Physicists have developed a way to turn heat into sound and then electricity, suggesting a new way to effectively recycle waste energy.
“We are converting waste heat to electricity in an efficient, simple way by using sound,” said the scientist who led the effort, Orest Symko of the University of Utah. “It is a new source of renewable energy from waste heat.”
Symko’s recycling devices are cylinder-shaped “resonators” that fit in the palm of your hand. Each cylinder contains a stack of material with a large surface area — such as metal or plastic plates, or fibers made of glass, cotton or steel wool — placed between cold and hot heat exchangers.
When heat is applied, the heat builds to a particular threshold where hot, moving air produces sound at a single frequency — like air blown into a flute.
“You have heat, which is so disorderly and chaotic, and all of a sudden you have sound coming out at one frequency,” Symko said.
The sound waves then squeeze what is called a piezoelectric device (“piezo” means pressure or squeezing). The pressure created produces an electric voltage. Symko says it is similar to when you hit your "funnybone" or the nerve on outside of your elbow, thereby generating that weird, painful pinch, which is actually an electrical nerve impulse.
Symko plans to test the devices within a year at a military radar facility and the University of UtahÂ’s hot-water-generating plant. (The U.S. Army funded the study in hopes the technology can be used to create a portable source of energy.)
Symko expects these devices could be used within two years as an alternative to the photovoltaic cells that currently convert sunlight into electricity, and could also provide a new way to cool laptops and other computers, and a to generate electricity from the heat released by nuclear power plant cooling towers.
Denmark Renewable Energy Outlook assesses Eurostat ranking, district heating and trash incineration, EV adoption, wind turbine testing expansions, and electrification to cut CO2, aligning policies with EU 2050 climate goals and green electricity usage.
Key Points
A brief analysis of Denmark's green power use, electrification, EVs, and policies needed to meet EU 2050 CO2 goals.
✅ Eurostat rank low due to trash incineration in district heating.
✅ EV adoption stalled after tax reinstatement, slowing electrification.
✅ Wind test centers expanded; electrification could cut 95% CO2.
Denmark’s low ranking in the latest figures from Eurostat regarding climate-friendly electricity, which places the country in 32nd place out of 40 countries, is partly a result of the country’s reliance on the incineration of trash to warm our homes via long-established district heating systems.
Additionally, there are not enough electric vehicles – a recent increase in sales was halted in 2016 when the government started to phase back registration taxes scrapped in 2008, and Europe’s EV slump underscores how fragile momentum can be.
Not enough green electricity being used
Denmark is good at producing green electricity, reports Politiken, but it does not use enough, and amid electricity price volatility in Europe this is bad news if it wants to fulfil the EU’s 2050 goal to eliminate CO2 emissions.
A recent report by Eurelectric and McKinsey demonstrates that if heating, transport and industry were electrified, reflecting a broader European push for electrification across the energy system, 95 percent of the country’s CO2 emissions could be eliminated by that date.
Wind turbine testing centre expansion approved
Parliament has approved the expansion of two wind turbine centres in northwest Jutland, supporting integration as e-mobility drives electricity demand in the coming years. The centres in Østerild and Høvsøre will have the capacity to test nine and seven turbines, measuring 330 and 200 metres in size (up from 250 and 165) respectively. The Østerild expansion should be completed in 2019, while Høvsøre will have to wait a little longer.
Third on the Environmental Performance Index
Denmark finished third on the latest Environmental Performance Index, finishing only behind Switzerland and France. Its best category ranking was third for Environmental Health, and comparative energy efficiency benchmarking can help contextualize progress. Elsewhere, it ranked 11th for Ecosystem Vitality, 18th for Biodiversity and Habitat, 94th for Forests, 87th for Fisheries, 25th for Climate and Energy and 37th for Air Pollution, 14th for Water Resources and 7th for Agriculture.
Texas EV Registration Fee adds a $200 annual charge under Senate Bill 505, offsetting lost gasoline tax revenue to the State Highway Fund, impacting electric vehicle owners at registration and renewals across Texas.
Key Points
A $200 yearly charge on electric vehicles to replace lost gasoline tax revenue and support Texas Highway Fund road work.
✅ $200 due at registration or renewal; $400 upfront on new EVs.
✅ Enacted by Senate Bill 505 to offset lost gasoline tax revenue.
Plano resident Tony Federico bought his Tesla five years ago in part because he hated spending lots of money on gas, and Supercharger billing changes have also influenced charging expenses. But that financial calculus will change slightly on Sept. 1, when Texas will start charging electric vehicle drivers an additional fee of $200 each year.
“It just seems like it’s arbitrary, with no real logic behind it,” said Federico, 51, who works in information technology. “But I’m going to have to pay it.”
Earlier this year, state lawmakers passed Senate Bill 505, which requires electric vehicle owners to pay the fee when they register a vehicle or renew their registration, even as fights for control over charging continue among utilities, automakers and retailers. It’s being imposed because lawmakers said EV drivers weren’t paying their fair share into a fund that helps cover road construction and repairs across Texas.
The cost will be especially high for those who purchase a new electric vehicle and have to pay two years of registration, or $400, up front.
Texas agencies estimated in a 2020 report that the state lost an average of $200 per year in federal and state gasoline tax dollars when an electric vehicle replaced a gas-fueled one. The agencies called the fee “the most straightforward” remedy.
Gasoline taxes go to the State Highway Fund, which the Texas Department of Transportation calls its “primary funding source.” Electric vehicle drivers don’t pay those taxes, though, because they don’t use gasoline.
Still, EV drivers do use the roads. And while electric vehicles make up a tiny portion of cars in Texas for now, that fraction is expected to increase, raising concerns about state power grids in the years ahead.
Many environmental and consumer advocates agreed with lawmakers that EV drivers should pay into the highway fund but argued over how much, and debates over fairer vehicle taxes are surfacing abroad as well.
Some thought the state should set the fee lower to cover only the lost state tax dollars, rather than both the state and federal money, because federal officials may devise their own scheme. Others argued the state should charge nothing because EVs help reduce greenhouse gas emissions that drive climate change and can offer budget benefits for many owners.
“We urgently need to get more electric vehicles on the road,” said Luke Metzger, executive director of Environment Texas. “Any increased fee could create an additional barrier for Texans, and particularly more moderate- to low-income Texans, to make that transition.”
Tom “Smitty” Smith, the executive director of the Texas Electric Transportation Resources Alliance, advocated for a fee based on how many miles a person drove their electric car, which would better mirror how the gas taxes are assessed.
Texas has a limited incentive that could offset the cost: It offers rebates of up to $2,500 for up to 2,000 new hydrogen fuel cell, electric or hybrid vehicles every two years. Adrian Shelley, Public Citizen’s Texas office director, recommended that the state expand the rebates, noting that state-level EV benefits can be significant.
In the Houston area, dealer Steven Wolf isn’t worried about the fee deterring potential customers from buying the electric Ford F-150 Lightning and Mustang Mach-E vehicles he sells. Electric cars are already more expensive than comparable gasoline-fueled cars, and charging networks compete for drivers, he said.
Germany Industrial Electricity Price Subsidy weighs subsidies for energy-intensive industries to bolster competitiveness as Germany shifts to renewables, expands grid capacity, and debates free-market tax cuts versus targeted relief and long-term policies.
Key Points
Policy to subsidize power for energy-intensive industry, preserving competitiveness during the energy transition.
✅ SPD backs 5-7 cents per kWh for 10-15 years
✅ FDP prefers tax cuts and free-market pricing
✅ Scholz urges cheap renewables and grid expansion first
Germany’s three-party coalition is debating whether electricity prices for energy-intensive industries should be subsidised in a market where rolling back European electricity prices can be tougher than it appears, to prevent companies from moving production abroad.
Calls to reduce the electricity bill for big industrial producers are being made by leading politicians, who, like others in Germany, fear the country could lose its position as an industrial powerhouse as it gradually shifts away from fossil fuel-based production, amid historic low energy demand and economic stagnation concerns.
“It is in the interest of all of us that this strong industry, which we undoubtedly have in Germany, is preserved,” Lars Klingbeil, head of Germany’s leading government party SPD (S&D), told Bayrischer Rundfunk on Wednesday.
To achieve this, Klingbeil is advocating a reduced electricity price for the industry of about 5 to 7 cents per Kilowatt hour, which the federal government would subsidise. This should be introduced within the next year and last for about 10 to 15 years, he said.
Under the current support scheme, which was financed as part of the €200 billion “rescue shield” against the energy crisis, energy-intensive industries already pay 13 cents per Kilowatt hour (KWh) for 70% of their previous electricity needs, which is substantially lower than the 30 to 40 cents per KWh that private consumers pay.
“We see that the Americans, for example, are spending $450 billion on the Inflation Reduction Act, and we see what China is doing in terms of economic policy,” Klingbeil said.
“If we find out in 10 years that we have let all the large industrial companies slip away because the investments are not being made here in Germany or Europe, and jobs and prosperity and growth are being lost here, then we will lose as a country,” he added.
However, not everyone in the German coalition favours subsidising electricity prices.
Finance Minister Christian Lindner of the liberal FDP (Renew), for example, has argued against such a step, instead promoting free-market principles and, amid rising household energy costs, reducing taxes on electricity for all.
“Privileging industrial companies would only be feasible at the expense of other electricity consumers and taxpayers, for example, private households or the small trade sector,” Lindner wrote in an op-ed for Handelsblatt on Tuesday.
“Increasing competitiveness for some would mean a loss of competitiveness for others,” he added.
Chancellor Olaf Scholz, himself a member of SPD, was more careful with his words, amid ongoing EU electricity reform debates in Brussels.
Asked about a subsidised electricity price for the industry at a town hall event on Monday, Scholz said he does not “want to make any promises now”.
“First of all, we have to make sure that we have cheap electricity in Germany in the first place,” Scholz said, promoting the expansion of renewable energy such as wind and solar, as local utilities cry for help, as well as more electricity grid infrastructure.
“What we will not be able to do as an economy, even as France’s new electricity pricing scheme advances, is to subsidise everything that takes place in normal economic activity,” Scholz said. “We should not get into the habit of doing that,” he added.
New York Renewable Energy Contracts secure 23 projects totaling 2.3 GW, spanning offshore wind, solar, and battery storage under CLCPA goals, advancing 70% by 2030, a carbon-free 2040 grid, grid reliability, and green jobs.
Key Points
State agreements securing 23 wind, solar, and storage projects (2.3 GW) to meet CLCPA clean power targets.
✅ 2.3 GW across 23 wind, solar, and storage projects statewide
✅ Supports 70% renewables by 2030; carbon-free grid by 2040
✅ Drives emissions cuts, grid reliability, and green jobs
In a significant milestone for the state’s clean energy ambitions, New York has finalized contracts with 23 renewable energy projects, as part of large-scale energy projects underway in New York, totaling a combined capacity of 2.3 gigawatts (GW). This move is part of the state’s ongoing efforts to accelerate its transition to renewable energy, reduce carbon emissions, and meet the ambitious targets set under the Climate Leadership and Community Protection Act (CLCPA), which aims to achieve a carbon-free electricity grid by 2040.
A Strong Commitment to Renewable Energy
The 23 projects secured under these contracts represent a diverse range of renewable energy sources, including wind, solar, and battery storage. Together, these projects are expected to contribute significantly to New York’s energy grid, generating enough clean electricity to power millions of homes. The deal is a key component of New York’s broader strategy to achieve a 70% renewable energy share in the state’s electricity mix by 2030 and to reduce greenhouse gas emissions by 85% by 2050.
Governor Kathy Hochul celebrated the agreements as a major step forward in the state’s commitment to combating climate change while creating green jobs and economic opportunities. “New York is leading the nation in its clean energy goals, and these projects will help us meet our bold climate targets while delivering reliable and affordable energy to New Yorkers,” Hochul said in a statement.
The Details of the Contracts
The 23 projects span across various regions of the state, with an emphasis on areas that are well-suited for renewable energy development, such as upstate New York, which boasts vast open spaces ideal for large-scale solar and wind installations and the state is investigating sites for offshore wind projects along the coast. The contracts finalized by the state will ensure a steady supply of clean power from these renewable sources, helping to stabilize the grid and reduce reliance on fossil fuels.
A significant portion of the new renewable capacity will come from offshore wind projects, which have become a cornerstone of New York’s renewable energy strategy. Offshore wind has the potential to provide large amounts of electricity, and the state recently greenlighted the country's biggest offshore wind farm to date, taking advantage of the state's proximity to the Atlantic Ocean. Several of the contracts finalized include offshore wind farm projects, which are expected to be operational within the next few years.
In addition to wind energy, solar power continues to be a critical component of the state’s renewable energy strategy. The state has already made substantial investments in solar energy, having achieved solar energy goals ahead of schedule recently, and these new contracts will further expand the state’s solar capacity. The inclusion of battery storage projects is another important element, as energy storage solutions are vital to ensuring that renewable energy can be effectively utilized, even when the sun isn’t shining or the wind isn’t blowing.
Economic and Job Creation Benefits
The finalization of these 23 contracts will not only bring significant environmental benefits but also create thousands of jobs in the renewable energy sector. Construction, maintenance, and operational jobs will be generated throughout the life of the projects, benefiting communities across the state, including areas near Long Island's South Shore wind proposals that stand to gain from new investment. The investment in renewable energy is expected to support New York’s recovery from the economic impacts of the COVID-19 pandemic, contributing to the state’s clean energy economy and providing long-term economic stability.
The state's focus on clean energy also provides opportunities for local businesses, highlighted by the first Clean Energy Community designation in the state, as many of these projects will require services and materials from within New York State. Additionally, Governor Hochul’s administration has made efforts to ensure that disadvantaged communities and workers from underrepresented backgrounds will have access to job training and employment opportunities within the renewable energy sector.
The Path Forward: A Clean Energy Future
New York’s aggressive move toward renewable energy is indicative of the state’s commitment to addressing climate change and leading the nation in clean energy innovation. By locking in contracts for these renewable energy projects, the state is not only securing a cleaner future but also ensuring that the transition is fair and just for all communities, particularly those that have been historically impacted by pollution and environmental degradation.
While the finalized contracts mark a major achievement, the state’s work is far from over. The completion of these 23 projects is just one piece of the puzzle in New York’s broader strategy to decarbonize its energy system. To meet its ambitious targets under the CLCPA, New York will need to continue investing in renewable energy, energy storage, grid modernization, and energy efficiency programs.
As New York moves forward with its clean energy transition, and as BOEM receives wind power lease requests in the Northeast, the state will likely continue to explore new technologies and innovative solutions to meet the growing demand for renewable energy. The success of the 23 finalized contracts serves as a reminder of the state’s leadership in the clean energy space and its ongoing efforts to create a sustainable, low-carbon future for all New Yorkers.
New York’s decision to finalize contracts with 23 renewable energy projects totaling 2.3 gigawatts represents a bold step toward meeting the state’s clean energy and climate goals. These projects, which include a mix of wind, solar, and energy storage, will contribute significantly to reducing the state’s reliance on fossil fuels and lowering greenhouse gas emissions. With the additional benefits of job creation and economic growth, this move positions New York as a leader in the nation’s transition to renewable energy and a sustainable future.
PG&E 2024 Rate Hikes signal sharp increases to fund wildfire safety, infrastructure upgrades, and CPUC-backed reliability, with rates expected to stabilize in 2025, affecting rural residents, businesses, and high-risk zones across California.
Key Points
PG&E’s 2024 hikes fund wildfire safety and grid upgrades, with pricing expected to stabilize in 2025.
✅ Driven by wildfire safety, infrastructure, and reinsurance costs
✅ Largest impacts in rural, high-risk zones; business rates vary
✅ CPUC oversight aims to ensure necessary, justified investments
Pacific Gas and Electric (PG&E) is expected to implement a series of rate hikes that, amid analyses of why California electricity prices are soaring across the state, will significantly impact California residents. These increases, while substantial, are anticipated to be followed by a period of stabilization in 2025, offering a sense of relief to customers facing rising costs.
PG&E, one of the largest utility providers in the state, announced that its 2024 rate hikes are part of efforts to address increasing operational costs, including those related to wildfire safety, infrastructure upgrades, and regulatory requirements. As California continues to face climate-related challenges like wildfires, utilities like PG&E are being forced to adjust their financial models to manage the evolving risks. Wildfire-related liabilities, which have plagued PG&E in recent years, play a significant role in these rate adjustments. In response to previous fire-related lawsuits, including a bankruptcy plan supported by wildfire victims that reshaped liabilities, and the increased cost of reinsurance, PG&E has made it clear that customers will bear part of the financial burden.
These rate hikes will have a multi-faceted impact. Residential users, particularly those in rural or high-risk wildfire zones, will see some of the largest increases. Business customers will also be affected, although the adjustments may vary depending on the size and energy consumption patterns of each business. PG&E has indicated that the increases are necessary to secure the utility’s financial stability while continuing to deliver reliable service to its customers.
Despite the steep increases in 2024, PG&E's executives have assured that the company's pricing structure will stabilize in 2025. The utility has taken steps to balance the financial needs of the business with the reality of consumer affordability. While some rate hikes are inevitable given California's regulatory landscape and climate concerns, PG&E's leadership believes the worst of the increases will be seen next year.
PG&E’s anticipated stabilization comes after a year of scrutiny from California regulators. The California Public Utilities Commission (CPUC) has been working closely with PG&E to scrutinize its rate request and ensure that hikes are justifiable and used for necessary investments in infrastructure and safety improvements. The CPUC’s oversight is especially crucial given the company’s history of safety violations and the public outrage over past wildfire incidents, including reports that its power lines may have sparked fires in California, which have been linked to PG&E’s equipment.
The hikes, though significant, reflect the broader pressures facing utilities in California, where extreme weather patterns are becoming more frequent and intense due to climate change. Wildfires, which have grown in severity and frequency in recent years, have forced PG&E to invest heavily in fire prevention and mitigation strategies, including compliance with a judge-ordered use of dividends for wildfire mitigation across its service area. This includes upgrading equipment, inspecting power lines, and implementing more rigorous protocols to prevent accidents that could spark devastating fires. These investments come at a steep cost, which PG&E is passing along to consumers through higher rates.
For homeowners and businesses, the potential for future rate stabilization offers a glimmer of hope. However, the 2024 increases are still expected to hit consumers hard, especially those already struggling with high living costs. The steep hikes have prompted public outcry, with calls for action as bills soar amplifying advocacy group arguments that utilities should absorb more of the costs related to climate change and fire prevention instead of relying on ratepayers.
Looking ahead to 2025, the expectation is that PG&E’s rates will stabilize, but the question remains whether they will return to pre-2024 levels or continue to rise at a slower rate. Experts note that California’s energy market remains volatile, and while the rates may stabilize in the short term, long-term cost management will depend on ongoing investments in renewable energy sources and continued efforts to make the grid more resilient to climate-related risks.
As PG&E navigates this challenging period, the company’s commitment to transparency and working with regulators will be crucial in rebuilding trust with its customers. While the immediate future may be financially painful for many, the hope is that the utility's focus on safety and infrastructure will lead to greater long-term stability and fewer dramatic rate increases in the years to come.
Ultimately, California residents will need to brace for another tough year in terms of utility costs but can find reassurance that PG&E’s rate increases will eventually stabilize. For those seeking relief, there are ongoing discussions about increasing energy efficiency, exploring renewable energy alternatives, and expanding assistance programs for lower-income households to help mitigate the financial strain of these price hikes.
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.
