrastructure, Russia increases pressure on Ukraine's allies to step up humanitarian and military aid, stretching their capacities.
Humanitarian Consequences
The impact of these power cuts on the civilian population is profound. Millions of Ukrainians are enduring freezing temperatures without consistent access to electricity or heating. Vulnerable populations, such as the elderly, children, and those with disabilities, face heightened risks of hypothermia and other health issues.
Hospitals and healthcare facilities are under immense strain, relying on backup generators that cannot sustain prolonged use. In rural areas, where infrastructure is already weaker, the effects are even more pronounced, leaving many communities isolated and unable to access essential services.
Humanitarian organizations have ramped up efforts to provide aid, including distributing generators, warm clothing, and food supplies, while many households pursue new energy solutions to weather blackouts. However, the scale of the crisis often outpaces the resources available, leaving many Ukrainians to rely on their resilience and community networks.
Ukraine's Response
Despite the challenges, Ukraine has demonstrated remarkable resilience in the face of these attacks. The government and utility companies are working around the clock to repair damaged infrastructure and restore power to affected areas. Mobile repair teams and international assistance have played crucial roles in mitigating the impact of these strikes.
Ukraine’s Western allies have also stepped in to provide support. The European Union, the United States, and other countries have supplied Ukraine with energy equipment, financial aid, and technical expertise to help rebuild its energy grid, though recent decisions like the U.S. ending support for grid restoration complicate planning and procurement. Additionally, advanced air defense systems provided by Western nations have helped intercept some of the incoming missiles and drones, though not all attacks can be thwarted.
Russia’s Escalation Strategy
Russia’s focus on Western Ukraine reflects a shift in its strategy. Previously, attacks were concentrated on front-line areas and major urban centers in the east and south. However, by targeting the western regions, Moscow seeks to disrupt the relatively stable zones where displaced Ukrainians and critical supply chains are located.
Western Ukraine is also a hub for receiving and distributing international aid and military supplies. Striking this region not only undermines Ukraine’s internal stability but also sends a message to its allies about Russia’s willingness to escalate the conflict further.
Broader Implications
The attacks on Ukraine’s energy grid have broader geopolitical implications. By targeting infrastructure, Russia intensifies the pressure on Ukraine’s allies to continue providing support, even as Kyiv has at times helped Spain amid blackouts when capacity allowed, testing their unity and resolve. The destruction also poses long-term challenges for Ukraine’s post-war recovery, as rebuilding a modern and resilient energy system will require significant investments and time.
Moreover, these attacks highlight the vulnerability of civilian infrastructure in modern warfare, echoing that electricity is civilization amid winter conditions. The deliberate targeting of non-combatant assets underscores the need for international efforts to strengthen the protection of critical infrastructure and address the humanitarian consequences of such tactics.
The Russian attacks on Western Ukraine's power grid are a stark reminder of the devastating human and economic costs of the ongoing conflict. While Ukraine continues to demonstrate resilience and adaptability, the scale of destruction underscores the need for sustained international support. As the war drags on, the focus must remain on mitigating civilian suffering, rebuilding critical infrastructure, and pursuing a resolution that ends the violence and stabilizes the region.
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.
