Aircraft safety is replacing air pollution concerns as the latest obstacle potentially jeopardizing plans to build two power plants in west Hayward.
High-velocity plumes generated from power plant heat stacks "have a potential to pose a hazard to aircraft" flying to and from the Hayward Executive Airport, according to a letter sent by the California Energy Commission to city officials.
Paul Richins, a manager in the state commission's siting division, wrote that the hot, mostly invisible plumes can disturb the stability of the atmosphere above plants, especially in the winter.
"Plumes are thermally buoyant during colder weather and more likely to maintain their vertical velocity at higher altitudes under calm, cool conditions," Richins wrote.
Hayward's busy general aviation airport is a little more than a mile north of where Texas-based Tierra Energy wants to build its 115-megawatt Eastshore Energy Center on Clawiter Road.
San Jose-based Calpine Corp. also wants to build the much bigger, 600-megawatt Russell City Energy Center about a half-mile west of the Eastshore plant.
Both power plants would serve the Pacific Gas & Electric grid. And both plants, if built, are expected to emit plumes that exit from heat stacks at a velocity ranging from 71 to 74 feet per second, Richins said.
For the Russell City plant, the plumes would emerge from two 145-foot-tall stacks near Hayward's wastewater treatment plant on Enterprise Avenue. For the Eastshore plant, emissions would emerge from 14 stacks that each would be 70 feet tall.
The Russell City plant would also have nine 64-foot-tall cooling towers emitting additional plumes estimated to rise at 34 feet per second. The Eastshore plant would not have any cooling towers and would not emit any visible plumes.
State energy officials began scrutinizing the aircraft safety issues in Hayward because of concerns that have arisen over power plant proposals in the southeastern California city of Blythe.
Charles Hull, manager of the Blythe Municipal Airport, said a power plant was built in 2001 on a site a mile west of his airport. Another power plant is scheduled to be built nearby soon.
There have been no airplane accidents associated with the existing plant, though some pilots have registered turbulence complaints, Hull said. And in colder winter months, the plant sometimes produces a wet column of air.
"It's a very sensitive issue," Hull said. "You can't have an airport all of a sudden consumed by a cloud."
Partly because of those concerns, staffers at the California Energy Commission advised the commission in 2005 against building a second Blythe power plant, saying the location "creates a potential adverse airport safety impact."
The commission, which has final say on whether a plant will be built, allowed the plant a license anyway but placed a condition on the developer to mitigate air safety hazards.
Hull, who is also Blythe's assistant city manager, said the airport established an airfield wind-advisory system that takes wind and temperature measurements. The state also made power plant operators implement various safety measures.
Susanne Garfield, a spokeswoman for the energy commission, said that because of the Blythe plant, officials now have a better understanding of the impacts of thermal plumes.
Greg Trewitt, a Tierra Energy vice president and manager of the Eastshore project, said the company is prepared to work with the Federal Aviation Administration to study and address potential air safety hazards.
"I think the CEC is just making sure it is not a hazard," Trewitt said of the letter. "We'll have to work with the FAA and make sure we're not creating any issues with overflying aircraft."
FERC Transmission Planning Overhaul streamlines interregional grid buildouts, enabling high-voltage lines, renewable integration, and grid reliability to scale, cutting fossil reliance while boosting decarbonization, climate resilience, and affordability across regions facing demand and extreme weather.
Key Points
Federal rule updating interregional grid planning to integrate renewables, share costs, and improve reliability.
✅ Accelerates high-voltage, interregional lines for renewable transfer
✅ Optimizes transmission planning and cost allocation frameworks
✅ Boosts grid reliability, resilience, and emissions reductions
The US took a significant step towards a cleaner energy future on May 13th, 2024. The Federal Energy Regulatory Commission (FERC) approved the first major update to the country's electric transmission policy in over a decade, while congressional Democrats continue to push for action on aggregated DERs within FERC's remit today. This overhaul aims to streamline the process of building new power lines, specifically those that connect different regions. This improved connectivity is crucial for integrating more renewable energy sources like wind and solar into the national grid.
The current system faces challenges in handling the influx of renewables, and the aging U.S. grid amplifies those hurdles today. Renewable energy sources are variable by nature – the sun doesn't always shine, and the wind doesn't always blow. Traditionally, power grids have relied on constantly running power plants, like coal or natural gas, to meet electricity demands. These plants can be easily adjusted to produce more or less power as needed. However, renewable energy sources require a different approach.
The new FERC policy focuses on building more interregional transmission lines. These high-voltage power lines would allow electricity generated in regions with abundant solar or wind power, and even enable imports of green power from Canada in certain corridors, to be transmitted to areas with lower renewable energy resources. For example, solar energy produced in sunny states like California could be delivered to meet peak demand on the East Coast during hot summer days.
This improved connectivity offers several advantages. Firstly, it allows for a more efficient use of renewable resources. Secondly, it reduces the need for fossil fuel-based power plants, leading to cleaner air and lower greenhouse gas emissions. Finally, a more robust grid is better equipped to handle extreme weather events, which are becoming increasingly common due to climate change, and while Biden's climate law shows mixed results on decarbonization, stronger transmission supports resilience.
The need for an upgrade is undeniable. The Biden administration has set ambitious goals for decarbonizing the power sector by 2035, including proposals for a clean electricity standard as a pathway to those targets. A study by the US Department of Energy estimates that achieving this target will require more than doubling the country's regional transmission capacity and increasing interregional capacity by more than fivefold. The aging US grid is already struggling to keep up with current demands, and without significant improvements, it could face reliability issues in the future.
The FERC's decision has been met with praise from environmental groups and renewable energy companies. They see it as a critical step towards achieving a clean energy future. However, some stakeholders, including investor-owned utilities, have expressed concerns about the potential costs associated with building new transmission lines, citing persistent barriers to development identified in recent Senate testimony. Finding the right balance between efficiency, affordability, and environmental responsibility will be key to the success of this initiative.
The road ahead won't be easy. Building new power lines is a complex process that can face opposition from local communities, and broader disputes over electricity pricing changes often complicate planning and approvals. However, the potential benefits of a modernized grid are significant. By investing in this overhaul, the US is taking a crucial step towards a more reliable, sustainable, and cleaner energy future.
Karpowership LNG powership in Senegal will supply 15% of the grid, a 235 MW floating power plant bound for Dakar, enabling fast deployment, base-load electricity, and cleaner natural gas generation for West Africa.
Key Points
A 235 MW floating plant supplying 15% of Senegal's grid with fast, reliable, lower-emission LNG electricity.
✅ Rapid deployment: commercial operations expected early October
✅ Cleaner natural gas conversion planned after six months
Turkey's Karpowership company, the designer and builder of the world's first floating power plants and the global brand of Karadeniz Holding, will meet 15% of Senegal's electricity needs from liquefied natural gas (LNG) with the 235-megawatt (MW) powership Ayşegül Sultan, which started its voyage from Turkey to Senegal, where an African Development Bank review of a coal plant is underway, on Sunday.
Karpowership, operating 22 floating power plants in more than 10 countries around the world, where France's first offshore wind turbine is now producing electricity, has invested over $5 billion in this area.
In a statement to members of the press at Karmarine Shipyard, Karpowership Trade Group Chair Zeynep Harezi said they aimed to provide affordable electricity to countries in need of electricity quickly and reliably, as projects like the Egypt-Saudi power link expand regional grids, adding that they could commission energy ships capable of generating the base electric charge of the countries, as tidal power in Nova Scotia begins supplying the grid, in a period of about a month.
Harezi recalled that Karpowership commissioned the first floating energy ship in 2007 in Iraq, followed by Lebanon, Ghana, Indonesia, Mozambique, Zambia, Gambia, Sierra Leone, Sudan, Cuba, Guinea Bissau and Senegal, while Scottish tidal power demonstrates marine potential as well. "We meet the electricity needs of 34 million people in many countries," she stressed. Harezi stated that the energy ships, all designed and produced by Turkish engineers, use liquid fuel, but all ships can covert to the second fuel.
Considering the impact of electricity production on the environment, Harezi noted that they plan to convert the entire fleet from liquid fuel to natural gas, with complementary approaches like power-to-gas in Europe helping integrate renewables. "With a capacity of 480 megawatts each, the world's largest floating energy vessels operate in Indonesia and Ghana. The conversion to gas has been completed in our project in Indonesia. We have also initiated the conversion of the Ghana vessel into gas," she said.
Harezi explained that they would continue to convert their fleets to natural gas in the coming period. "Our 235-MW floating electric vessel, the Ayşegül Sultan, sets sail today to meet 15% of Senegal's electricity needs on its own. After an approximately 20-day cruise, the vessel will reach Dakar, the capital of Senegal, and will begin commercial operation in early October," Harezi continued. "We plan to use liquid fuel as bridging fuel in the first six months. At the end of the first six months, we will start to produce electricity from LNG on our ship. Thus, Ayşegül Sultan will be the first project to generate electricity from LNG in Africa, while the world's most powerful tidal turbine is delivering power to the grid, officials said. Our floating power plant to be sent to Mozambique is designed to generate electricity from LNG. It is also scheduled to start operations in the next year."
BC Hydro COVID-19 Relief offers electricity bill credits for laid-off workers and small business support, announced by Premier John Horgan, while FortisBC customers face deferrals and billing arrangements across Kelowna, Okanagan, and West Kootenay.
Key Points
BC Hydro COVID-19 Relief gives bill credits to laid-off residents; FortisBC offers deferrals and payment plans.
✅ Credit equals 3x average monthly bill for laid-off BC Hydro users
✅ Small businesses on BC Hydro get three months bill forgiveness
✅ FortisBC waives late fees, no disconnections, offers deferrals
On April 1, B.C. Premier John Horgan announced relief for BC Hydro customers who are facing bills after being laid-off during the economic shutdown due to the COVID-19 epidemic, while the utility also explores time-of-use rates to manage demand.
“Giving people relief on their power bills lets them focus on the essentials, while helping businesses and encouraging critical industry to keep operating,” he said.
BC Hydro residential customers in the province who have been laid off due to the pandemic will see a credit for three times their average monthly bill and, similar to Ontario's pandemic relief fund, small businesses forced to close will have power bills forgiven for three months.
But a large region of the province which gets its power from FortisBC will not have the same bail out.
FortisBC is the electricity provider to the tens of thousands who live and work in the Silmikameen Valley on Highway 3, the city of Kelowna, the Okanagan Valley south from Penticton, the Boundary region along the U.S. border. as well as West Kootenay communities.
“We want to make sure our customers are not worried about their FortisBC bill,” spokesperson Nicole Brown said.
FortisBC customers will still be on the hook for bills despite measures being taken to keep the lights on, even as winter disconnection pressures have been reported elsewhere.
Recent storm response by BC Hydro also highlights how crews have kept electricity service reliable during recent atypical events.
“We’ve adjusted our billing practices so we can do more,” she said. “We’ve discontinued our late fees for the time being and no customer will be disconnected for any financial reason.”
Brown said they will work one-on-one with customers to help find a billing arrangement that best suits their needs, aligning with disconnection moratoriums seen in other jurisdictions.
Those arrangement, she said, could include a “deferral, an equal payment plan or other billing options,” similar to FortisAlberta's precautions announced in Alberta.
Global News inquired with the Premier’s office why FortisBC customers were left out of Wednesday’s announcement and were deferred to the Ministry of Energy, Mines and Petroleum Resources.
The Ministry referred us back to FortisBC on the issue and offered no other comment, even as peak rates for self-isolating customers remained unchanged in parts of Ontario.
“We’re examining all options of how we can further help our customers and look forward to learning more about the program that BC Hydro is offering,” Brown said.
Disappointed FortisBC customers took to social media to vent about the disparity.
California Rooftop Solar Rate Reforms propose shifting net metering to fixed access fees, peak-demand charges, and time-of-use pricing, aligning grid costs, distributed generation incentives, and retail rates for efficient, least-cost electricity and fair cost recovery.
Key Points
Policies replacing net metering with fixed fees, demand charges, and time-of-use rates to align costs and incentives.
✅ Large fixed access charge funds grid infrastructure
✅ Peak-demand pricing reflects capacity costs at system peak
✅ Time-varying rates align marginal costs and emissions
The California Public Service Commission has proposed revamping electricity rates for residential customers who produce electricity through their rooftop solar panels. In a recent New York Times op‐ed, former Governor Arnold Schwarzenegger argued the changes pose an existential threat to residential rooftop solar. Interest groups favoring rooftop solar portray the current pricing system, often called net metering, in populist terms: “Net metering is the one opportunity for the little guy to get relief, and they want to put the kibosh on it.” And conventional news coverage suggests that because rooftop solar is an obvious good development and nefarious interests, incumbent utilities and their unionized employees, support the reform, well‐meaning people should oppose it. A more thoughtful analysis would inquire about the characteristics and prices of a system that supplies electricity at least cost.
Currently, under net metering customers are billed for their net electricity use plus a minimum fixed charge each month. When their consumption exceeds their home production, they are billed for their net use from the electricity distribution system (the grid) at retail rates. When their production exceeds their consumption and the excess is supplied to the grid, residential consumers also are reimbursed at retail rates. During a billing period, if a consumer’s production equaled their consumption their electric bill would only be the monthly fixed charge.
Net metering would be fine if all the fixed costs of the electric distribution and transmission systems were included in the fixed monthly charge, but they are not. Between 66 and 77 percent of the expenses of California private utilities do not change when a customer increases or decreases consumption, but those expenses are recovered largely through charges per kWh of use rather than a large monthly fixed charge. Said differently, for every kWh that a PG&E solar household exported into the grid in 2019, it saved more than 26 cents, on average, while the utility’s costs only declined by about 8 cents or less including an estimate of the pollution costs of the system’s fossil fuel generators. The 18‐cent difference pays for costs that don’t change with variation in a household’s consumptions, like much of the transmission and distribution system, energy efficiency programs, subsidies for low‐income customers, and other fixed costs. Rooftop solar is so popular in California because its installation under a net metering system avoids the 18 cents, creating a solar cost shift onto non-solar customers. Rooftop solar is not the answer to all our environmental needs. It is simply a form of arbitrage around paying for the grid’s fixed costs.
What should electricity tariffs look like? This article in Regulation argues that efficient charges for electricity would consist of three components: a large fixed charge for the distribution and transmission lines, meter reading, vegetation trimming, etc.; a peak‐demand charge related to your demand when the system’s peak demand occurs to pay for fixed capacity costs associated with peak use; and a charge for electricity use that reflects the time‐ and location‐varying cost of additional electricity supply.
Actual utility tariffs do not reflect this ideal because of political concerns about the effects of large fixed monthly charges on low‐income customers and the optics of explaining to customers that they must pay 50 or 60 dollars a month for access even if their use is zero. Instead, the current pricing system “taxes” electricity use to pay for fixed costs. And solar net metering is simply a way to avoid the tax. The proposed California rate reforms would explicitly impose a fixed monthly charge on rooftop solar systems that are also connected to the grid, a change that could bring major changes to your electric bill statewide, and would thus end the fixed‐cost avoidance. Any distributional concerns that arise because of the effect of much larger fixed charges on lower‐income customers could be managed through explicit tax deductions that are proportional to income.
The current rooftop solar subsidies in California also should end because they have perverse incentive effects on fossil fuel generators, even as the state exports its energy policies to neighbors. Solar output has increased so much in California that when it ends with every sunset, natural gas generated electricity has to increase very rapidly. But the natural gas generators whose output can be increased rapidly have more pollution and higher marginal costs than those natural gas plants (so called combined cycle plants) whose output is steadier. The rapid increase in California solar capacity has had the perverse effect of changing the composition of natural gas generators toward more costly and polluting units.
The reforms would not end the role of solar power. They would just shift production from high‐cost rooftop to lower‐cost centralized solar production, a transition cited in analyses of why electricity prices are soaring in California, whose average costs are comparable with electricity production in natural gas generators. And they would end the excessive subsidies to solar that have negatively altered the composition of natural gas generators.
Getting prices right does not generate citizen interest as much as the misguided notion that rooftop solar will save the world, and recent efforts to overturn income-based utility charges show how politicized the debate remains. But getting prices right would allow the decentralized choices of consumers and investors to achieve their goals at least cost.
Iran Renewable Energy Strategy targets productivity first, then wind power expansion, investment, and exports, overcoming US sanctions, banking and forex limits, via private sector partnerships, precise wind maps, and regional grid interconnections.
Key Points
A policy prioritizing efficiency, wind deployment, and investor access while navigating US sanctions and currency limits.
✅ Prioritize efficiency, then scale wind generation capacity
✅ Leverage private sector, rial contracts, attract foreign capital
Deputy Energy Minister on Renewable Energies Affairs says the U.S. sanctions have currently affected the economic, banking and forex sectors of the country as the country‘s medicine is under sanctions and it means renewable energies are also under sanctions, and, globally, pandemic disruptions have compounded pressures on supply chains.
Speaking in a press conference yesterday, Mohammad Satkin said leading countries first focus on productivity then they turn to electricity production and the ministry in the first step has focused on productivity then on renewables, noting that renewables are now the cheapest new power in many regions, reiterating that the ministry will use all existing potentials in this regard especially in utilizing wind.
He added that the ministry is doing its best that the country would become the hub in the region for rush of investors and those who want take advantage of Iran’s experience in renewables, as markets like the U.S. scale renewables to a quarter of generation in coming years.
Satkin added that in the eastern part, the country has the biggest windy fields with capacity over 40mw. So the ministry is doing its best with full support of the private sector in equipping and investing in this field to carry out new policies.
He noted that in the past 12 years, wind potentials of the country have been under study, noting that country has three special channels in the east as one of them is north of Zabol which is very valuable in terms of energy and it has capability for construction of 2 to 3mw power station.
Satkin further said Khaf channel is the other one which has one of the most unique winds in the world, while Saudi wind expansion underscores regional momentum, and it can be developed for over 1000mw station. The windy region of Doroud is the third channel where the 50mw project has been kicked off there and it has capability for construction of some thousand-megawatt wind power station.
He added that Iran has prepared one of the most precise maps and it has even identified the border regions like with Afghanistan and perhaps in the future, Iran and Afghanistan may launch a joint project as Iran has enough expertise to offer its neighboring countries and as IRENA's decarbonisation roadmap highlights wider socio-economic benefits.
On signing agreement with foreign companies, Satkin said the ministry pays the sum of all contracts with domestic companies is paid in national currency rial as it is unable to pay in dollar or other currencies but Iranian companies may enjoy having foreign backings, including initiatives like ADFD-IRENA funding that support developing markets, and the ministry tries to attract foreign capital.
He also pointed to exports of renewables, adding that the government has authorized export of renewable energy but it needs proper planning to be assured of electricity production in order to export it to the neighboring states whenever they need, especially as Ireland targets over one-third green power within a few years.
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.
