South Dakota PUC fuel clause rider delay scrutinizes Xcel Energy and Northern States Power PPAs, Minnesota solar mandate costs, and a proposed 3 cents/kWh rate increase under utility regulation and fuel cost adjustment review.
Key Points
A 180-day review to assess Xcel fuel rider impacts from Minnesota solar PPAs before approving a 3 cents/kWh increase.
✅ 180-day extension to evaluate fuel clause rider impacts
✅ Review Minnesota solar PPAs and cost allocation
✅ Proposed increase about 3 cents/kWh to customers
The South Dakota Public Utilities Commission decided to delay a decision over a fuel clause rider requested by Xcel Energy subsidiary Northern State Power for 180 days to examine if solar costs in Minnesota account for some of the rate increase, the Capital Journal reports. A new Minnesota law requires the state’s utilities to receive at least 1.5% of their electricity from solar generation by 2030, and the state’s 100% carbon-free by 2040 mandate is also a factor. The delay will allow South Dakota officials to “take a closer look” at the proposed increase, PUC lawyer Kristen Edwards told media outlets.
The utility is purchasing electricity from three new solar-power installations in Minnesota amid ongoing utility influence over solar markets debates: the 62.5-MW Marshall solar project, owned by NextEra Energy, four miles east of Marshall, the 100-MW North Star project in Chisago County, and the 100-MW Aurora project that is spread across 16 sites.
South Dakota PUC Chairman Chris Nelson said he does not want ratepayers in the state charged more than they should be, as some utilities pursue higher fixed charges elsewhere, for political decisions in Minnesota. The increase would come to about 3 cents/kWh.
In a request filed Nov. 30, PUC staff said it “believes it is necessary to evaluate the resource to determine whether the [power purchase agreement] is reasonable and cost effective considering other electricity alternatives.” Commissioner Gary Hanson said he is always concerned about Colorado and Minnesota because those states do things in ways that South Dakota doesn’t, amid intense rooftop solar policy battles nationally. “This is something I’m always concerned with,” he said.
The investigation will specifically look at the fuel clause rider filed by Xcel. Xcel representative Jim Wilcox said the company understands the commission’s desire and accepts the staff’s request, noting that similar rate pressures like SaskPower’s 8% rate hike have drawn scrutiny elsewhere.
Pumped Storage Hydroelectricity balances renewable energy, stabilizes the grid, and provides large-scale energy storage using reservoirs and reversible turbines, delivering flexible peak power, frequency control, and rapid response to variable wind and solar generation.
Key Points
A reversible hydro system that stores energy by pumping water uphill, then generates flexible peak power.
✅ Balances variable wind and solar with rapid ramping
✅ Stores off-peak electricity in upper reservoirs
✅ Enhances grid stability, frequency control, and reserves
The expense of hydroelectricity is moderately low, making it a serious wellspring of sustainable power. The hydro station burns-through no water, dissimilar to coal or gas plants. The commonplace expense of power from a hydro station bigger than 10 megawatts is 3 to 5 US pennies for every kilowatt hour, and Niagara Falls powerhouse upgrade projects show how modernization can further improve efficiency and reliability. With a dam and supply it is likewise an adaptable wellspring of power, since the sum delivered by the station can be shifted up or down quickly (as meager as a couple of moments) to adjust to changing energy requests.
When a hydroelectric complex is developed, the task creates no immediate waste, and it for the most part has an extensively lower yield level of ozone harming substances than photovoltaic force plants and positively petroleum product fueled energy plants, with calls to invest in hydropower highlighting these benefits. In open-circle frameworks, unadulterated pumped storage plants store water in an upper repository with no normal inflows, while pump back plants use a blend of pumped storage and regular hydroelectric plants with an upper supply that is renewed to a limited extent by common inflows from a stream or waterway.
Plants that don't utilize pumped capacity are alluded to as ordinary hydroelectric plants, and initiatives focused on repowering existing dams continue to expand clean generation; regular hydroelectric plants that have critical capacity limit might have the option to assume a comparable function in the electrical lattice as pumped capacity by conceding yield until required.
The main use for pumped capacity has customarily been to adjust baseload powerplants, however may likewise be utilized to decrease the fluctuating yield of discontinuous fuel sources, while emerging gravity energy storage concepts broaden long-duration options. Pumped capacity gives a heap now and again of high power yield and low power interest, empowering extra framework top limit.
In specific wards, power costs might be near zero or once in a while negative on events that there is more electrical age accessible than there is load accessible to retain it; despite the fact that at present this is infrequently because of wind or sunlight based force alone, expanded breeze and sun oriented age will improve the probability of such events.
All things considered, pumped capacity will turn out to be particularly significant as an equilibrium for exceptionally huge scope photovoltaic age. Increased long-distance bandwidth, including hydropower imports from Canada, joined with huge measures of energy stockpiling will be a critical piece of directing any enormous scope sending of irregular inexhaustible force sources. The high non-firm inexhaustible power entrance in certain districts supplies 40% of yearly yield, however 60% might be reached before extra capaciy is fundamental.
Pumped capacity plants can work with seawater, despite the fact that there are extra difficulties contrasted with utilizing new water. Initiated in 1966, the 240 MW Rance flowing force station in France can incompletely function as a pumped storage station. At the point when elevated tides happen at off-top hours, the turbines can be utilized to pump more seawater into the repository than the elevated tide would have normally gotten. It is the main enormous scope power plant of its sort.
Alongside energy mechanism, pumped capacity frameworks help control electrical organization recurrence and give save age. Warm plants are substantially less ready to react to abrupt changes in electrical interest, and can see higher thermal PLF during periods of reduced hydro generation, conceivably causing recurrence and voltage precariousness.
Pumped storage plants, as other hydroelectric plants, including new BC generating stations, can react to stack changes in practically no time. Pumped capacity hydroelectricity permits energy from discontinuous sources, (for example, sunlight based, wind) and different renewables, or abundance power from consistent base-load sources, (for example, coal or atomic) to be put something aside for times of more popularity.
The repositories utilized with siphoned capacity are tiny when contrasted with ordinary hydroelectric dams of comparable force limit, and creating periods are regularly not exactly a large portion of a day. This technique produces power to gracefully high top requests by moving water between repositories at various heights.
Now and again of low electrical interest, the abundance age limit is utilized to pump water into the higher store. At the point when the interest gets more noteworthy, water is delivered once more into the lower repository through a turbine. Pumped capacity plans at present give the most monetarily significant methods for enormous scope matrix energy stockpiling and improve the every day limit factor of the age framework. Pumped capacity isn't a fuel source, and shows up as a negative number in postings.
Alberta Renewable Energy Market is accelerating as wind and solar prices fall, corporate PPAs expand, and a deregulated, energy-only system, AESO outlooks, and TIER policy drive investment across the province.
Key Points
An open, energy-only Alberta market where wind and solar growth is driven by corporate PPAs, AESO outlooks, and TIER.
✅ Corporate PPAs lower costs and hedge power price risk
✅ AESO forecasts and TIER policy support renewables
By Chris Varcoe, Calgary Herald
A few things are abundantly clear about the state of renewable energy in Alberta today.
First, the demise of Alberta’s Renewable Electricity Program (REP) under the UCP government isn’t going to see new projects come to a screeching halt.
In fact, new developments are already going ahead.
And industry experts believe private-sector companies that increasingly want to purchase wind or solar power are going to become a driving force behind even more projects in Alberta.
BluEarth Renewables CEO Grant Arnold, who spoke Wednesday at the Canadian Wind Energy Association conference, pointed out the sector is poised to keep building in the province, even with the end of the REP program that helped kick-start projects and triggered low power prices.
“The fundamentals here are, I think, quite fantastic — strong resource, which leads to really competitive wind prices . . . it’s now the cheapest form of new energy in the province,” he told the audience.
“Alberta is in a fundamentally good place to grow the wind power market.”
Unlike other provinces, Alberta has an open, deregulated marketplace, which create opportunities for private-sector investment and renewable power developers as well.
The recent decision by the Kenney government to stick with the energy-only market, instead of shifting to a capacity market, is seen as positive for Alberta's energy future by renewable electricity developers.
There is also increasing interest from corporations to buy wind and solar power from generators — a trend that has taken off in the United States with players such as Google, General Motors and Amazon — and that push is now emerging in Canada.
“It’s been really important in the U.S. for unlocking a lot of renewable energy development,” said Sara Hastings-Simon, founding director of the Business Renewable Centre Canada, which seeks to help corporate buyers source renewable energy directly from project developers.
“You have some companies where . . . it’s what their investors and customers are demanding. I think we will see in Alberta customers who see this as a good way to meet their carbon compliance requirements.
“And the third motivation to do it is you can get the power at a good price.”
Just last month, Perimeter Solar signed an agreement with TC Energy to supply the Calgary-based firm with 74 megawatts from its solar project near Claresholm.
More deals in the industry are being discussed, and it’s expected this shift will drive other projects forward.
There is increasing interest from corporations to buy solar and wind energy directly from generators.
“The single-biggest change has been the price of wind and solar,” Arnold said in an interview.
“Alberta looks really, really bright right now because we have an open market. All other provinces, for regulatory reasons, we can’t have this (deal) . . . between a generator and a corporate buyer of power. So Alberta has a great advantage there.”
These forces are emerging as the renewable energy industry has seen dramatic change in recent years in Alberta, with costs dropping and an array of wind and solar developments moving ahead, even as solar expansion faces challenges in the province.
The former NDP government had an aggressive target to see green energy sources make up 30 per cent of all electricity generation by 2030.
Last week, the Alberta Electric System Operator put out its long-term outlook, with its base-case scenario projecting moderate demand growth for power over the next two decades. However, the expected load growth — expanding by an average of 0.9 per cent annually until 2039 — is only half the rate seen in the past 20 years.
Natural gas will become the main generation source in the province as coal-fired power (now comprising more than one-third of generation) is phased out.
Renewable projects initiated under the former NDP government’s REP program will come online in the near term, while “additional unsubsidized renewable generation is expected to develop through competitive market mechanisms and support from corporate power purchase agreements,” the report states.
AESO forecasts installed generation capacity for renewables will almost double to about 19 per cent by 2030, with wind and solar increasing to 21 per cent by 2039.
Another key policy issue for the sector will likely come within the next few weeks when the provincial government introduces details of its new Technology Innovation and Emissions Reduction program (TIER).
The initiative will require large industrial emitters to reduce greenhouse gas emissions to a benchmark level, pay into the technology fund, or buy offsets or credits. The carbon price is expected to be around $20 to $30 a tonne, and the system will kick in on Jan. 1, 2020.
Industry players point out the decision to stick with Alberta’s energy-only market along with the details surrounding TIER, and a focus by government on reducing red tape, should all help the sector attract investment.
“It is pretty clear there is a path forward for renewables here in the province,” said Evan Wilson, regional director with the Canadian Wind Energy Association.
All of these factors are propelling the wind and solar sector forward in the province, at the same time the oil and gas sector faces challenges to grow.
But it doesn’t have to be an either/or choice for the province moving forward. We’re going to need many forms of energy in the coming decades, and Alberta is an energy powerhouse, with potential to develop more wind and solar, as well as oil and natural gas resources.
“What we see sometimes is the politics and discussion around renewables or oil becomes a deliberate attempt to polarize people,” Arnold added.
“What we are trying to show, in working in Alberta on renewable projects, is it doesn’t have to be polarizing. There are a lot of solutions.
“The combination of solutions is part of what we need to talk about.”
New York Climate Transition Costs highlight rising utility bills for ratepayers as the state pursues renewable energy, electrification, and a zero-emissions grid, with Inflation Reduction Act funding to offset consumer burdens while delivering health benefits.
Key Points
Ratepayer-funded costs to meet New York's renewable targets and zero-emissions grid, offset by federal incentives.
✅ $48B in projects funded by consumers over two decades
✅ Up to 10% of utility bills already paid by some upstate users
✅ Targets: 70% renewables by 2030; zero-emissions grid by 2040
A generational push to tackle climate change in New York that includes its Green New Deal is quickly becoming a pocketbook issue headed into 2024.
Some upstate New York electric customers are already paying 10 percent of their electricity bills to support the state’s effort to move off fossil fuels and into renewable energy. In the coming years, people across the state can expect to give up even bigger chunks of their income to the programs — $48 billion in projects is set to be funded by consumers over the next two decades.
The scenario is creating a headache for New York Democrats grappling with the practical and political risk of the transition.
It’s an early sign of the dangers Democrats across the country will face as they press forward with similar policies at the state and federal level. New Jersey, Maryland and California are also wrestling with the issue and, in some cases, are reconsidering their ambitious plans, including a 100% carbon-free mandate in California.
“This is bad politics. This is politics that are going to hurt all New Yorkers,” said state Sen. Mario Mattera, a Long Island Republican who has repeatedly questioned the costs of the state’s climate law and who will pay for it.
Democrats, Mattera said, have been unable to explain effectively the costs for the state’s goals. “We need to transition into renewable energy at a certain rate, a certain pace,” he said.
Proponents say the switch will ultimately lower energy bills by harnessing the sun and wind, result in significant health benefits and — critically — help stave off the most devastating climate change scenarios. And they hope new money to go green from the Inflation Reduction Act, celebrating its one-year anniversary, can limit costs to consumers.
New York has statutory mandates calling for 70 percent renewable electricity by 2030 and a fully “zero emissions” grid by 2040, among the most aggressive targets in the country, aligning with a broader path to net-zero electricity by mid-century. The grid needs to be greened, while demand for electricity is expected to more than double by 2050 — the same year when state law requires emissions to be cut by 85 percent from 1990 levels.
But some lawmakers in New York, particularly upstate Democrats, and similar moderates across the nation are worried about moving too quickly and sparking a backlash against higher costs, as debates over Minnesota's 2050 carbon-free plan illustrate. The issue is another threat to Democrats heading into the critical 2024 battleground House races in New York, which will be instrumental in determining control of Congress.
Even Gov. Kathy Hochul, a Democrat who is fond of saying that “we’re the last generation to be able to do anything” about climate change, last spring balked at the potential price tag of a policy to achieve New York’s climate targets, a concern echoed in debates over a fully renewable grid by 2030 elsewhere. And she’s not the only top member of her party to say so.
“If it’s all just going to be passed along to the ratepayers — at some point, there’s a breaking point, and we don’t want to lose public support for this agenda,” state Comptroller Tom DiNapoli, a Democrat, warned in an interview.
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.”
US Electricity Price Surge drives bills as BLS data show 15.8 percent jump; natural gas and coal costs escalate amid energy crisis, NYISO warns of wholesale prices and winter futures near $200 per MWh.
Key Points
A sharp rise in power bills driven by higher natural gas and coal costs and tighter wholesale markets.
✅ BLS reports electricity bills up 15.8% year over year
✅ Natural gas bills up 33% as fuel costs soar
✅ NYISO flags winter wholesale prices near $200/MWh
Electricity bills for US consumers jumped the most since 1981, gaining 15.8% from the same period a year ago, according to the US Bureau of Labor Statistics, and residential bills rose 5% in 2022 across the U.S.
Natural gas bills, which crept back up last month after dipping in July, surged 33% from the same month last year, labor data released Tuesday showed, as electricity and natural gas pricing dynamics continue to ripple through markets. Broader energy costs slipped for a second consecutive month because of lower gasoline and fuel oil prices. Even with that drop, total energy costs were still about 24% above August 2021 levels.
Electricity costs are relentlessly climbing because prices for the two biggest power-plant fuels -- natural gas and coal -- have surged in the last year as the US economy rebounds from the pandemic and as Russia’s war in Ukraine triggers an energy crisis in Europe, where German electricity prices nearly doubled over a year. Another factor is the hot and humid summer across most of the lower 48 states drove households and businesses to crank up air conditioners. Americans likely used a record amount of power in the third quarter, according to US Energy Information Administration projections, even as U.S. power demand is seen sliding 1% in 2023 on milder weather.
New York’s state grid operator warned of a “sharp rise in wholesale electric costs expected this winter” with spiking global demand for fossil fuels, lagging supply and instability from Russia’s war in Ukraine driving up oil and gas prices, with multiple energy-crisis impacts on U.S. electricity and gas still unfolding, according to a Tuesday report. Geopolitical factors are ultimately reflected in wholesale electricity prices and supply charges to consumer bills, the New York Independent System Operator said, and as utilities direct more spending to delivery rather than production.
Electricity price futures for this winter have increased fourfold from last year, and potential deep-freeze disruptions to the energy sector could add volatility, with prices averaging near $200 a megawatt-hour, the grid operator said. That has been driven by natural gas futures for the upcoming winter, which are more than double current prices to nearly $20 per million British thermal units.
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.
