The ENMAX Corporation recently placed the final panels on its head office roof to complete one of the largest solar installations in the city. Covering over 8,000 square feet, the system will produce enough energy annually to power approximately one third of computers and monitors at the companyÂ’s head office.
“We are committed to energy solutions that improve our direct use of cleaner sources of electricity,” said Gianna Manes, President and CEO, ENMAX Corporation. ”This solar installation will provide us with excellent knowledge and insight that we can apply to both our home solar product offering and the commercial line currently under development.”
The new system, installed at head office ENMAX Place, will provide about 57,000 kilowatt hours of renewable energy each year. The output will be monitored daily via a web-based program that provides real-time data.
ENMAX Energy Corporation is also celebrating a significant milestone. Adding up all the ENMAX Energy installed solar panels on homes across the province, more than one million kilowatt hours have been generated as of this summer this is roughly equivalent to how much electricity is needed to run 1,600 average homes for one month. The program consists of an innovative leasing offer and continues to gain speed as sign-ups increase year over year. The initiative is supported by the Climate Change and Emissions Management Corporation CCEMC. The CCEMCÂ’s mandate is to establish or participate in funding initiatives that reduce GHG emissions or improve AlbertaÂ’s ability to adapt to climate change.
Spring Storm Grid Risks highlight tornado outbreaks, flooding, power outages, and transmission disruptions, with NOAA flood outlooks, coal and barge delays, vulnerable nuclear sites, and distribution line damage demanding resilience, reliability, and emergency preparedness.
Key Points
Spring Storm Grid Risks show how tornadoes and floods disrupt power systems, fuel transport, and plants guide resilience.
✅ Tornado outbreaks and derechos damage distribution and transmission
✅ Flooding drives outages via treefall, substation and plant inundation
✅ Fuel logistics disrupted: rail coal, river barges, road access
The storm and tornado outbreak that recently barreled through the US Midwest, South and Mid-Atlantic was a devastating reminder of how much danger spring can deliver, despite it being the “milder” season compared to summer and winter.
Danger season is approaching, and the country is starting to see the impacts.
The event killed at least 32 people across seven states. The National Weather Service is still tallying up the number of confirmed tornadoes, which has already passed 100. Communities coping with tragedy are assessing the damage, which so far includes at least 72 destroyed homes in one Tennessee county alone, and dozens more homes elsewhere.
On Saturday, April 1–the day after the storm struck–there were 1.1 million US utility customers without power, even as EIA reported a January power generation surge earlier in the year. On Monday morning, April 3, there were still more than 80,000 customers in the dark, according to PowerOutage.us. The storm system brought disruptions to both distribution grids–those networks of local power lines you generally see running overhead to buildings–as well as the larger transmission grid in the Midwest, which is far less common than distribution-level issues.
While we don’t yet have a lot of granular details about this latest storm’s grid impacts, recent shifts in demand like New York City's pandemic power patterns show how operating conditions evolve, and it’s worth going through what else the country might be in for this spring, as well as in future springs. Moreover, there are steps policymakers can take to prepare for these spring weather phenomena and bolster the reliability and resilience of the US power system.
Heightened flood risk The National Oceanic Atmospheric Administration (NOAA) said in a recent outlook that about 44 percent of the United States is at risk of floods this spring, equating to about 146 million people. This includes most of the eastern half of the country, the federal agency said.
The agency also sees “major” flood risk potential in some parts of the Upper Mississippi River Basin, and relatively higher risk in the Sierra Nevada region, due in part to a historic snowpack in California.
Multiple components of the power system can be affected by spring floods.
Power lines – Floods can saturate soil and make trees more likely to uproot and fall onto power lines. This has been contributing to power outages during California’s recent heavy storms–called atmospheric rivers–that started over the winter. In other regions, soil moisture has even been used as a predictor of where power outages will occur due to hurricanes, so that utility companies are better prepared to send line repair crews to the right areas. Hurricanes are primarily a summer and fall phenomenon, and summer also brings grid stress from air conditioning demand in many states, so for now, during spring, they are less of a concern.
Fuel transport – Spring floods can hinder the transportation of fuels like coal. While it is a heavily polluting fossil fuel that is set to continue declining as a fuel source for US electricity generation, with the EIA summer outlook for wind and solar pointing to further shifts, coal still accounted for roughly 20 percent of the country’s generation in 2022.
About 70 percent of US coal is transported at least part of the way by trains. The rail infrastructure to transport coal from the Powder River Basin in Montana and Wyoming–the country’s primary coal source–was proven to be vulnerable to extreme floods in the spring of 2011, and even more extreme floods in the spring of 2019. The 2019 floods’ disruptions of coal shipments to power plants via rail persisted for months and into the summertime, also affecting river shipments of coal by barge. In June 2019, hundreds of barges were stalled in the Mississippi River, through which millions of tons of the fossil fuel are normally transported.
Power plants – Power plants themselves can also be at risk of flooding, since most of them are sited near a source of water that is used to create steam to spin the plants’ turbines, and conversely, low water levels can constrain hydropower as seen in Western Canada hydropower drought during recent reservoir shortfalls. Most US fossil fuel generating capacity from sources like methane gas, which recently set natural gas power records across the grid, and coal utilizes steam to generate electricity.
However, much of the attention paid to the flood risk of power plant sites has centered on nuclear plants, a key source of low-carbon electricity discussed in IAEA low-carbon electricity lessons that also require a water source for the creation of steam, as well as for keeping the plant cool in an emergency. To name a notable flood example here in the United States–both visually and substantively–in 2011, the Fort Calhoun nuclear plant in Nebraska was completely surrounded by water due to late-spring flooding along the Missouri River. This sparked a lot of concerns because it was just a few months after the March 2011 meltdown of the Fukushima Daiichi nuclear plant in Japan. The public was thankfully not harmed by the Nebraska incident, but this was unfortunately not an isolated incident in terms of flood risks posed to the US nuclear power fleet.
NnG Offshore Wind Farm restarts construction off Scotland, backed by EDF Renewables and ESB, CfD 2015, 54 turbines, powering 375,000 homes, 500 jobs, delivering GBP 540 million, with Covid-19 safety measures and staggered workforce.
Key Points
A 54-turbine Scottish offshore project by EDF Renewables and ESB, resuming to power 375,000 homes and support 500 jobs.
✅ Awarded a CfD in 2015; 54 turbines off Scotland's east coast.
✅ Projected to power 375,000 homes and deliver GBP 540 million locally.
✅ Staggered workforce return with Covid-19 control measures and oversight.
Neart Na Gaoithe (NnG) Offshore Wind Farm, owned by EDF Renewables and Irish firm ESB, stopped construction in March, even as the world's most powerful tidal turbine showcases progress in marine energy.
Project boss Matthias Haag announced last night the 54-turbine wind farm would restart construction this week, as the largest UK offshore wind farm begins supplying power, underscoring sector momentum.
Located off Scotland’s east coast, where wind farms already power millions of homes, it was awarded a Contract for Difference (CfD) in 2015 and will look to generate enough energy to power 375,000 homes.
It is expected to create around 500 jobs, and supply chain growth like GE's new offshore blade factory jobs shows wider industry momentum, while also delivering £540 million to the local economy.
Mr Haag, NnG project director, said the wind farm build would resume with a small, staggered workforce return in line social distancing rules, and with broader energy sector conditions, including Hinkley Point C setbacks that challenge the UK's blueprint.
He added: “Initially, we will only have a few people on site to put in place control measures so the rest of the team can start work safely later that week.
“Once that’s happened we will have a reduced workforce on site, including essential supervisory staff.
“The arrangements we have put in place will be under regular review as we continue to closely monitor Covid-19 and follow the Scottish Government’s guidance.”
NnG wind farm, a 54-turbine projects, was due to begin full offshore construction in June 2020 before the Covid-19 outbreak, at a time when a Scottish tidal project had just demonstrated it could power thousands of homes.
EDF Renewables sold half of the NnG project to Irish firm ESB in November last year, and parent company EDF recently saw the Hinkley C reactor roof lifted into place, highlighting progress alongside renewables.
The first initial payment was understood to be around £50 million.
China Power Rationing disrupts the solar supply chain as coal shortages, price controls, and dual-control emissions policy curb electricity, squeezing polysilicon, aluminum, and module production and raising equipment costs amid surging post-Covid industrial demand.
Key Points
China's electricity curbs from coal shortages, price caps, and emissions targets disrupt solar output and materials.
✅ Polysilicon and aluminum output cut by power rationing
✅ Coal price spikes and power price caps squeeze generators
The solar manufacturing supply chain is among the industries being affected by a combination of soaring power demand, coal shortages, and carbon emission reduction measures which have seen widespread power cuts in China.
In Yunnan province, in southwest China, producers of the silicon metal which feeds polysilicon have been operating at 10% of the output they achieved in August. They are expected to continue to do so for the rest of the year as provincial authorities try to control electricity demand with a measure that is also affecting the phosphorus industry.
Fellow solar supply chain members from the aluminum industry in Guangxi province, in the south, have been forced to operate just two days per week, alongside peers in the concrete, steel, lime, and ceramics segments. Manufacturers in neighboring Guangdong have access to normal power supplies only on Fridays and Saturdays with electricity rationed to a 15% grid security load for the rest of the time.
pv magazine USA reported that a Tier 1 solar module manufacturer warned customers in an email that energy shortages in China have forced it to reduce or stop production at its Chinese manufacturing sites. The company warned the event will also affect output from its downstream cell and module production facilities in Southeast Asia.
The memo said that in order to recover from the effects of the “potential Force Majeure event,” it may delay or stop equipment delivery or seek to renegotiate contracts to pass through higher prices.
Raw material sourcing With reports of drastic power shortages emerging from China in recent days, the country has actually been experiencing problems since late June, and similar pressures have seen India ration coal supplies this year, but rationing is not unusual during the peak summer hours.
What has changed this time is that the outages have continued and prompted rationing measures across 19 of the nation’s provinces for the rest of the year. The problems have been caused by a combination of rising post-Covid electricity demand at a time when the politically-motivated ban on imports of Australian coal has tightened supply; and the manner in which Beijing controls power prices, with the situation further exacerbated by carbon emissions reduction policy.
Demand Electricity demand from industry, underscoring China’s electricity appetite, was 13.5 percentage points higher in the first eight months of the year than in the same period of 2020, at 3,585 TWh. That reflected a 13.8% year-on-year rise in total consumption, following earlier power demand drops when coronavirus shuttered plants, to 5.47 PWh, according to data from state energy industry trade body the China Electricity Council.
Figures produced by the China General Administration of Customs tell the same story: a rebound driven by the global recovery from the pandemic, as global power demand surges above pre-pandemic levels, with China recording import and export trade worth RMB2.48 trillion ($385 billion) in January-to-August. That was up 23.7% on the same period of last year and 22.8% higher than in the first eight months of 2019.
With Beijing having enforced an unofficial ban on imports of Australian coal for the last year or so – as the result of an ongoing diplomatic spat with Australia – rising demand for coal (which provided around 73% of Chinese electricity in the first half of the year) has further raised prices for the fossil fuel.
The problem for Chinese coal-fired power generators is that Beijing maintains strict controls on the price of electricity. As a result, input costs cannot be passed on to consumers. The mismatch between a liberalized coal market and centrally controlled end-user prices is illustrated by the current situation in Guangdong. There, a coal price of RMB1,560 per ton ($242) has pushed the cost of coal-fired electricity up to RMB0.472 per kilowatt-hour ($0.073). With coal power companies facing an electricity price ceiling of around RMB0.463/kWh ($0.071), generators are losing around RMB0.12 for every kilowatt-hour they generate. In that situation, rationing electricity supplies is an obvious remedy.
The crisis has been worsened by the introduction of China’s “dual control” energy policy, which aims to help meet President Xi Jinping’s climate change pledge of hitting peak carbon emissions this decade and a net zero economy by 2060, and to reduce coal power production over time. Dual control refers to attempts to wind down greenhouse gas emissions at both a national level and in more local areas, such as provinces and cities.
Red status With the finer details of the carbon reduction policy yet to be ironed out, government departments and provincial and city authorities have started to set their own emission-reduction targets. In mid-August, state planning body the China National Development and Reform Commission (NDRC) published a table of the energy control situation across the nation. With nine provinces marked red for their energy consumption, and a further 10 highlighted as yellow, officials received another motivation to introduce power rationing.
China’s solar industry is being impacted by coal shortages for electric power generation. In this 2014 photo, a thermal generating plant’s cooling towers loom over a street in Henan Province. Image: flickr/V.T. Polywoda
The current approach of rolling blackouts seems unlikely to be a sustainable solution, as surging electricity demand strains power systems worldwide, given the damage it could inflict on industry and the resentment it would cause in parts of the nation already preparing for winter.
The choice facing China’s policymakers is whether to ramp up coal supplies to force prices down by using decommissioned domestic supplies and halting the ban on Australian imports, or to raise electricity prices to prompt generators to get the lights back on. While the drawbacks of raising household electricity bills seem obvious, the first approach of using more coal could endanger the nation’s climate change commitments on the even of the COP26 meeting in Glasgow, Scotland, in November. Sources close to the NDRC have suggested the electricity price may be set to rise soon.
GDP What is clear is the effect the energy crisis is having on the Chinese economy and on the solar supply chain. Leading up to a national day holiday in China, the coal price in northern China rose to around RMB2,000 per ton ($310), three times higher than at the beginning of the year.
Investment bank China International Capital Corp. blamed the dual control emission reduction policy for the electricity shortages. It predicted a 0.1-0.15 percentage point impact on economic growth in the last quarter of 2021. Morgan Stanley has put that figure at 1% in the current quarter, if industrial output restrictions continue. And Japan’s Nomura Securities revised down its annual forecast on Chinese growth from 8.2% to 7.7%. It now expects GDP gains in the third and fourth quarters to cool from 5.1% to 4.7%, and from 4.4% to 3%, respectively.
Poland Offshore Wind Energy accelerates as PGE exits nuclear leadership, PKN Orlen steps in, and Baltic Sea projects expand to cut coal reliance, meet EU emissions goals, attract investors, and bridge the power capacity gap.
Key Points
A shift from coal and nuclear to Baltic offshore wind to add capacity, cut EU emissions, and attract investment.
✅ PGE drops lead in nuclear; pivots $10bn to offshore wind.
✅ PKN Orlen may assume nuclear role; projects await approval.
✅ 6 GW offshore could add 60b zlotys and 77k jobs by 2030.
PGE, Poland’s biggest power group has decided to abandon a role in building the country’s first nuclear power plant and will instead focus investment on offshore wind energy.
Reuters reports state-run refiner PKN Orlen (PKN.WA) could take on PGE’s role, while the latter announces a $10bn offshore wind power project.
Both moves into renewables and nuclear represent a major change in Polish energy policy, diversifying away from the country’s traditional coal-fired power base, as regional efforts like the North Sea wind farms initiative expand, in a bid to fill an electricity shortfall and meet EU emission standards.
An unnamed source told the news agency, PGE could not fund both projects and cheap technology had swung the decision in favour of wind, with offshore wind competing with gas in some markets. PGE could still play a smaller role in the nuclear project which has been delayed and still needs government approval.
#google#
A proposed law is currently before the Polish parliament aiming at facilitating easy construction of wind turbines, mindful of Germany’s grid expansion challenges that have hindered rollout.
If the law is passed, as expected, several other wind farm projects could also proceed.
Polenergia has said it would like to build a wind farm in the Baltic by 2022. PKN Orlen is also considering building one.
PGE said in March that it wants to build offshore windfarms with a capacity of 2.5 gigawatts (GW) by 2030.
Analysts and investors say that offshore wind farms are the easiest and fastest way for Poland to fill the expected capacity gap from coal, with examples like the largest UK offshore wind farm coming online underscoring momentum, and reduce CO2 emissions in line with EU’s 2030 targets as Poland seeks improved ties with Brussels.
The decision to open up the offshore power industry could also draw in investors, as shown by Japanese utilities’ UK offshore investment attracting cross-border capital. Statoil said in April it would join Polenergia’s offshore project which has drawn interest from other international wind companies. “
The Polish Wind Energy Association (PWEA) estimates that offshore windfarms with a total capacity of 6 GW would help create around 77,000 new jobs and add around 60 billion zlotys to economic growth.
Global Renewable LCOE Trends reveal offshore wind costs down 32%, with 10MW turbines, lower CAPEX and OPEX, and parity for solar PV and onshore wind in Europe, China, and California, per BloombergNEF analysis.
Key Points
Benchmarks showing falling LCOE for offshore wind, onshore wind, and solar PV, driven by larger turbines and lower CAPEX
✅ Offshore wind LCOE $78/MWh; $53-64/MWh in DK/NL excl. transmission
✅ Onshore wind $47/MWh; solar PV $51/MWh, best $26-36/MWh
✅ Cost drivers: 10MW turbines, lower CAPEX/OPEX, weak China demand
World offshore wind costs have fallen 32% from just a year ago and 12% compared with the first half of 2019, according to a BNEF long-term outlook from BloombergNEF.
In its latest Levelized Cost of Electricity (LCOE) Update, BloombergNEF said its current global benchmark LCOE estimate for offshore wind is $78 a megawatt-hour.
“New offshore wind projects throughout Europe, including the UK's build-out, now deploy turbines with power ratings up to 10MW, unlocking CAPEX and OPEX savings,” BloombergNEF said.
In Denmark and the Netherlands, it expects the most recent projects financed to achieve $53-64/MWh excluding transmission.
New solar and onshore wind projects have reached parity with average wholesale power prices in California and parts of Europe, while in China levelised costs are below the benchmark average regulated coal price, according to BloombergNEF.
The company's global benchmark levelized cost figures for onshore wind and PV projects financed in the last six months are at $47 and $51 a megawatt-hours, underscoring that renewables are now the cheapest new electricity option in many regions, down 6% and 11% respectively compared with the first half of 2019.
BloombergNEF said for wind this is mainly down to a fall in the price of turbines – 7% lower on average globally compared with the end of 2018.
In China, the world’s largest solar market, the CAPEX of utility-scale PV plants has dropped 11% in the last six months, reaching $0.57m per MW.
“Weak demand for new plants in China has left developers and engineering, procurement and construction firms eager for business, and this has put pressure on CAPEX,” BloombergNEF said.
It added that estimates of the cheapest PV projects financed recently – in India, Chile and Australia – will be able to achieve an LCOE of $27-36/MWh, assuming competitive returns for their equity investors.
Best-in-class onshore wind farms in Brazil, India, Mexico and Texas can reach levelized costs as low as $26-31/MWh already, the research said.
Programs such as the World Bank wind program are helping developing countries accelerate wind deployment as costs continue to drop.
BloombergNEF associate in the energy economics team Tifenn Brandily said: “This is a three- stage process. In phase one, new solar and wind get cheaper than new gas and coal plants on a cost-of- energy basis.
“In phase two, renewables reach parity with power prices. In phase three, they become even cheaper than running existing thermal plants.
“Our analysis shows that phase one has now been reached for two-thirds of the global population.
“Phase two started with California, China and parts of Europe. We expect phase three to be reached on a global scale by 2030.
“As this all plays out, thermal power plants will increasingly be relegated to a balancing role, looking for opportunities to generate when the sun doesn’t shine or the wind doesn’t blow.”
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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instruction, our electrical training courses can be
tailored to meet your company's specific requirements
and delivered to your employees in one location or at
various locations.
