Tennessee ranks 14th in the nation in carbon emissions, 16th in per capita energy consumption and first in per capita electricity consumption.
In other words, as the cost - both economically and environmentally - of energy consumption rises, there is work to be done in managing and reducing the state's energy appetite.
The Governor's Task Force on Energy Policy convened for its first meeting to begin that work.
A presentation by Jeff Wadsworth, Battelle executive and former director of Oak Ridge National Laboratory, launched the more than two-hour meeting at the Tennessee Department of Labor and Workforce Development's new "green" headquarters in Nashville.
Wadsworth's remarks - including the above-mentioned state energy statistics - were followed by presentations from William Bauer, program manager for the state's building energy management program, and William Rusie, assistant commissioner of Tennessee's Department of General Services.
The task force is made up of 17 representatives appointed by Gov. Phil Bredesen from state and local governments, businesses, utilities and research organizations.
Local representatives on the task force include Dana Christensen, associate laboratory director for energy and engineering at ORNL, and Knoxville architect Elizabeth Eason.
Bredesen moderated the meeting and set goals for the task force, which will meet for the next several months to outline short- and long-term energy goals for the state.
The group has been directed to develop a statewide energy policy, which Bredesen has said he hopes will give Tennessee leadership status in a growing area of interest across the nation.
As the meeting began, Bredesen set out three goals he hopes the task force will focus on in the months ahead.
"Energy is obviously an enormous issue," he said. "What I'm really hoping to do with this group in the next few monthsÂ… (is) find some attainable goals and meet them."
The first would be tackling the "low-hanging fruit" of greening the state's own operations.
The state owns 9 million square feet of buildings and owns a fleet of 5,000 vehicles that Bredesen said should be an easy target for energy savings and renewable- energy initiatives.
Second, he said, would be to develop comprehensive public- and private-sector legislation aimed at improving the state's energy statistics.
Such a package, while too late for introduction during the current General Assembly, could be ready to go next year.
Third, he said, "I want us to think about how we use some of the assets we have in Tennessee, ORNL for example, to help drive the development of clean energy technology as an economic tool.Â… This is an area where we could take a leadership position as a state."
Japan Offshore Wind Investment signals Japanese utilities entering UK offshore wind, as J-Power and Kansai Electric buy into Innogy's Triton Knoll, leveraging North Sea expertise, 9.5MW turbines, and 15-year fixed-rate contracts.
Key Points
Japanese utilities buying UK offshore wind stakes to import expertise, as J-Power and Kansai join Innogy's Triton Knoll.
✅ $900M deal: J-Power 25%, Kansai Electric ~16% in Innogy unit
✅ Triton Knoll: 860MW, up to 90 9.5MW turbines, 15-year fixed PPA
✅ Goal: Transfer North Sea expertise to develop Japan offshore wind
Two of Japan's biggest power companies will buy around 40% of a German-owned developer of offshore wind farms in the U.K., seeking to learn from Britain's lead in this sector, as highlighted by a UK offshore wind milestone this week, and bring the know-how back home.
Tokyo-based Electric Power Development, better known as J-Power, will join Osaka regional utility Kansai Electric Power in investing in a unit of Germany's Innogy.
The deal, estimated to be worth around $900 million, will give J-Power a 25% stake and Kansai Electric a roughly 16% share. It will mark the first investment in an offshore wind project by Japanese power companies, as other markets shift strategies, with Poland backing wind over nuclear signaling broader momentum.
Innogy plans to start up the 860-megawatt Triton Knoll offshore wind project -- one of the biggest of its kind in the world -- in the North Sea in 2021. The vast installation will have up to 90 9.5MW turbines and sell its output to local utilities under a 15-year fixed-rate contract.
J-Power, which supplies mainly fossil-fuel-based electricity to Japanese regional utilities, will set up a subsidiary backed by the government-run Development Bank of Japan to participate in the Innogy project. Engineers will study firsthand construction and maintenance methods.
While land-based wind turbines are proliferating worldwide, offshore wind farms have progressed mainly in Europe, though U.S. offshore wind competitiveness is improving in key markets. Installed capacity totaled more than 18,000MW at the end of 2017, which at maximum capacity can produce as much power as 18 nuclear reactors.
Japan has hardly any offshore wind farms in commercial operation, and has little in the way of engineering know-how in this field or infrastructure for linking such installations to the land power grid, with a recent Japan grid blackout analysis underscoring these challenges. But there are plans for a total of 4,000MW of offshore wind power capacity, including projects under feasibility studies.
J-Power set up a renewable energy division in June to look for opportunities to expand into wind and geothermal energy in Japan, and efforts like a Japan hydrogen energy system are emerging to support decarbonization. Kansai Electric also seeks know-how for increasing its reliance on renewable energy, even as it hurries to restart idled nuclear reactors.
They are not the only Japanese investors is in this field. In Asia, trading house Marubeni will invest in a Taiwanese venture with plans for a 600MW offshore wind farm.
BC Hydro Peak Electricity Demand reached a record 10,902 megawatts during a cold snap, driven by home heating. Peak hours surged; load shifting and energy conservation can ease strain on the grid and lower bills.
Key Points
Record winter peak of 10,902 MW, set during a cold snap, largely from home heating demand at peak hours.
✅ All-time high load: 10,902 MW between 5 and 6 p.m., Dec. 27.
✅ Cold snap increased home heating demand during peak hours.
✅ Shift laundry and dishwashers off-peak; use programmable thermostats.
BC Hydro says the province set a new record for peak electricity demand on Monday as temperatures hit extreme lows, and Quebec shattered consumption records during similar cold weather.
Between 5 and 6 p.m. on Dec. 27, demand for electricity hit an all-time high of 10,902 megawatts, which is higher than the previous record of 10,577 megawatts set in 2020, and follows a record-breaking year in 2021 for the utility.
“The record represents a single moment in the hour when demand for electricity was the highest yesterday,” says Simi Heer, BC Hydro spokesperson, in a statement. “Most of the increase is likely due to additional home heating required during this cold snap.”
In addition to the peak demand record on Monday, BC Hydro has observed an overall increase in electricity demand since Friday, and has noted that cryptocurrency mining electricity use is an emerging load in the province as well. Monday’s hourly peak demand was 18 per cent higher than Friday’s, while Calgary's electricity use soared during a frigid February, underscoring how cold snaps strain regional grids.
“BC Hydro has enough supply options in place to meet increasing electricity demand,” adds Heer, and pointed to customer supports like a winter payment plan for households managing higher bills. “However, if British Columbians want to help ease some of the demand on the system during peak times, we encourage shifting activities like doing laundry or running dishwashers to earlier in the day or later in the evening.”
BC Hydro is also offering energy conservation tips for people looking to lower their electricity use and their electricity bills, noting that Earth Hour once saw electricity use rise in the province:
Manage your home heating actively by turning the heat down when no one his home or when everyone is sleeping. Consider installing a programmable thermostat to automatically adjust temperatures at different times based on your family's activities, and remember that in warmer months wasteful air conditioning can add $200 to summer energy bills. BC Hydro recommends the following temperatures:
16 degrees Celsius when sleeping or away from home 21 degrees Celsius when relaxing, watching TV 18 degrees Celsius when doing housework or cleaning
US Electricity Demand 2018-2050 projects slower growth as energy consumption, power generation, air conditioning, and electric heating shift with efficiency standards, commercial floor space, industrial load, and household growth across the forecast horizon.
Key Points
A forecast of US power use across homes, commercial space, industrial load, and efficiency trends from 2018 to 2050.
✅ 2018 generation hit record; residential sales up 6%.
✅ Efficiency curbs demand; growth lags population and floor space.
✅ Commercial sales up 2%; industrial demand fell 3% in 2018.
Last year's Houston cold winter and hot summer drove power use to record levels, especially among households that rely on electricity for air conditioning during extreme weather conditions.
Electricity generation increased 4 per cent nationwide in 2018 and produced 4,178 million megawatt hours, driven in part by record natural gas generation across the U.S., surpassing the previous peak of 4,157 megawatt hours set in 2007, the Energy Department reported.
U.S. households bought 6 percent more electricity in 2018 than they did the previous year, despite longer-term declines in national consumption, reflecting the fact 87 percent of households cool their homes with air conditioning and 35 percent use electricity for heating.
Electricity sales to the commercial sector increased 2 percent in 2018 compared to the previous year while the industrial sector bought 3 percent less last year.
Going forward, the Energy Department forecasts that electricity consumption will grow at a slower pace than in recent decades, aligning with falling sales projections as technology improves and energy efficiency standards moderate consumption.
The economy and population growth are primary drivers of demand and the government predicts the number of households will grow at 0.7 percent per year from now until 2050 but electricity demand will grow only by 0.4 percent annually.
Likewise, commercial floor space is expected to increase 1 percent per year from now until 2050 but electricity sales will increase only by half that amount.
Globally, surging electricity demand is putting power systems under strain, providing context for these domestic trends.
Global Electricity Demand Surge underscores rising coal generation, lagging renewables deployment, and escalating emissions, as nations prioritize reliable power; nuclear energy and grid decarbonization emerge as pivotal solutions to the electricity transition.
Key Points
A rapid post-lockdown rise in power consumption, outpacing renewables growth and driving higher coal use and emissions.
✅ Coal generation rises faster than wind and solar additions
✅ Emissions increase as economies prioritize reliable baseload power
✅ Nuclear power touted for rapid grid decarbonization
By Robert Bryce
As the Covid lockdowns are easing, the global economy is recovering and that recovery is fueling blistering growth in electricity use. The latest data from Ember, the London-based “climate and energy think tank focused on accelerating the global electricity transition,” show that global power demand soared by about 5% in the first half of 2021. That’s faster growth than was happening back in 2018 when electricity use was increasing by about 4% per year.
The numbers from Ember also show that despite lots of talk about the urgent need to reduce greenhouse gas emissions, coal demand for power generation continues to grow and emissions from the electric sector continue to grow: up by 5% over the first half of 2019. In addition, they show that while about half of the growth in electricity demand was met by wind and solar, as low-emissions sources are set to cover almost all new demand over the next three years, overall growth in electricity use is still outstripping the growth in renewables.
The soaring use of electricity, and increasing emissions from power generation confirm the sage wisdom of Rasheed Wallace, the volatile former power forward with the Detroit Pistons and other NBA teams, and now an assistant coach at the University of Memphis, who coined the catchphrase: “Ball don’t lie.” If Wallace or one of his teammates was called for a foul during a basketball game that he thought was undeserved, and the opposing player missed the ensuing free throws, Wallace would often holler, “ball don’t lie,” as if the basketball itself was pronouncing judgment on the referee’s errant call.
I often think about Wallace’s catchphrase while looking at global energy and power trends and substitute my own phrase: numbers don’t lie.
Over the past few weeks Ember, BP, and the International Energy Agency have all published reports which come to the same two conclusions: that countries all around the world — and China's electricity sector in particular — are doing whatever they need to do to get the electricity they need to grow their economies. Second, they are using lots of coal to get that juice.
As I discuss in my recent book, A Question of Power: Electricity and the Wealth of Nations, Electricity is the world’s most important and fastest-growing form of energy. The Ember data proves that. At a growth rate of 5%, global electricity use will double in about 14 years, and as surging electricity demand is putting power systems under strain around the world, the electricity sector also accounts for the biggest single share of global carbon dioxide emissions: about 25 percent. Thus, if we are to have any hope of cutting global emissions, the electricity sector is pivotal. Further, the soaring use of electricity shows that low-income people and countries around the world are not content to stay in the dark. They want to live high-energy lives with access to all the electronic riches that we take for granted.
Ember’s data clearly shows that decarbonizing the global electric grid will require finding a substitute for coal. Indeed, coal use may be plummeting in the U.S. and western Europe, where U.S. electricity consumption has been declining, but over the past two years, several developing countries including Mongolia, China, Bangladesh, Vietnam, Kazakhstan, Pakistan, and India, all boosted their use of coal. This was particularly obvious in China, where, between the first half of 2019 and the first half of 2021, electricity demand jumped by about 14%. Of that increase, coal-fired generation provided roughly twice as much new electricity as wind and solar combined. In Pakistan, electricity demand jumped by about 7%, and coal provided more than three times as much new electricity as nuclear and about three times as much as hydro. (Wind and solar did not grow at all in Pakistan over that period.)
Hate coal all you like, but its century-long persistence in power generation proves its importance. That persistence proves that climate change concerns are not as important to most consumers and policymakers as reliable electricity. In 2010, Roger Pielke Jr. dubbed this the Iron Law of Climate Policy which says “When policies on emissions reductions collide with policies focused on economic growth, economic growth will win out every time.” Pielke elaborated on that point, saying the Iron Law is a “boundary condition on policy design that is every bit as limiting as is the second law of thermodynamics, and it holds everywhere around the world, in rich and poor countries alike. It says that even if people are willing to bear some costs to reduce emissions (and experience shows that they are), they are willing to go only so far.”
Over the past five years, I’ve written a book about electricity, co-produced a feature-length documentary film about it (Juice: How Electricity Explains the World), and launched a podcast that focuses largely on energy and power. I’m convinced that Pielke’s claim is exactly right and should be extended to electricity and dubbed the Iron Law of Electricity which says, “when forced to choose between dirty electricity and no electricity, people will choose dirty electricity every time.” I saw this at work in electricity-poor places all over the world, including India, Lebanon, and Puerto Rico.
Pielke, a professor at the University of Colorado as well as a highly regarded author on the politics of climate change and sports governance, has since elaborated on the Iron Law. During an interview in Juice, he explained it thusly: “The Iron Law says we’re not going to reduce emissions by willingly getting poor. Rich people aren't going to want to get poorer, poor people aren't going to want to get poorer.” He continued, “If there is one thing that we can count on it is that policymakers will be rewarded by populations if they make people wealthier. We're doing everything we can to try to get richer as nations, as communities, as individuals. If we want to reduce emissions, we really have only one place to go and that's technology.”
Pielke’s point reminds me of another of my favorite energy analysts, Robert Rapier, who made a salient point in his Forbes column last week. He wrote, “Despite the blistering growth rate of renewables, it’s important to keep in mind that overall global energy consumption is growing. Even though global renewable energy consumption has increased by about 21 exajoules in the past decade, overall energy consumption has increased by 51 exajoules. Increased fossil fuel consumption made up most of this growth, with every category of fossil fuels showing increased consumption over the decade.”
The punchline here – despite my tangential reference to Rasheed Wallace — is obvious: The claims that massive reductions in global carbon dioxide emissions must happen soon are being mocked by the numbers. Countries around the world are acting in their interest, particularly when it comes to their electricity needs and that is resulting in big increases in emissions. As Ember concludes in their report, wind and solar are growing, and some analyses suggest renewables could eclipse coal by 2025, but the “electricity transition” is “not happening fast enough.”
Ember explains that in the first half of 2021, wind and solar output exceeded the output of the world’s nuclear reactors for the first time. It also noted that over the past two years, “Nuclear generation fell by 2% compared to pre-pandemic levels, as closures at older plants across the OECD, especially amid debates over European nuclear trends, exceeded the new capacity in China.” While that may cheer anti-nuclear activists at groups like Greenpeace and Friends of the Earth, the truth is obvious: the only way – repeat, the only way – the electric sector will achieve significant reductions in carbon dioxide emissions is if we can replace lots of coal-fired generation with nuclear reactors and do so in relatively short order, meaning the next decade or so. Renewables are politically popular and they are growing, but they cannot, will not, be able to match the soaring demand for the electricity that is needed to sustain modern economies and bring developing countries out of the darkness and into modernity.
Countries like China, Vietnam, India, and others need an alternative to coal for power generation. They need new nuclear reactors that are smaller, safer, and cheaper than the existing designs. And they need it soon. I will be writing about those reactors in future columns.
US Climate Alliance 100% Renewables 2035 accelerates clean energy, electrification, and decarbonization, replacing coal and gas with wind, solar, and storage to cut air pollution, lower energy bills, create jobs, and advance environmental justice.
Key Points
A state-level target for alliance members to meet all electricity demand with renewable energy by 2035.
✅ 100% RES can meet rising demand from electrification
✅ Major health gains from reduced SO2, NOx, and particulates
✅ Jobs grow, energy burdens fall, climate resilience improves
The Union of Concerned Scientists joined with COPAL (Minnesota), GreenRoots (Massachusetts), and the Michigan Environmental Justice Coalition, to better understand the feasibility and implications of leadership states meeting 100 percent of their electricity needs with renewable energy by 2035, a target reflected in federal clean electricity goals under discussion today.
We focused on 24 member states of the United States Climate Alliance, a bipartisan coalition of governors committed to the goals of the 2015 Paris Climate Agreement. We analyzed two main scenarios: business as usual versus 100 percent renewable electricity standards, in line with many state clean energy targets now in place.
Our analysis shows that:
Climate Alliance states can meet 100 percent of their electricity consumption with renewable energy by 2035, as independent assessments of zero-emissions feasibility suggest. This holds true even with strong increases in demand due to the electrification of transportation and heating.
A transition to renewables yields strong benefits in terms of health, climate, economies, and energy affordability.
To ensure an equitable transition, states should broaden access to clean energy technologies and decision making to include environmental justice and fossil fuel-dependent communitieswhile directly phasing out coal and gas plants.
Demands for climate action surround us. Every day brings news of devastating "this is not normal" extreme weather: record-breaking heat waves, precipitation, flooding, wildfires. To build resilience and mitigate the worst impacts of the climate crisis requires immediate action to reduce heat-trapping emissions and transition to renewable energy, including practical decarbonization strategies adopted by states.
On the Road to 100 Percent Renewables explores actions at one critical level: how leadership states can address climate change by reducing heat-trapping emissions in key sectors of the economy as well as by considering the impacts of our energy choices. A collaboration of the Union of Concerned Scientists and local environmental justice groups COPAL (Minnesota), GreenRoots (Massachusetts), and the Michigan Environmental Justice Coalition, with contributions from the national Initiative for Energy Justice, assessed the potential to accelerate the use of renewable energy dramatically through state-level renewable electricity standards (RESs), major drivers of clean energy in recent decades. In addition, the partners worked with Greenlink Analytics, an energy research organization, to assess how RESs most directly affect people's lives, such as changes in public health, jobs, and energy bills for households.
Focusing on 24 members of the United States Climate Alliance (USCA), the study assesses the implications of meeting 100 percent of electricity consumption in these states, including examples like Rhode Island's 100% by 2030 plan that inform policy design, with renewable energy in the near term. The alliance is a bipartisan coalition of governors committed to reducing heat-trapping emissions consistent with the goals of the 2015 Paris climate agreement.[1]
On the Road to 100 Percent Renewables looks at three types of results from a transition to 100 percent RES policies: improvements in public health from decreasing the use of coal and gas2 power plants; net job creation from switching to more labor-oriented clean energy; and reduced household energy bills from using cleaner sources of energy. The study assumes a strong push to electrify transportation and heating to address harmful emissions from the current use of fossil fuels in these sectors. Our core policy scenario does not focus on electricity generation itself, nor does it mandate retiring coal, gas, and nuclear power plants or assess new policies to drive renewable energy in non-USCA states.
Our analysis shows that:
USCA states can meet 100 percent of their electricity consumption with renewable energy by 2035 even with strong increases in demand due to electrifying transportation and heating.
A transition to renewables yields strong benefits in terms of health, climate, economies, and energy affordability.
Renewable electricity standards must be paired with policies that address not only electricity consumption but also electricity generation, including modern grid infrastructure upgrades that enable higher renewable shares, both to transition away from fossil fuels more quickly and to ensure an equitable transition in which all communities experience the benefits of a clean energy economy.
Currently, the states in this analysis meet their electricity needs with differing mixes of electricity sourcesfossil fuels, nuclear, and renewables. Yet across the states, the study shows significant declines in fossil fuel use from transitioning to clean electricity; the use of solar and wind powerthe dominant renewablesgrows substantially:
In the study's "No New Policy" scenario"business as usual"coal and gas generation stay largely at current levels over the next two decades. Electricity generation from wind and solar grows due to both current policies and lowest costs.
In a "100% RES" scenario, each USCA state puts in place a 100 percent renewable electricity standard. Gas generation falls, although some continues for export to non-USCA states. Coal generation essentially disappears by 2040. Wind and solar generation combined grow to seven times current levels, and three times as much as in the No New Policy scenario.
A focus on meeting in-state electricity consumption in the 100% RES scenario yields important outcomes. Reductions in electricity from coal and gas plants in the USCA states reduce power plant pollution, including emissions of sulfur dioxide and nitrogen oxides. By 2040, this leads to 6,000 to 13,000 fewer premature deaths than in the No New Policy scenario, as well as 140,000 fewer cases of asthma exacerbation and 700,000 fewer lost workdays. The value of the additional public health benefits in the USCA states totals almost $280 billion over the two decades. In a more detailed analysis of three USCA statesMassachusetts, Michigan, and Minnesotathe 100% RES scenario leads to almost 200,000 more added jobs in building and installing new electric generation capacity than the No New Policy scenario.
The 100% RES scenario also reduces average energy burdens, the portion of household income spent on energy. Even considering household costs solely for electricity and gas, energy burdens in the 100% RES scenario are at or below those in the No New Policy scenario in each USCA state in most or all years. The average energy burden across those states declines from 3.7 percent of income in 2020 to 3.0 percent in 2040 in the 100% RES scenario, compared with 3.3 percent in 2040 in the No New Policy scenario.
Decreasing the use of fossil fuels through increasing the use of renewables and accelerating electrification reduces emissions of carbon dioxide (CO2), with implications for climate, public health, and economies. Annual CO2 emissions from power plants in USCA states decrease 58 percent from 2020 to 2040 in the 100% RES scenario compared with 12 percent in the No New Policy scenario.
The study also reveals gaps to be filled beyond eliminating fossil fuel pollution from communities, such as the persistence of gas generation to sell power to neighboring states, reflecting barriers to a fully renewable grid that policy must address. Further, it stresses the importance of policies targeting just and equitable outcomes in the move to renewable energy.
Moving away from fossil fuels in communities most affected by harmful air pollution should be a top priority in comprehensive energy policies. Many communities continue to bear far too large a share of the negative impacts from decades of siting the infrastructure for the nation's fossil fuel power sector in or near marginalized neighborhoods. This pattern will likely persist if the issue is not acknowledged and addressed. State policies should mandate a priority on reducing emissions in communities overburdened by pollution and avoiding investments inconsistent with the need to remove heat-trapping emissions and air pollution at an accelerated rate. And communities must be centrally involved in decisionmaking around any policies and rules that affect them directly, including proposals to change electricity generation, both to retire fossil fuel plants and to build the renewable energy infrastructure.
Key recommendations in On the Road to 100 Percent Renewables address moving away from fossil fuels, increasing investment in renewable energy, and reducing CO2 emissions. They aim to ensure that communities most affected by a history of environmental racism and pollution share in the benefits of the transition: cleaner air, equitable access to good-paying jobs and entrepreneurship alternatives, affordable energy, and the resilience that renewable energy, electrification, energy efficiency, and energy storage can provide. While many communities can benefit from the transition, strong justice and equity policies will avoid perpetuating inequities in the electricity system. State support to historically underserved communities for investing in solar, energy efficiency, energy storage, and electrification will encourage local investment, community wealth-building, and the resilience benefits the transition to renewable energy can provide.
A national clean electricity standard and strong pollution standards should complement state action to drive swift decarbonization and pollution reduction across the United States. Even so, states are well positioned to simultaneously address climate change and decades of inequities in the power system. While it does not substitute for much-needed national and international leadership, strong state action is crucial to achieving an equitable clean energy future.
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.
