A change in how TVA bills its distributors in April could be the first step toward persuading customers to use electricity during off-peak times in exchange for cheaper rates.
The Tennessee Valley Authority is restructuring the way it charges its 155 distributors, including Decatur Utilities and Joe Wheeler Electric Membership Cooperation, for the power it produces.
“This is a change for us as a distributor, but the rates for our customers will remain nearly flat,” DU General Manager Ray Hardin said. “In the long term, TVA’s goal is to send pricing signals to customers so they can use energy more efficiently.”
Hardin said a time-of-use rate option for Decatur is probably five to 10 years away because it would require DU to install new meters for all its customers. He said that would represent “a major investment.”
For now, TVA says the wholesale rate change is designed to be revenue neutral. Some distributors and their customers could see an annual increase or decrease within a 3 percent range either way.
TVA gave its distributors two wholesale rate options. One is based on seasonal demand. The other is based on costs to produce energy on a specific day and time.
DU chose the seasonal demand rate after comparing the costs of each option on its electric system, said Glenn Boyles, DU electric manager. Hardin said the seasonal demand rate option was the cheaper of the two.
Joe Wheeler EMC also chose the seasonal rate demand option, General Manager George Kitchens said.
The seasonal demand and energy rate option means charges to distributors will fluctuate to reflect the rising and falling demand, and thus, cost, of power seasonally. Peak demand in the summer and winter will drive up rates while off-peak periods in the spring and fall will push rates lower. The time-of-use option is similar, but it goes a step further. Rates are structured throughout peak and off-peak times during any given day in the year.
TVAÂ’s goal is eventually to get all of its distributors on the time-of-use rate structure because it is the most efficient way to determine the actual cost of power, said Scott Brooks, TVA spokesman. The logic is if consumers know the cheapest time to use electricity, they will change their behaviors and use power during those off-peak periods, such as late at night.
“We want to let the consumer drive the change in the amount of power they use,” Brooks said. “If we can reduce the amount of power TVA has to produce to meet customer demand, we won’t have to buy power on the open market or build expensive power plants.”
The cost of both of those are passed on to distributors and consumers.
The Tennessee Valley Authority announced a 2.5 percent increase in next month’s fuel cost adjustment — February: .436 cents per kilowatt-hour March: .613 cents per kilowatt-hour.
Average residential bill increase: Between $1.50 and $3.50 from February, based on 1,000 kilowatt-hours per month.
Reason: A planned unit outage at Browns Ferry Nuclear Plant in March means TVA will have to use more expensive fuels to meet demand.
Siwash Creek Hydroelectric Project faces downsizing under a BC Hydro power purchase agreement, with run-of-river generation, high grid interconnection costs, First Nations partnership, and surplus electricity from Site C reshaping clean energy procurement.
Key Points
A downsized run-of-river plant in BC, co-owned by Kanaka Bar and Green Valley, selling power via a BC Hydro PPA.
✅ Approved at 500 kW under a BC Hydro clean-energy program
✅ Grid interconnection initially quoted at $2.1M
✅ Joint venture: Kanaka Bar and Green Valley Power
A small run-of-river hydroelectric project recently selected by B.C. Hydro for a power purchase agreement may no longer be financially viable.
The Siwash Creek project was originally conceived as a two-megawatt power plant by the original proponent Chad Peterson, who holds a 50-per-cent stake through Green Valley Power, with the Kanaka Bar Indian Band holding the other half.
The partners were asked by B.C. Hydro to trim the capacity back to one megawatt, but by the time the Crown corporation announced its approval, it agreed to only half that — 500 kilowatts — under its Standing Order clean-energy program.
“Hydro wanted to charge us $2.1 million to connect to the grid, but then they said they could reduce it if we took a little trim on the project,” said Kanaka Bar Chief Patrick Michell.
The revenue stream for the band and Green Valley Power has been halved to about $250,000 a year. The original cost of running the $3.7-million plant, including financing, was projected to be $273,000 a year, according to the Kanaka Bar economic development plan.
“By our initial forecast, we will have to subsidize the loan for 20 years,” said Michell. “It doesn’t make any sense.”
The Kanaka Band has already invested $450,000 in feasibility, hydrology and engineering studies, with a similar investment from Green Valley.
B.C. Hydro announced it would pursue five purchase agreements last March with five First Nations projects — including Siwash Creek — including hydro, solar and wind energy projects, as two new generating stations were being commissioned at the time. A purchase agreement allows proponents to sell electricity to B.C. Hydro at a set price.
However, at least ten other “shovel-ready” clean energy projects may be doomed while B.C. Hydro completes a review of its own operations and its place in the energy sector, where legal outcomes like the Squamish power project ruling add uncertainty, including B.C.’s future power needs.
With the 1,100-megawatt Site C Dam planned for completion in 2024, and LNG demand cited to justify it, B.C. Hydro now projects it will have a surplus of electricity until the early 2030s.
Even if British Columbians put 300,000 electric vehicles on the road over the next 12 years, amid BC Hydro’s first call for power, they will require only 300 megawatts of new capacity, the company said.
A long-term surplus could effectively halt all small-scale clean energy development, according to Clean Energy B.C., even as Hydro One’s U.S. coal plant remains online in the region.
“(B.C. Hydro) dropped their offer down to 500 kilowatts right around the time they announced their review,” said Michell. “So we filled out the paperwork at 500 kilowatts and (B.C. Hydro) got to make its announcement of five projects.”
In the new few weeks, Kanaka and Green Valley will discuss whether they can move forward with a new financial model or shelve the project, he said.
B.C. Hydro declined to comment on the rationale for downsizing Siwash Creek’s power purchase agreement.
The Kanaka Bar Band successfully operates a 49.9-megawatt run-of-river plant on Kwoiek Creek with partners Innergex Renewable Energy.
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.
Nation Rise Wind Farm Ruling overturns Ontario cancellation, as Superior Court finds the minister's decision unreasonable; EDP Renewables restarts 100-megawatt project near Cornwall, citing jobs, clean energy, and procedural fairness over bat habitat concerns.
✅ EDP Renewables to restart construction near Cornwall
✅ 100 MW, 29 turbines; costs awarded, appeal considered
Construction of a wind farm in eastern Ontario, as wind power makes gains nationwide, will move ahead after a court quashed a provincial government decision to cancel the project.
In a ruling released Wednesday, a panel of Ontario Superior Court judges said the province's decision to scrap the Nation Rise Wind Farm in December 2019 did not meet the proper requirements.
At the time, Environment Minister Jeff Yurek revoked the approvals of the project near Cornwall, Ont., citing the risk to three bat species.
That decision came despite a ruling from the province's Environmental Review Tribunal that determined the risk the project posed to the bat population was negligible.
The judges said the minister's decision was "unreasonable" and "procedurally unfair."
"The decision does not meet requirements of transparency, justification, and intelligibility, as the Minister has failed to adequately explain his decision," the judges wrote in their decision.
The company behind the project, EDP Renewables, said the 29-turbine wind farm was almost complete when its approval was revoked in December, even as Alberta saw TransAlta scrap a wind farm in a separate development.
The company said Thursday it plans to restart construction on the 100-megawatt wind farm.
"EDPR is eager to recommence construction of the Nation Rise Wind Farm, which will bring much-needed jobs and investment to the community," the company said in a statement. "This delay has resulted in unnecessary expenditures to-date, at a time when governments and businesses should be focused on reducing costs and restarting the economy."
A spokesman for Yurek said the government is disappointed with the outcome of the case but did not comment on a possible appeal.
"At this time, we are reviewing the decision and are carefully considering our next steps," Andrew Buttigieg said in a statement.
NDP climate change critic Peter Tabuns said the court decision is an embarrassment for the minister and the government. He urged the government not to pursue an appeal.
Yurek "was found to have ignored the evidence and the facts," he said. "They didn't just lose, their case collapsed. They had nothing to stand on. Taking this to appeal would be a complete and total waste of money."
Green party Leader Mike Schreiner said the ruling proves the government was acting based on ideology over evidence when it revoked the project's approval.
"As we shift towards a post-COVID recovery, we need the Ford government to give up the irrational crusade against affordable and reliable clean energy," Schreiner said in a statement.
Last year, the NDP revealed the province had spent $231 million to cancel more than 750 renewable energy contracts, a move Ford said he was proud of, shortly after winning the 2018 election.
The Progressive Conservatives have blamed the previous Liberal government, as leadership candidates debate how to fix power, for signing the bad energy deals while the province had an oversupply of electricity.
The Ford government, amid a new stance on wind power, has also said that by cancelling the contracts it would ultimately save ratepayers $790 million -- a figure industry officials have disputed.
At the time of the wind farm cancellation, the government also said it would introduce legislation that would protect consumers from any costs incurred, though a developer warned cancellations could exceed $100M at the time.
It has since acknowledged it will have to pay some companies to cancel the deals and set aside $231 million to reach agreements with those firms, and more recently has moved to reintroduce renewable projects in some cases.
On Wednesday, the judges awarded Nation Rise $126,500 in costs, which the government will have to pay.
Nova Scotia Power Rate Increase Settlement faces UARB scrutiny as regulators weigh electricity rates, fuel costs, storm rider provisions, Bill 212 limits, and Muskrat Falls impacts on ratepayers and affordability for residential and industrial customers.
Key Points
A deal proposing 13.8% electricity hikes for 2023-2024, before the UARB, covering fuel costs, a storm rider, and Bill 212.
✅ UARB review may set different rates than the settlement
✅ Fuel cost prepayment and hedging incentives questioned
✅ Storm rider shifts climate risk onto ratepayers
Nova Scotia Premier Tim Houston is calling on provincial regulators to reject a settlement agreement between Nova Scotia Power and customer groups that would see electricity rates rise by nearly 14% electricity rate hike over the next two years.
"It is our shared responsibility to protect ratepayers and I can't state strongly enough how concerned I am that the agreement before you does not do that," Houston wrote in a letter to the Nova Scotia Utility and Review Board late Monday.
Houston urged the three-member panel to "set the agreement aside and reach its own conclusion on the aforementioned application."
"I do not believe, based on what I know, that the proposed agreement is in the best interest of ratepayers," he said.
The letter does not spell out what his Progressive Conservative government would do if the board accepts the settlement reached last week between Nova Scotia Power and lawyers representing residential, small business and large industrial customer classes.
Other groups also endorsed the deal, although Nova Scotia Power's biggest customer — Port Hawkesbury Paper — did not sign on.
'We're protecting the ratepayers' Natural Resources Minister Tory Rushton said the province was not part of the negotiations leading up to the settlement.
"As a government or department we had no intel on those conversations that were taking place," he said Tuesday. "So, we saw the information the same as the public did late last week, and right now we're protecting the ratepayers of Nova Scotia, even though the province cannot order Nova Scotia Power to lower rates under current law. We want to make sure that that voice is still heard at the UARB level."
Rushton said he didn't want to presuppose what the UARB will say.
"But I think the premier's been very loud and clear and I believe I have been, too. The ratepayers are at the top of our mind. We have different tools at our [disposal] and we'll certainly do what we can and need to [do] to protect those ratepayers."
The settlement agreement If approved by regulators, rates would rise by 6.9 per cent in 2023 and 6.9 per cent in 2024 — almost the same amount on the table when hearings before the review board ended in September.
The Houston government later intervened with legislation, known as Bill 212, that capped rates to cover non-fuel costs by 1.8 per cent. It did not cap rates to cover fuel costs or energy efficiency programs.
In a statement announcing the agreement, Nova Scotia Power president Peter Gregg claimed the settlement adhered "to the direction provided by the provincial government through Bill 212."
Consumer advocate Bill Mahody, representing residential customers, told CBC News the proposed 13.8 per cent increase was "a reasonable rate increase given the revenue requirement that was testified to at the hearing."
Settlement 'remarkably' similar to NSP application The premier disagrees, noting that the settlement and rate application that triggered the rate cap are "remarkably consistent."
He objects to the increased amount of fuel costs rolled into rates next year before the annual true up of actual fuel costs, which are automatically passed on to ratepayers.
"If Nova Scotia Power is effectively paid in advance, what motive do they have to hedge and mitigate the adjustment eventually required," Houston asked in his letter.
He also objected to the inclusion of a storm rider in rates to cover extreme weather, which he said pushed the risk of climate change on to ratepayers.
Premier second-guesses Muskrat Falls approval Houston also second-guessed the board for approving Nova Scotia Power's participation in the Muskrat Falls hydro project in Labrador.
"The fact that Nova Scotians have paid over $500 million for this project with minimal benefit, and no one has been held accountable, is wrong," he said. "It was this board of the day that approved the contracts and entered the final project into rates."
Although the Maritime Link was built on time and on budget by an affiliated company, only a fraction of Muskrat Falls hydro has been delivered because of ongoing problems in Newfoundland, including an 18% electricity rate hike deemed unacceptable by the province's consumer advocate.
"I find it remarkable that those contracts did not include different risk sharing mechanisms; they should have had provisions for issues in oversight of project management. Nevertheless, it was approved, and is causing significant harm to ratepayers in the form of increased rates."
Houston notes that because of non-delivery from Muskrat Falls, Nova Scotia Power has been forced to buy much more expensive coal to burn to generate electricity.
Opposition reaction Opposition parties in Nova Scotia reacted to Houston's letter.
NDP Leader Claudia Chender dismissed it as bluster.
"It exposes his Bill 212 as not really helping Nova Scotians in the way that he said it would," she said. "Nothing in the settlement agreement contravenes that bill. But it seems that he's upset that he's been found out. And so here we are with another intervention in an independent regulatory body."
Liberal Leader Zach Churchill said the government should intervene to help ratepayers directly.
"We just think that it makes more sense to do that directly by supporting ratepayers through heating assistance, lump-sum electricity credits, rebate programs and expanding the eligibility for that or to provide funding directly to ratepayers instead of intervening in the energy market in this way," he said.
The premier's office said that no one was available when asked about an interview on Tuesday.
"The letter speaks for itself," the office responded.
Nova Scotia Power issued a statement Tuesday. It did not directly address Houston's claims.
"The settlement agreement is now with the NS Utility and Review Board," the utility said.
"The UARB process is designed to ensure customers are represented with strong advocates and independent oversight. The UARB will determine whether the settlement results in just and reasonable rates and is in the public interest."
U.S. Tariffs on Chinese EVs and Solar Cells target trade imbalances, subsidies, and intellectual property risks, bolstering domestic manufacturing, supply chains, and national security across clean energy, automotive technology, and renewable markets.
Key Points
Policy measures raising duties on Chinese EVs and solar cells to protect U.S. industry, IP, and national security.
✅ Raises duties to counter subsidies and IP risks
✅ Supports domestic EV and solar manufacturing jobs
✅ May reshape supply chains, prices, and trade flows
In a significant move aimed at bolstering domestic industries and addressing trade imbalances, the Biden administration has announced higher tariffs on Chinese-made electric cars and solar cells. This decision marks a strategic shift in U.S. trade policy, with market observers noting EV tariffs alongside industrial and financial implications across sectors today.
Tariffs on Electric Cars
The imposition of tariffs on Chinese electric cars comes amidst growing competition in the global electric vehicle (EV) market. U.S. automakers and policymakers have raised concerns about unfair trade practices, subsidies, and market access barriers faced by American EV manufacturers in China amid escalating trade tensions with key partners. The tariffs aim to level the playing field and protect U.S. interests in the burgeoning electric vehicle sector.
Impact on Solar Cells
Similarly, higher tariffs on Chinese solar cells address concerns regarding intellectual property theft, subsidies, and market distortions in the solar energy industry, where tariff threats have influenced investment signals across North American markets.
The U.S. solar sector, a key player in renewable energy development, has called for measures to safeguard fair competition and promote domestic manufacturing of solar technologies.
Economic and Political Implications
The tariff hikes underscore broader economic tensions between the United States and China, spanning trade, technology, and geopolitical issues. While aimed at protecting American industries, these tariffs could lead to retaliatory measures from China and impact global supply chains, particularly in renewable energy and automotive sectors, as North American electricity exports at risk add to uncertainty across markets.
Industry and Market Responses
Industry stakeholders have responded with mixed reactions to the tariff announcements. U.S. automakers and solar manufacturers supportive of the tariffs argue they will help level the playing field and encourage domestic production. However, critics warn of potential energy price spikes for consumers, supply chain disruptions, and unintended consequences for global clean energy goals.
Strategic Considerations
The Biden administration's tariff policy reflects a broader strategy to promote economic resilience, innovation, and national security in critical industries, even as cross-border electricity exports become flashpoints in trade policy debates today.
Efforts to strengthen domestic supply chains, invest in renewable energy infrastructure, and foster international partnerships remain central to U.S. economic competitiveness and climate objectives.
Future Outlook
Looking ahead, navigating U.S.-China trade relations will continue to be a complex challenge for policymakers. Balancing economic interests, diplomatic engagements, and environmental priorities, alongside regional public support for tariffs, will shape future trade policy decisions affecting electric vehicles, renewable energy, and technology sectors globally.
Conclusion
The Biden administration's decision to impose higher tariffs on Chinese electric cars and solar cells represents a strategic response to economic and geopolitical dynamics reshaping global markets. While aimed at protecting American industries and promoting fair trade practices, the tariffs signal a commitment to fostering competitiveness, innovation, and sustainability in critical sectors of the economy. As these measures unfold, stakeholders will monitor their impact on industry dynamics, supply chain resilience, and international trade relations in the evolving landscape of global commerce.
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.
