Many of the people who played a role in hammering out a compromise between environmental groups and Xcel Energy had a chance to see the results of their labor, touring the Comanche Station power plant where work is under way on a 750-megawatt generator.
When the new unit is finished, Comanche will be Xcel's largest Colorado plant. The three members of Colorado's Public Utilities Commission - Ron Binz, Polly Page and Carl Miller - and more than 30 staff members from the PUC and the Office of Consumer Counsel traveled to Pueblo to tour the plant.
The group was about 45 minutes late because of a flat tire and at the beginning of a presentation by Xcel officials, Binz jokingly told the power company executives, "If you think you're having a bad day, how would you like to be the bus company, regulated by the PUC, that was supposed to get us here?"
In 2004, the PUC approved an agreement between Xcel and a number of groups including the Sierra Club and Better Pueblo, that provided for more strict pollution controls on the entire Pueblo plant along with efforts to mitigate other air quality issues in the area.
In return for Xcel's promises to improve the two existing 350-megawatt units here, the groups agreed not to fight approval by the PUC or the Colorado Department of Public Health and Environment, which had to issue an air permit.
The state officials saw at close hand the equipment being installed that will reduce sulfur dioxide and nitrogen oxide emissions at the plant to levels lower than they are now, even with the third unit running. New processes in the bag houses where exhaust is filtered also will reduce mercury emissions.
Tim Farmer, Comanche 3 project director, said that the new unit should be running by fall 2009.
The $1.3 billion project has provided hundreds of jobs for skilled union workers with $250 million of the total cost going to pay wages. Farmer said that employment should peak in February and March at 1,400 workers and then start to decline.
Bechtel is starting to recruit a similar work force for the mustard agent destruction program at the Pueblo Chemical Depot, but Farmer said that the Comanche work should be finishing up as Bechtel's project starts to grow. It hasn't been easy to find workers, he said. Pipefitters and boilermakers were in short supply, and 10-hour days Monday through Friday are the norm as the company tries to make do with overtime.
Farmer said workers are not asked to do longer shifts for safety reasons. Work is being done on all elements of the new unit, the boiler, turbine building and cooling towers, while other crews are retrofitting units 1 and 2 with the new pollution control equipment. Commodity prices also have gone up since work began, especially copper and aluminum, but much of what was needed was purchased early, he said.
The new plant will add about 40 jobs to Comanche's 137-person work force, and plant manager Frank Arellano said many have been brought in so they would be ready to go when the unit is finished.
The new generator will be more effective than the two already in operation, using supercritical water that can drive turbines at much greater efficiencies. The coal used will be ground to a finer powder to make it burn better.
Xcel, Farmer said, also is working to recycle the water it uses to cool its system. The company had to increase its contract with the Pueblo Board of Water Works to handle the needs of the third unit, but it also is installing new systems to reuse water that is now discharged into the St. Charles River.
American-Made Solar Prize Round 3 accelerates DOE-backed solar innovation, empowering entrepreneurs and domestic manufacturing with photovoltaics and grid integration support via National Laboratories, incubators, and investors to validate products, secure funding, and deploy backup power.
Key Points
A DOE challenge fast-tracking solar innovation to market readiness, boosting US manufacturing and grid integration.
✅ $50,000 awards to 20 teams for prototype validation
✅ Access to National Labs, incubators, investors, and mentors
✅ Focus on PV advances and grid integration solutions
The U.S. Department of Energy (DOE) announced the 20 competitors who have been invited to advance to the next phase of the American-Made Solar Prize Round 3, a competition designed to incentivize the nation’s entrepreneurs to strengthen American leadership in solar energy innovation and domestic manufacturing, a key front in the clean energy race today.
The American-Made Solar Prize is designed to help more American entrepreneurs thrive in the competitive global energy market. Each round of the prize brings new technologies to pre-commercial readiness in less than a year, ensuring new ideas enter the marketplace. As part of the competition, teams will have access to a network of DOE National Laboratories, technology incubators and accelerators, and related DOE efforts like next-generation building upgrades, venture capital firms, angel investors, and industry. This American-Made Network will help these competitors raise private funding, validate early-stage products, or test technologies in the field.
Each team will receive a $50,000 cash prize and become eligible to compete in the next phase of the competition. Through a rigorous evaluation process, teams were chosen based on the novelty of their ideas and how their solutions address a critical need of the solar industry. The teams were selected from 120 submissions and represent 11 states. These projects will tackle challenges related to new solar applications, like farming, as well as show how solar can be used to provide backup power when the grid goes down, aided by increasingly affordable batteries now reaching scale. Nine teams will advance solar photovoltaic technologies, and 11 will address challenges related to how solar integrates with the grid. The projects are as follows:
Photovoltaics:
Durable Antireflective and Self-Cleaning Glass (Pittsburgh, PA)
Pursuit Solar - More Power, Less Hassle (Denver, NC)
PV WaRD (San Diego, CA)
Remotely Deployed Solar Arrays (Charlottesville, VA)
Robotics Changing the Landscape for Solar Farms (San Antonio, TX)
TrackerSled (Chicago, IL)
Transparent Polymer Barrier Films for PV (Bristol, PA)
Solar for Snow (Duluth, MN)
SolarWall Power Tower (Buffalo, NY)
Systems Integration:
Affordable Local Solar Storage via Utility Virtual Power Plants (Parker, TX)
Allbrand Solar Monitor (Detroit, MI)
Beyond Monitoring – Next Gen Software and Hardware (Atlanta, GA)
Democratizing Solar with Artificial Intelligence Energy Management (Houston, TX)
Embedded, Multi-Function Maximum Power Point Tracker for Smart Modules (Las Vegas, NV)
Evergrid: Keep Solar Flowing When the Grid Is Down (Livermore, CA)
Inverter Health Scan (San Jose, CA)
JuiceBox: Integrated Solar Electricity for Americans Transitioning out of Homelessness and Recovering from Natural Disasters (Claremont, CA)
Low-Cost Parallel-Connected DC Power Optimizer (Blacksburg, VA)
Powerfly: A Plug-and-Play Solar Monitoring Device (Berkeley, CA)
Simple-Assembly Storage Kit (San Antonio, TX)
Read the descriptions of the projects to see how they contribute to efforts to improve solar and wind power worldwide.
Over the next six months, these teams will fast-track their efforts to identify, develop, and test disruptive solutions amid record solar and storage growth projected nationwide. During a national demonstration day at Solar Power International in September 2020, a panel of judges will select two final winners who will receive a $500,000 prize. Learn more at the American-Made Solar Prize webpage.
The American-Made Challenges incentivize the nation's entrepreneurs to strengthen American leadership in energy innovation and domestic manufacturing. These new challenges seek to lower the barriers U.S.-based innovators face in reaching manufacturing scale by accelerating the cycles of learning from years to weeks while helping to create partnerships that connect entrepreneurs to the private sector and the network of DOE’s National Laboratories across the nation, alongside recent wind energy awards that complement solar innovation.
Adams Nielson Solar Array, a 28 MW DC utility-scale project in Lind, WA, spans 200 acres with 81,700 panels, powering about 4,000 homes, supporting Avista’s Solar Select program and renewable energy, sustainability, and carbon reduction.
Key Points
Adams Nielson Solar Array is a 28 MW DC facility in Lind, WA, powering ~4,000 homes via Avista’s Solar Select.
✅ 81,700 panels across 200 acres in Eastern Washington
✅ Offsets emissions equal to removing 7,300 cars annually
✅ Collaboration by Avista, Strata Solar, WUTC, WSU Energy
Official commissioning of the Adams Nielson solar array located in Lind, WA occurred today. The 28 Megawatt DC array is comprised of 81,700 panels that span 200 acres and generates enough electricity to supply the equivalent of approximately 4,000 homes annually, similar to a new co-op solar project serving South Metro members.
“Avista’s interest in the development of Solar Select, a voluntary commercial solar program reflecting broader corporate adoption such as a corporate solar power plant commissioned by Arvato, is consistent with the Company’s ongoing commitment to provide customers with renewable energy choices at reasonable cost,” said Dennis Vermillion, president, Avista Corporation. “In recent years, an increasing number of Avista customers have expressed their expectations and challenges in acquiring renewable energy. Avista is pleased to lead this effort and develop renewable energy products that meet our customers’ needs today and into the future.” This interest is being generated by a mix of local and national customers across a variety of industries, including Huckleberry’s, Gonzaga University, Community Colleges of Spokane, Hotstart, Central Pre-Mix Concrete, a CRH Co., independently owned McDonald's franchise locations, Spokane City, Main Market and Community Building and VA Medical Center.
Jim Simon, director of sustainability at Gonzaga University said, “The Solar Select program helps Gonzaga University move even closer to achieving its goal of climate neutrality by 2050 by continuing to prioritize renewables in our energy portfolio, as other communities add projects like a municipal solar project to boost local supply. We are grateful for Avista’s leadership in this project and look forward to other opportunities to reduce our greenhouse gas emissions.”
Spokane Mayor David Condon said, “The City of Spokane is pleased to partner with Avista through the Solar Select Program, as we continue to seek out opportunities that are both environmentally and financially responsible. The City already is a net producer of energy, generating more clean, green energy than our use of electricity, natural gas, and fuel, a milestone also seen with North Carolina's first wind farm now fully operational. We are excited to add even more clean energy to power City Hall.”
The Solar Select program created a cost-effective structure to bring solar energy to large business customers in Eastern Washington, allowing them to advance their desired sustainability goals and benefiting from industry service innovations led by companies like Omnidian expanding their global reach. The array is projected to deliver the environmental benefit equivalent of more than 7,300 cars removed from the road each year. This renewable energy program was made possible through a collaboration of Avista, Strata Solar, the Washington Utilities and Transportation Commission, and the WSU Energy Program.
Gulf Power 40% One-Time Bill Decrease approved by the Florida Public Service Commission delivers a May fuel credit and COVID-19 relief, cutting residential and business costs across rate classes while supporting budgeting and energy savings.
Key Points
PSC-approved fuel credit cutting May electric bills about 40% for homes and 40-55% for businesses as COVID-19 relief.
✅ One-time May fuel credit on customer bills
✅ Residential cut ~40%; business savings 40-55% by rate class
✅ Online tools show daily usage and projected bill
Gulf Power announced that the Florida Public Service Commission unanimously approved its request to issue a one-time decrease of approximately 40% for the typical residential customer bill beginning May 1, similar to recent Georgia Power bill reductions seen elsewhere. Business customers will also see a significant one-time decrease of approximately 40-55% in May, depending on usage and rate class.
"We are pleased that the Florida Public Service Commission has approved our request to deliver this savings to our customers when they need it most. We felt that this was the right thing to do, especially during times like these," said Gulf Power President Marlene Santos. "Our customers and communities now more than ever count on the reliable and affordable energy we deliver, and we are pleased that May bills will reflect this additional, significant savings for our customers."
In Florida, fuel savings are typically refunded to customers over the remainder of the year to provide level, predictable bills. However, given the emergent and significant financial challenges facing many customers due to COVID-19, Gulf Power instead sought approval to give customers the total annual savings in their May bill, similar to a lump-sum electricity credit approach, which will be reflected as a line-item fuel credit on their May statement.
New tools to help save energy and money
Many customers are working from home and, in general, staying at home more. More time and extra people in the home will likely increase power usage, which could lead to higher monthly bills.
Gulf Power recently added new tools to our customers' online account portal to help them better understand and manage their energy usage, including their monthly projected bill amount and a breakdown of daily energy usage, which is available for most residential customers*. Customers can now see their previous day's energy usage using their online account portal to help them more easily understand how their previous day's activities impacted energy usage, allowing them to quickly make adjustments to keep bills low. The new projected bill feature is a valuable tool to assist customers in budgeting for their next month's energy bill.
Additional energy-saving tips that can be implemented with no additional cost or equipment are also available. As always, Gulf Power's free online Energy Checkup tool will provide customers with a customized report based on their home's actual energy use.
Helping customers pay their bills
Gulf Power has a long history of working with its customers during difficult times, including periods of pandemic-related energy insecurity, and will continue to do so. Gulf Power encourages customers that are having difficulty paying their energy bill to visit GulfPower.com/help to view available resources that can provide assistance to qualifying customers.
Customers are encouraged to pay their electric bill balance each month to avoid building up a large balance, which they will continue to bear responsibility for. Gulf Power will work with the customer's personal situation and assist with a solution, similar to how utilities in Texas have waived fees during this period, to help customers fulfill their personal responsibility for their Gulf Power balance.
Those who can afford or want to help others who may need assistance with their energy bill can make a donation to Project SHARE in your online customer portal. Project SHARE donations are added to a customer's monthly bill and all contributions are distributed to local offices of The Salvation Army. Customers in need of utility bill assistance can apply for Project SHARE assistance at The Salvation Army office in their county.
Supporting our communities
The Gulf Power Foundation gave $500,000 to United Way organizations across Northwest Florida to assist those most vulnerable during this time, which has helped support food, housing and other essential needs throughout the region. In addition, the Foundation recently made a $10,000 donation to Feeding the Gulf Coast and launched an employee donation campaign to provide food for our neighbors in need, while Entergy emergency relief fund offers a similar example of industry support. In total, Gulf Power and its fellow NextEra Energy companies and employees have so far committed more than $4 million in COVID-19 emergency assistance funds that will be distributed directly to those in need and to partner organizations working on the frontlines of the crisis to provide critical support to the most vulnerable members of the community.
Lower fuel costs are enabling Gulf Power to issue a one-time decrease of approximately 40% for the typical residential customer bill in May, even as FPL faces a hurricane surcharge controversy in the state - a significant savings amid the ongoing COVID-19 pandemic
Gulf Power will deliver savings to customers through a one-time bill decrease, rather than the standard practice of spreading out savings over the remainder of the year, even as FPL proposes multi-year rate hikes elsewhere
Atlanta Airport Power Outage disrupts Hartsfield-Jackson as an underground fire cripples switchgear redundancy, canceling flights during holiday travel; Georgia Power restores electricity overnight while utility crews probe causes and monitor system resilience.
Key Points
A major Hartsfield-Jackson blackout from an underground fire; power restored as switchgear redundancy is investigated.
✅ Underground fire near Plane Train tunnel damaged switchgear systems
✅ Over 1,100 flights canceled; holiday travel severely disrupted
✅ Georgia Power restored service; redundancy and root cause under review
Power has been restored at the world’s busiest airport after a massive outage Sunday afternoon left planes and passengers stranded for hours, forced airlines to cancel more than 1,100 flights and created a logistical nightmare during the already-busy holiday travel season.
An underground fire caused a complete power outage Sunday afternoon at Hartsfield-Jackson Atlanta International Airport, resulting in thousands of canceled flights at the world's busiest terminal and affecting travelers worldwide.
The massive outage didn’t just leave passengers stranded overnight Sunday, it also affected travelers with flights Monday morning schedules.
According to Paul Bowers, the president and CEO of Georgia Power, “From our standpoint, we apologize for the inconvenience,” he said. The utility restored power to the airport shortly before midnight.
Utility Crews are monitoring the fixes that restored power and investigating what caused the fire and why it was able to damage redundant systems. Bowers said the fire occurred in a tunnel that runs along the path of the underground Plane Train tunnel near Concourse E.
Sixteen highly trained utility personnel worked in the passageway to reconnect the network.“Our investigation is going through the process of what do we do to ensure we have the redundancy going back at the airport, because right now we are a single source feed,” Bowers said.
“We will have that complete by the end of the week, and then we will turn to what caused the failure of the switchgear.”
Though the cause isn’t yet known, he said foul play is not suspected.“There are two things that could happen,” he said.
“There are inner workings of the switchgear that could create the heat that caused the fire, or the splicing going into that switchgear -- that the cable had a failure on that going into the switch gear.”
When asked if age of the system could have been a failure, Bowers said his company conducts regular inspections.“We constantly inspect,” he said. “We inspect on an annual basis to ensure the reliability of the network, and that redundancy is protection for the airport.”Bowers said he is not familiar with any similar fire or outage at the airport.
“The issue for us is to ensure the reliability is here and that it doesn’t happen again and to ensure that our network is resilient enough to withstand any kind of fire,” he said. He added that Georgia Power will seek to determine what can be done in the future to avoid a similar event, such as those experienced during regional outages in other communities.
Alberta Electricity Market Reforms aim to boost grid reliability and efficiency through a day-ahead market, transmission policy changes, clearer pricing signals, AESO oversight, and smarter siting near existing infrastructure to lower consumer costs.
Key Points
Policies add a day-ahead market and transmission fees to modernize the grid and improve reliability.
✅ Day-ahead market for clearer pricing and scheduling
✅ Up-front, non-refundable transmission payments by generators
✅ AESO to draft new rules by end of 2025
The Alberta government is implementing significant electricity policy changes to its electricity market to enhance system reliability and efficiency. These reforms aim to modernize the grid, accommodate growing energy demands, and align with best practices observed in other jurisdictions.
Proposed Market Reforms
The government has outlined several key initiatives:
Day-Ahead Market Implementation: Introducing a day-ahead market is intended to provide clearer pricing signals and improve the scheduling of electricity generation. This approach allows market participants to plan and commit to energy production in advance, enhancing grid stability.
Transmission Policy Revisions: The government proposes reforms to transmission policies, including the introduction of up-front and non-refundable transmission payments from new power generators. These payments would vary based on the proximity of new generators to existing transmission lines with available capacity. As part of a broader market overhaul, this strategy encourages the development of power plants in areas where existing infrastructure can be utilized, potentially reducing costs for consumers and businesses.
Government's Objectives
Minister of Affordability and Utilities, Nathan Neudorf, emphasized that these changes are necessary to meet growing energy demands and modernize Alberta’s electricity system. The government's goal is to create a more reliable and efficient electrical system that benefits both consumers and the broader economy.
Industry Reactions
The proposed reforms have elicited mixed reactions from industry stakeholders amid profound sector change across Alberta:
Renewable Energy Sector Concerns: The Canadian Renewable Energy Association (CanREA) has expressed concerns about the potential for punitive market and transmission changes, and some retailers have similarly urged caution. They advocate for policies that support the integration of renewable energy sources and ensure fair treatment within the market.
Regulatory Oversight: The Alberta Electric System Operator (AESO) is tasked with preparing restructured energy market rules by the end of 2025. This timeline reflects the government's commitment to a thorough and consultative approach to market reform.
Implications for Consumers
The Alberta government's proposed market changes aim to enhance the reliability and efficiency of the electricity system by considering measures such as a Rate of Last Resort to provide additional stability. By encouraging the development of power plants in areas with existing infrastructure, the reforms seek to reduce costs for consumers and businesses. However, the success of these initiatives will depend on careful implementation and ongoing engagement with all stakeholders to balance the diverse interests involved.
Alberta's proposed electricity market reforms represent a significant step toward modernizing the province's energy infrastructure. By introducing a day-ahead market and revising transmission policies, the government aims to create a more reliable and efficient electrical system and promote market competition more effectively. While these changes have generated diverse reactions, they underscore the government's commitment to addressing the evolving energy needs of Alberta's residents and businesses.
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.
