"Wind for export" and carbon emissions regulations are fast becoming the hot topics in the energy industry, according to Ron Asche, Nebraska Public Power District (NPPD) president/CEO.
Asche addressed the Loup Power District Board of Directors telling them the most likely outcome of the industry-wide discussion would be to avoid jeopardizing the reliability of the energy grid and controlling rates for the customer.
"Wind for export and carbon emission regulations are certainly the two most important issues facing the power industry today," Asche said. "For the idea of wind for export to happen, there is going to have to be a fundamental policy change in public power. In 2008, the NPPD board adopted a 'slow go' approach that aims at 10 percent generation from renewables by 2020."
He said last year the statewide electric utility's generation resources were made up of just more than 1 percent from wind power, nearly 55 percent from coal, 32.8 percent from nuclear, 5 percent from gas and oil, 2.5 percent from hydro, and the remaining 6 percent from Western Area Power Association (WAPA) purchases.
Asche discussed challenges that face the public power industry from the current push toward wind for export.
"Policy considerations include public power's legal and statutory issues, location of wind farms, transmission planning, financials and cost recovery, and whether there even is an out-of-state market for wind energy," Asche said.
He said the current public power model is based on the concept that power generated is for Nebraska customers with any excess power then made available for sale to other markets. Under the "wind for export" model, power would be generated for the sole purpose of selling it outside the state.
"This is a great idea for economic development," Asche said. "But the challenges of reliability and transmission immediately come to mind when you may have contracts to meet and you're depending on an uncertain and intermittent generation source to generate power to fulfill those contracts."
Asche said the questions don't stop there. He told the directors that at this point there is no way to even estimate what the out-of-state market for wind energy may be. In addition he said the size and location of potential wind farms is going to be key to planning for transmission of the power generated.
Asche also identified the following as important:
• what are the environmental or land use issues that may affect where a wind farm can be?
• should wind farms be concentrated in one area to maximize ease of transmission or should they be dispersed across the state to enhance the potential economic benefits to a greater number of communities?
Asche said transmission planning is a real and challenging concern. He said he believes if national renewable goals are to be met, a national energy transmission plan will have to be designed and implemented.
"Finally, how is this going to be financed, and who will be ultimately responsible for the debt incurred in the development of this system," Asche asked. "Will Nebraska ratepayers be asked to guarantee the debt, or will capital be available to private developers?
"I think the federal government is going to have to be involved in providing government financing if the renewable energy goals are to be met in a similar way that the government was responsible for financing the nation's interstate highway system.
"There are a lot of issues here, and it's going to take time to work it all out. In spite of impatience on the part of some policymakers, this won't happen overnight — it can't happen that way."
The second part of Asche's presentation to the directors had to do with the potential effect carbon reduction legislation could have on Nebraska's utilities if it is passed.
"One of President Obama's campaign goals was for the reduction of carbon emissions to 1990 levels by 2020 and for a reduction in carbon emissions to be 80 percent below 1990 levels by 2050," Asche said.
Asche said today, 60 percent of NPPD's total generation resources come from carbon emitting resources. He told the directors that the utility's emissions in 2008 were about 10.6 million metric tons. To reduce that to 1990 levels, an approximate 40 percent reduction, would require bringing the levels down to 6.3 million metric tons and by 2050 to just 1.3 million metric tons to reach the 80 percent below 1990 levels.
He said current discussions most often do not acknowledge the probability of increases in the energy load or use of consumers. He said the approximate 40 percent increase from 1990 levels of carbon emissions to the current levels is consistent with energy load growth in the same time period.
Asche said before "wind for export" can be a viable option for economic development, wind and other renewables or increased nuclear power would first have to replace the reduction in carbon based generation sources.
"How do we get to 1990 levels by 2020? The only way would be to reduce NPPD's coal fired generation, reduce non-firm energy sales (sales to out-state customers), significantly increase wind generation and customers' energy efficiency practices and increase the energy output of the nuclear generation plant," Asche said.
Asche said the utility would have to increase wind generation to 20 percent of the generation resources by 2020 but that wind is an intermittent and essentially unreliable power generation source.
"Integrating wind power into the generation resource mix presents huge challenges to reliability," Asche said. "We may be able to meet the 2020 carbon emission reduction goals set by the president, but not without huge challenges to overcome.
"In the long term to meet the 2050 goals there will have to be more nuclear power or clean coal technologies in the mix and for that to work there would have to be virtually no opposition to building new nuclear plants."
Asche said a 20 to 30 percent increase in the cost of energy to the rate payers might be on the low end of costs to meet the possible outcomes of the legislation being proposed. He said when you add in the potential for additional carbon reduction taxes customers could see their rates double or triple.
"It's all very speculative at this time," Asche said. "But I believe these mandates will have huge impacts on low and moderate income families, and it could very well make us non competitive in the rest of the world."
California Wildfire Power Shut-Offs escalate as PG&E imposes blackouts amid high winds, Getty and Kincade fires, mass evacuations, Sonoma County threats, and a state of emergency, drawing regulatory scrutiny over grid safety and outage scope.
Key Points
Planned utility outages to curb wildfire risk during extreme winds, prompting evacuations and regulatory scrutiny.
✅ PG&E preemptive blackouts under regulator inquiry
✅ Getty and Kincade fires drive mass evacuations
✅ Sonoma County under threat amid high winds
Pacific Gas & Electric (PG&E) already faces an investigation by regulators after cutting supplies to 970,000 homes and businesses amid California blackouts that raised concerns.
It announced that another 650,000 properties would face precautionary shut-offs.
Wildfires fanned by the strong winds are raging in two parts of the state.
Thousands of residents near the wealthy Brentwood neighbourhood of Los Angeles have been told to evacuate because of a wildfire that began early on Monday.
Further north in Sonoma County, a larger fire has forced 180,000 people from their homes.
California's governor has declared a state-wide emergency.
What about the power cuts?
On Monday regulators announced a formal inquiry into whether energy utilities broke rules by pre-emptively cutting power to an estimated 2.5 million people, amid a blackouts policy debate that intensified, as wildfire risks soared.
They did not name any utilities but analysts said PG&E was responsible for the bulk of the "public safety power shut-offs", and later faced a Camp Fire guilty plea that underscored its liabilities.
The company filed for bankruptcy in January after facing hundreds of lawsuits from victims of wildfires in 2017 and 2018.
Of the 970,000 properties hit by the most recent cuts, under half had their services back by Monday, and some sought help through wildfire assistance programs, the Associated Press reported.
Despite criticism that the precautionary blackouts were too widespread and too disruptive, PG&E said more would come on Tuesday and Wednesday because further strong winds were expected.
The company said it had logged more than 20 preliminary reports of damage to its network from the most recent windstorm.
In a video posted to Twitter on Saturday, Governor Gavin Newsom said the power cuts were "infuriating everyone, and rightfully so".
Where are the fires now?
In Los Angeles, the Getty Fire has burned over 600 acres (242 ha) and about 10,000 buildings are in the mandatory evacuation zone.
At least eight homes have been destroyed and five others damaged.
"If you are in an evacuation zone, don't screw around," Mr Schwarzenegger tweeted. "Get out."
LA fire chief Ralph Terrazas said fire crews had been "overwhelmed" by the scale of the fires.
"They had to make some tough decisions on which houses they were able to protect," he said.
"Many times it depends on where the ember lands. I saw homes that were adjacent to homes that were totally destroyed, without any damage."
In northern California, schools remain closed in Sonoma County, where tens of thousands of homes and businesses are under threat.
Sonoma has been ravaged by the Kincade Fire, which started on Wednesday and has burned through 50,000 acres of land, fanned by the winds.
The Kincade Fire began seven minutes after a nearby power line was damaged, and power lines may have started fires according to reports, but PG&E has not yet confirmed if the power glitch started the blaze.
About 180,000 people have been ordered to evacuate, with roads around Santa Rosa north of San Francisco packed with cars as people tried to flee.
There are fears the flames could cross the 101 highway and enter areas that have not seen wildfires since the 1940s.
Australia-PNG Infrastructure Rollout delivers electricity and broadband expansion across PNG, backed by New Zealand, the US, Japan, and South Korea, enhancing telecom capacity, digital connectivity, and regional development ahead of the APEC summit.
Key Points
A multi-billion-dollar plan to expand power and broadband in PNG, covering 70% of users with allied support.
✅ Delivers internet to 70% of PNG households and communities
✅ Expands electricity grid, boosting reliability and access
✅ Backed by NZ, US, Japan, and S. Korea; complements APEC investments
Australia will lead a new multi-billion-dollar electricity and internet rollout in Papua New Guinea, with the PM rules out taxpayer-funded power plants stance underscoring its approach to energy policy.
The Australian newspaper reported New Zealand, the US, Japan, whose utilities' offshore wind deal in the UK signaled expanding energy interests, and South Korea are supporting the project, which will be PNG's largest ever development investment.
The project will deliver internet to 70 percent of PNG and improve access to power, even as clean energy investment in developing nations has slipped sharply, according to a recent report.
Both China and the US are also expected to announce new investments in the region at the APEC summit this week, and recent China-Cambodia nuclear energy cooperation underscores those energy ties.
Beijing will announce new mining and energy investments in PNG, echoing projects such as the Chinese-built electricity poles plant in South Sudan, and two Confucius Insitutes to be housed at PNG universities.
PG&E Wind Shutdown and Renewable Reliability examines PSPS strategy, wildfire risk, transmission line exposure, wind turbine cut-out speeds, grid stability, and California's energy mix amid historic high-wind events and supply constraints across service areas.
Key Points
An overview of PG&E's PSPS decisions, wildfire mitigation, and how wind cut-out limits influence grid reliability.
✅ Wind turbines reach cut-out near 55 mph, reducing generation.
✅ PSPS mitigates ignition from damaged transmission infrastructure.
✅ Baseload diversity improves resilience during high-wind events.
According to the official, widely reported story, Pacific Gas & Electric (PG&E) initiated power shutoffs across substantial portions of its electric transmission system in northern California as a precautionary measure.
Citing high wind speeds they described as “historic,” the utility claims that if it didn’t turn off the grid, wind-caused damage to its infrastructure could start more wildfires.
Perhaps that’s true. Perhaps. This tale presumes that the folks who designed and maintain PG&E’s transmission system are unaware of or ignored the need to design it to withstand severe weather events, and that the Federal Energy Regulatory Commission (FERC) and North American Electric Reliability Corp. (NERC) allowed the utility to do so.
Ignorance and incompetence happens, to be sure, but there’s much about this story that doesn’t smell right—and it’s disappointing that most journalists and elected officials are apparently accepting it without question.
Take, for example, this statement from a Fox News story about the Kincade Fires: “A PG&E meteorologist said it’s ‘likely that many trees will fall, branches will break,’ which could damage utility infrastructure and start a fire.”
Did you ever notice how utilities cut wide swaths of trees away when transmission lines pass through forests? There’s a reason for that: When trees fall and branches break, the grid can still function, and even as the electric rhythms of New York City shifted during COVID-19, operators planned for variability.
So, if badly designed and poorly maintained infrastructure isn’t the reason PG&E cut power to millions of Californians, what might have prompted them to do so? Could it be that PG&E’s heavy reliance on renewable energy means they don’t have the power to send when a “historic” weather event occurs, especially as policymakers weigh the postponed closure of three power plants elsewhere in California?
Wind Speed Limits
The two most popular forms of renewable energy come with operating limitations, which is why some energy leaders urge us to keep electricity options open when planning the grid. With solar power, the constraint is obvious: the availability of sunlight. One doesn’t generate solar power at night and energy generation drops off with increasing degrees of cloud cover during the day.
The main operating constraint of wind power is, of course, wind speed, and even in markets undergoing 'transformative change' in wind generation, operators adhere to these technical limits. At the low end of the scale, you need about a 6 or 7 miles-per-hour wind to get a turbine moving. This is called the “cut-in speed.” To generate maximum power, about a 30 mph wind is typically required. But, if the wind speed is too high, the wind turbine will shut down. This is called the “cut-out speed,” and it’s about 55 miles per hour for most modern wind turbines.
It may seem odd that wind turbines have a cut-out speed, but there’s a very good reason for it. Each wind turbine rotor is connected to an electric generator housed in the turbine nacelle. The connection is made through a gearbox that is sized to turn the generator at the precise speed required to produce 60 Hertz AC power.
The blades of the wind turbine are airfoils, just like the wings of an airplane. Adjusting the pitch (angle) of the blades allows the rotor to maintain constant speed, which, in turn, allows the generator to maintain the constant speed it needs to safely deliver power to the grid. However, there’s a limit to blade pitch adjustment. When the wind is blowing so hard that pitch adjustment is no longer possible, the turbine shuts down. That’s the cut-out speed.
Now consider how California’s power generation profile has changed. According to Energy Information Administration data, the state generated 74.3 percent of its electricity from traditional sources—fossil fuels and nuclear, amid debates over whether to classify nuclear as renewable—in 2001. Hydroelectric, geothermal, and biomass-generated power accounted for most of the remaining 25.7 percent, with wind and solar providing only 1.98 percent of the total.
By 2018, the state’s renewable portfolio had jumped to 43.8 percent of total generation, with clean power increasing and wind and solar now accounting for 17.9 percent of total generation. That’s a lot of power to depend on from inherently unreliable sources. Thus, it wouldn’t be at all surprising to learn that PG&E didn’t stop delivering power out of fear of starting fires, but because it knew it wouldn’t have power to deliver once high winds shut down all those wind turbines
Rising Greenhouse Gas Concentrations drive climate change, with CO2, methane, and nitrous oxide surging; WMO data show higher radiative forcing, elevated pre-industrial baselines, and persistent atmospheric concentrations despite Paris Agreement emissions pledges.
Key Points
Increasing atmospheric CO2, methane, and nitrous oxide levels that raise radiative forcing and drive warming.
✅ WMO data show CO2 at 407.8 ppm in 2018, above decade average
✅ Methane and nitrous oxide surged, elevating total radiative forcing
✅ Concentrations differ from emissions; sinks absorb about half
The World Meteorological Organization (WMO) says the increase in CO2 was just above the average rise recorded over the last decade.
Levels of other warming gases, such as methane and nitrous oxide, have also surged by above average amounts.
Since 1990 there's been an increase of 43% in the warming effect on the climate of long lived greenhouse gases.
The WMO report looks at concentrations of warming gases in the atmosphere rather than just emissions.
The difference between the two is that emissions refer to the amount of gases that go up into the atmosphere from the use of fossil fuels, such as burning coal for coal-fired electricity generation and from deforestation.
Concentrations are what's left in the air after a complex series of interactions between the atmosphere, the oceans, the forests and the land. About a quarter of all carbon emissions are absorbed by the seas, and a similar amount by land and trees, while technologies like carbon capture are being explored to remove CO2.
Using data from monitoring stations in the Arctic and all over the world, researchers say that in 2018 concentrations of CO2 reached 407.8 parts per million (ppm), up from 405.5ppm a year previously.
This increase was above the average for the last 10 years and is 147% of the "pre-industrial" level in 1750.
The WMO also records concentrations of other warming gases, including methane and nitrous oxide, and some countries have reported declines in certain potent gases, as noted in US greenhouse gas controls reports, though global levels remain elevated. About 40% of the methane emitted into the air comes from natural sources, such as wetlands, with 60% from human activities, including cattle farming, rice cultivation and landfill dumps.
Methane is now at 259% of the pre-industrial level and the increase seen over the past year was higher than both the previous annual rate and the average over the past 10 years.
Nitrous oxide is emitted from natural and human sources, including from the oceans and from fertiliser-use in farming. According to the WMO, it is now at 123% of the levels that existed in 1750.
Last year's increase in concentrations of the gas, which can also harm the ozone layer, was bigger than the previous 12 months and higher than the average of the past decade.
What concerns scientists is the overall warming impact of all these increasing concentrations. Known as total radiative forcing, this effect has increased by 43% since 1990, and is not showing any indication of stopping.
There is no sign of a slowdown, let alone a decline, in greenhouse gases concentration in the atmosphere despite all the commitments under the Paris agreement on climate change and the ongoing global energy transition efforts," said WMO Secretary-General Petteri Taalas.
"We need to translate the commitments into action and increase the level of ambition for the sake of the future welfare of mankind," he added.
"It is worth recalling that the last time the Earth experienced a comparable concentration of CO2 was three to five million years ago. Back then, the temperature was 2-3C warmer, sea level was 10-20m higher than now," said Mr Taalas.
The UN Environment Programme will report shortly on the gap between what actions countries are taking to cut carbon, for example where Australia's emissions rose 2% recently, and what needs to be done to keep under the temperature targets agreed in the Paris climate pact.
Preliminary findings from this study, published during the UN Secretary General's special climate summit last September, indicated that emissions continued to rise during 2018, although global emissions flatlined in 2019 according to the IEA.
Both reports will help inform delegates from almost 200 countries who will meet in Madrid next week for COP25, following COP24 in Katowice the previous year, the annual round of international climate talks.
UK Electricity Grid Investment underpins net zero, reinforcing transmission and distribution networks to integrate wind, solar, EV charging, and heat pumps, while Ofgem balances investor returns, debt risks, price controls, resilience, and consumer bills.
Key Points
Capital to reinforce grids for net zero, integrating wind, solar, EVs and heat pumps while balancing returns and bills.
✅ 170bn-210bn GBP by 2050 to reinforce cables, pylons, capacity.
✅ Ofgem to add investability metric while protecting consumers.
Prime Minister Sunak's recent upgrade to his home's electricity grid, designed to power his heated swimming pool, serves as a microcosm of a much larger challenge facing the UK: transforming the nation's entire electricity network for net zero emissions, amid Europe's electrification push across the continent.
This transition requires a monumental £170bn-£210bn investment by 2050, earmarked for reinforcing and expanding onshore cables and pylons that deliver electricity from power stations to homes and businesses. This overhaul is crucial to accommodate the planned switch from fossil fuels to clean energy sources - wind and solar farms - powering homes with electric cars, as EV demand on the grid rises, and heat pumps.
The UK government's Climate Change Committee warns of potentially doubled electricity demand by 2050, the target date for net zero, even though managing EV charging can ease local peaks. This translates to a significant financial burden for companies like National Grid, SSE, and Scottish Power who own the main transmission networks and some regional distribution networks.
Balancing investor needs for returns and ensuring affordable energy bills for consumers presents a delicate tightrope act for regulators like Ofgem. The National Audit Office criticized Ofgem in 2020 for allowing network owners excessive returns, prompting concerns about potential bill hikes, especially after lessons from 2021 reshaped market dynamics.
Think-tank Common Wealth reported that distribution networks paid out a staggering £3.6bn to their owners between 2017 and 2021, raising questions about the balance between profitability and affordability, amid UK EV affordability concerns among consumers.
However, Ofgem acknowledges the need for substantial investment to finance network upgrades, repairs, and the clean energy transition. To this end, they are considering incorporating an "investability" metric, recognizing how big battery rule changes can erode confidence elsewhere, in the next price controls for transmission networks, ensuring these entities remain attractive for equity fundraising without overburdening consumers.
This proposal, while welcomed by the industry, has drawn criticism from consumer advocacy groups like Citizens Advice, who fear it could contribute to unfairly high bills. With energy bills already hitting record highs, public trust in the net-zero transition hinges on ensuring affordability.
High debt levels and potential credit rating downgrades further complicate the picture, potentially impacting companies' ability to raise investment funds. Ofgem is exploring measures to address this, such as stricter debt structure reporting requirements for regional distribution companies.
Lawrence Slade, CEO of the Energy Networks Association, emphasizes the critical role of investment in achieving net zero. He highlights the need for "bold" policies and regulations that balance ambitious goals with investor confidence and ensure efficient resource allocation, drawing on B.C.'s power supply challenges as a cautionary example.
The challenge lies in striking a delicate balance between attracting investment, ensuring network resilience, and maintaining affordable energy bills. As Andy Manning from Citizens Advice warns, "Without public confidence, net zero won't be delivered."
The UK's journey to net zero hinges on navigating this complex landscape. By carefully calibrating regulations, fostering investor confidence, and prioritizing affordability, the country can ensure its electricity grid is not just robust enough to power heated swimming pools, but also a thriving green economy for all.
Boeing 787 More-Electric Architecture replaces pneumatics with bleedless pressurization, VFSG starter-generators, electric brakes, and heated wing anti-ice, leveraging APU, RAT, batteries, and airport ground power for efficient, redundant electrical power distribution.
Key Points
An integrated, bleedless electrical system powering start, pressurization, brakes, and anti-ice via VFSGs, APU and RAT.
✅ VFSGs start engines, then generate 235Vac variable-frequency power
✅ Bleedless pressurization, electric anti-ice improve fuel efficiency
✅ Electric brakes cut hydraulic weight and simplify maintenance
The 787 Dreamliner is different to most commercial aircraft flying the skies today. On the surface it may seem pretty similar to the likes of the 777 and A350, but get under the skin and it’s a whole different aircraft.
When Boeing designed the 787, in order to make it as fuel efficient as possible, it had to completely shake up the way some of the normal aircraft systems operated. Traditionally, systems such as the pressurization, engine start and wing anti-ice were powered by pneumatics. The wheel brakes were powered by the hydraulics. These essential systems required a lot of physical architecture and with that comes weight and maintenance. This got engineers thinking.
What if the brakes didn’t need the hydraulics? What if the engines could be started without the pneumatic system? What if the pressurisation system didn’t need bleed air from the engines? Imagine if all these systems could be powered electrically… so that’s what they did.
Power sources
The 787 uses a lot of electricity. Therefore, to keep up with the demand, it has a number of sources of power, much as grid operators track supply on the GB energy dashboard to balance loads. Depending on whether the aircraft is on the ground with its engines off or in the air with both engines running, different combinations of the power sources are used.
Engine starter/generators
The main source of power comes from four 235Vac variable frequency engine starter/generators (VFSGs). There are two of these in each engine. These function as electrically powered starter motors for the engine start, and once the engine is running, then act as engine driven generators.
The generators in the left engine are designated as L1 and L2, the two in the right engine are R1 and R2. They are connected to their respective engine gearbox to generate electrical power directly proportional to the engine speed. With the engines running, the generators provide electrical power to all the aircraft systems.
APU starter/generators
In the tail of most commercial aircraft sits a small engine, the Auxiliary Power Unit (APU). While this does not provide any power for aircraft propulsion, it does provide electrics for when the engines are not running.
The APU of the 787 has the same generators as each of the engines — two 235Vac VFSGs, designated L and R. They act as starter motors to get the APU going and once running, then act as generators. The power generated is once again directly proportional to the APU speed.
The APU not only provides power to the aircraft on the ground when the engines are switched off, but it can also provide power in flight should there be a problem with one of the engine generators.
Battery power
The aircraft has one main battery and one APU battery. The latter is quite basic, providing power to start the APU and for some of the external aircraft lighting.
The main battery is there to power the aircraft up when everything has been switched off and also in cases of extreme electrical failure in flight, and in the grid context, alternatives such as gravity power storage are being explored for long-duration resilience. It provides power to start the APU, acts as a back-up for the brakes and also feeds the captain’s flight instruments until the Ram Air Turbine deploys.
Ram air turbine (RAT) generator
When you need this, you’re really not having a great day. The RAT is a small propeller which automatically drops out of the underside of the aircraft in the event of a double engine failure (or when all three hydraulics system pressures are low). It can also be deployed manually by pressing a switch in the flight deck.
Once deployed into the airflow, the RAT spins up and turns the RAT generator. This provides enough electrical power to operate the captain’s flight instruments and other essentials items for communication, navigation and flight controls.
External power
Using the APU on the ground for electrics is fine, but they do tend to be quite noisy. Not great for airports wishing to keep their noise footprint down. To enable aircraft to be powered without the APU, most big airports will have a ground power system drawing from national grids, including output from facilities such as Barakah Unit 1 as part of the mix. Large cables from the airport power supply connect 115Vac to the aircraft and allow pilots to shut down the APU. This not only keeps the noise down but also saves on the fuel which the APU would use.
The 787 has three external power inputs — two at the front and one at the rear. The forward system is used to power systems required for ground operations such as lighting, cargo door operation and some cabin systems. If only one forward power source is connected, only very limited functions will be available.
The aft external power is only used when the ground power is required for engine start.
Circuit breakers
Most flight decks you visit will have the back wall covered in circuit breakers — CBs. If there is a problem with a system, the circuit breaker may “pop” to preserve the aircraft electrical system. If a particular system is not working, part of the engineers procedure may require them to pull and “collar” a CB — placing a small ring around the CB to stop it from being pushed back in. However, on the 787 there are no physical circuit breakers. You’ve guessed it, they’re electric.
Within the Multi Function Display screen is the Circuit Breaker Indication and Control (CBIC). From here, engineers and pilots are able to access all the “CBs” which would normally be on the back wall of the flight deck. If an operational procedure requires it, engineers are able to electrically pull and collar a CB giving the same result as a conventional CB.
Not only does this mean that the there are no physical CBs which may need replacing, it also creates space behind the flight deck which can be utilised for the galley area and cabin.
A normal flight
While it’s useful to have all these systems, they are never all used at the same time, and, as the power sector’s COVID-19 mitigation strategies showed, resilience planning matters across operations. Depending on the stage of the flight, different power sources will be used, sometimes in conjunction with others, to supply the required power.
On the ground
When we arrive at the aircraft, more often than not the aircraft is plugged into the external power with the APU off. Electricity is the blood of the 787 and it doesn’t like to be without a good supply constantly pumping through its system, and, as seen in NYC electric rhythms during COVID-19, demand patterns can shift quickly. Ground staff will connect two forward external power sources, as this enables us to operate the maximum number of systems as we prepare the aircraft for departure.
Whilst connected to the external source, there is not enough power to run the air conditioning system. As a result, whilst the APU is off, air conditioning is provided by Preconditioned Air (PCA) units on the ground. These connect to the aircraft by a pipe and pump cool air into the cabin to keep the temperature at a comfortable level.
APU start
As we near departure time, we need to start making some changes to the configuration of the electrical system. Before we can push back , the external power needs to be disconnected — the airports don’t take too kindly to us taking their cables with us — and since that supply ultimately comes from the grid, projects like the Bruce Power upgrade increase available capacity during peaks, but we need to generate our own power before we start the engines so to do this, we use the APU.
The APU, like any engine, takes a little time to start up, around 90 seconds or so. If you remember from before, the external power only supplies 115Vac whereas the two VFSGs in the APU each provide 235Vac. As a result, as soon as the APU is running, it automatically takes over the running of the electrical systems. The ground staff are then clear to disconnect the ground power.
If you read my article on how the 787 is pressurised, you’ll know that it’s powered by the electrical system. As soon as the APU is supplying the electricity, there is enough power to run the aircraft air conditioning. The PCA can then be removed.
Engine start
Once all doors and hatches are closed, external cables and pipes have been removed and the APU is running, we’re ready to push back from the gate and start our engines. Both engines are normally started at the same time, unless the outside air temperature is below 5°C.
On other aircraft types, the engines require high pressure air from the APU to turn the starter in the engine. This requires a lot of power from the APU and is also quite noisy. On the 787, the engine start is entirely electrical.
Power is drawn from the APU and feeds the VFSGs in the engines. If you remember from earlier, these fist act as starter motors. The starter motor starts the turn the turbines in the middle of the engine. These in turn start to turn the forward stages of the engine. Once there is enough airflow through the engine, and the fuel is igniting, there is enough energy to continue running itself.
After start
Once the engine is running, the VFSGs stop acting as starter motors and revert to acting as generators. As these generators are the preferred power source, they automatically take over the running of the electrical systems from the APU, which can then be switched off. The aircraft is now in the desired configuration for flight, with the 4 VFSGs in both engines providing all the power the aircraft needs.
As the aircraft moves away towards the runway, another electrically powered system is used — the brakes. On other aircraft types, the brakes are powered by the hydraulics system. This requires extra pipe work and the associated weight that goes with that. Hydraulically powered brake units can also be time consuming to replace.
By having electric brakes, the 787 is able to reduce the weight of the hydraulics system and it also makes it easier to change brake units. “Plug in and play” brakes are far quicker to change, keeping maintenance costs down and reducing flight delays.
In-flight
Another system which is powered electrically on the 787 is the anti-ice system. As aircraft fly though clouds in cold temperatures, ice can build up along the leading edge of the wing. As this reduces the efficiency of the the wing, we need to get rid of this.
Other aircraft types use hot air from the engines to melt it. On the 787, we have electrically powered pads along the leading edge which heat up to melt the ice.
Not only does this keep more power in the engines, but it also reduces the drag created as the hot air leaves the structure of the wing. A double win for fuel savings.
Once on the ground at the destination, it’s time to start thinking about the electrical configuration again. As we make our way to the gate, we start the APU in preparation for the engine shut down. However, because the engine generators have a high priority than the APU generators, the APU does not automatically take over. Instead, an indication on the EICAS shows APU RUNNING, to inform us that the APU is ready to take the electrical load.
Shutdown
With the park brake set, it’s time to shut the engines down. A final check that the APU is indeed running is made before moving the engine control switches to shut off. Plunging the cabin into darkness isn’t a smooth move. As the engines are shut down, the APU automatically takes over the power supply for the aircraft. Once the ground staff have connected the external power, we then have the option to also shut down the APU.
However, before doing this, we consider the cabin environment. If there is no PCA available and it’s hot outside, without the APU the cabin temperature will rise pretty quickly. In situations like this we’ll wait until all the passengers are off the aircraft until we shut down the APU.
Once on external power, the full flight cycle is complete. The aircraft can now be cleaned and catered, ready for the next crew to take over.
Bottom line
Electricity is a fundamental part of operating the 787. Even when there are no passengers on board, some power is required to keep the systems running, ready for the arrival of the next crew. As we prepare the aircraft for departure and start the engines, various methods of powering the aircraft are used.
The aircraft has six electrical generators, of which only four are used in normal flights. Should one fail, there are back-ups available. Should these back-ups fail, there are back-ups for the back-ups in the form of the battery. Should this back-up fail, there is yet another layer of contingency in the form of the RAT. A highly unlikely event.
The 787 was built around improving efficiency and lowering carbon emissions whilst ensuring unrivalled levels safety, and, in the wider energy landscape, perspectives like nuclear beyond electricity highlight complementary paths to decarbonization — a mission it’s able to achieve on hundreds of flights every single day.
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