US Army deploys its first floating solar array

Nova Scotia’s West Wind Clean Energy Project aims to harness offshore wind power to deliver renewable electricity, expand transmission infrastructure, and position Canada as a global leader in sustainable energy generation.

What is West Wind Clean Energy?

The West Wind Clean Energy Project is Nova Scotia’s $60-billion offshore wind initiative to generate up to 66 GW of clean electricity for Canada’s growing energy needs.

✅ Harnesses offshore wind resources for renewable power generation

✅ Expands grid and transmission infrastructure for clean energy exports

✅ Supports Canada’s transition to a sustainable, low-carbon economy

Nova Scotia has launched one of the most ambitious clean energy projects in Canadian history — a $60-billion plan to build 66 gigawatts (GW) of offshore wind capacity, as countries like the UK expand offshore wind, capable of meeting up to 27 per cent of the nation’s total electricity demand.

Premier Tim Houston unveiled the project, called West Wind, in June, positioning it as a cornerstone of Canada’s broader energy transition and aligning it with Prime Minister Mark Carney’s goal of making the country both a clean energy and conventional energy superpower. Three months later, Carney announced a slate of “nation-building” infrastructure projects the federal government would fast-track. While West Wind was not on the initial list, it was included in a second tier of high-potential proposals still under development.

The plan’s scale is unprecedented for Canada’s offshore energy industry, as organizations like Marine Renewables Canada pivot toward offshore wind to accelerate growth. However, enormous logistical, financial, and market challenges remain. Turbines will not be in the water for years, and the global offshore wind industry itself is facing one of its most difficult periods in over a decade.

“Right now is probably the worst time in 15 years to launch a project like this,” said an executive at a Canadian energy company who requested anonymity. “It’s not Nova Scotia’s fault. It’s just really bad timing.” He pointed to failed offshore wind auctions in Europe, rising costs, and policy reversals in the United States as troubling signals for investors, even as New York’s largest offshore wind project moved ahead this year. “You can’t build the wind and hope the lines come later. You have to build both — together.”

Indeed, transmission infrastructure is emerging as the project’s biggest obstacle. Nova Scotia’s local electricity demand is limited, meaning most of the power would need to be sold to markets in Ontario, Quebec, and New England. Of the $60 billion budgeted for West Wind, $40 billion is allocated to generation, and $20 billion to new transmission — massive sums that require close federal-provincial coordination and long-term investment planning.

Despite the economic headwinds, advocates argue that West Wind could transform Atlantic Canada’s energy landscape and strengthen national energy security, building on recent tidal power investments in Nova Scotia. Peter Nicholson, chair of the Canadian Climate Institute and author of Catching the Wind: How Atlantic Canada Can Become an Energy Superpower, believes the project could redefine Nova Scotia’s role in Canada’s energy transition.

“It’s very well understood where the world is headed,” Nicholson said, noting that wind power is becoming increasingly competitive worldwide. “We’re moving toward an electrical future that’s cleanly generated for economic, environmental, and security reasons. But for that to happen, the economics have to work.” He added that the official “nation-building” designation could give Nova Scotia “a seat at the table” with major utilities in other provinces.

The governments of Canada and Nova Scotia recently issued a notice of strategic direction to the Canada–Nova Scotia Offshore Energy Regulator, aligning with Ottawa’s plan to regulate offshore wind as it begins a prequalification process and designs a call for bids later this year. The initial round will cover just 3 GW of capacity — smaller than the originally envisioned 5 GW — but officials describe it as a first step in a multi-decade plan.

While timing and economics remain uncertain, supporters insist the long-term potential of offshore wind in Nova Scotia is too significant to ignore. As global demand for clean electricity grows and offshore wind moves toward a trillion-dollar global market, they argue, West Wind could help secure Canada’s place as a renewable energy leader — if government and industry can find a way to make the numbers work.

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EV Charging Coal and Oil Claim: Fact-check of kWh, CO2 emissions, and electricity grid mix shows 70 lb coal or ~8 gallons oil per 66 kWh, with renewables and natural gas reducing lifecycle emissions.

Key Points

A viral claim on EV charging overstates oil use; accurate figures depend on grid mix: ~70 lb coal or ~8 gallons oil.

✅ About 70 lb coal or ~8 gal oil per 66 kWh, incl. conversion losses

✅ EVs average ~100 g CO2 per mile vs ~280 g for 30 mpg cars

✅ Grid mix includes renewables, nuclear, natural gas; oil use is low

The claim: Average electric car requires equivalent of 85 pounds of coal or six barrels of oil for a single charge

The Biden administration has pledged to work towards decarbonizing the U.S. electricity grid by 2035. And the recently passed $1.2 trillion infrastructure bill provides funding for more electric vehicle (EV) charging infrastructure, including EV charging networks across the country under current plans.

However, a claim that electric cars require an inordinate amount of oil or coal energy to charge has appeared on social media, even as U.S. plug-ins traveled 19 billion miles on electricity in 2021.

“An average electric car takes 66 KWH To charge. It takes 85 pounds of coal or six barrels of oil to make 66 KWH,” read a Dec 1 Facebook post that was shared nearly 500 times in a week. “Makes absolutely no sense.” 

The post included a stock image of an electric car charging, though actual charging costs depend on local rates and vehicle efficiency.

This claim is in the ballpark for the coal comparison, but the math on the oil usage is wildly inaccurate.

It would take roughly 70 pounds of coal to produce the energy required to charge a 66 kWh electric car battery, said Ian Miller, a research associate at the MIT Energy Initiative. That's about 15 pounds less than is claimed in the post.

The oil number is much farther off.

While the post claims that it takes six barrels of oil to charge a 66 kWh battery, Miller said the amount is closer to 8 gallons  — the equivalent of 20% of one barrel of oil.

He said both of his estimates account for energy lost when fossil fuels are converted into electricity. 

"I think the most important question is, 'How do EVs and gas cars compare on emissions per distance?'," said Miller. "In the US, using average electricity, EVs produce roughly 100 grams of CO2 per mile."

He said this is more than 60% less than a typical gasoline-powered car that gets 30 mpg, aligning with analyses that EVs are greener in all 50 states today according to recent studies. Such a vehicle produces roughly 280 grams of CO2 per mile.

Lifecycle analyses also show that the CO2 from making an EV battery is not equivalent to driving a gasoline car for years, which often counters common misconceptions.

"If you switch to an electric vehicle, even if you're using fossil fuels (to charge), it's just simply not true that you'll be using more fossil fuel," said Jessika Trancik, a professor at the Massachusetts Institute of Technology who studies the environmental impact of energy systems.  

However, she emphasized electric cars in the U.S. are not typically charged using only energy from coal or oil, and that electricity grids can handle EVs with proper management.

The U.S. electricity grid relies on a diversity of energy sources, of which oil and coal together make up about 20 percent, according to a DOE spokesperson. This amount is likely to continue to drop as renewable energy proliferates in the U.S., even as some warn that state power grids will be challenged by rapid EV adoption. 

"Switching to an electric vehicle means that you can use other sources, including less carbon-intensive natural gas, and even less carbon-intensive electricity sources like nuclear, solar and wind energy, which also carry with them health benefits in the form of reduced air pollutant emissions," said Trancik. 

Our rating: Partly false
Based on our research, we rate PARTLY FALSE the claim that the average electric car requires the equivalent of 85 pounds of coal or six barrels of oil for a single charge. The claim is in the ballpark on coal consumption, as an MIT researcher estimates that around 70 pounds. But the oil usage is only about 8 gallons, which is 20% of one barrel. And the actual sources of energy for an electric car vary depending on the energy mix in the local electric grid. 

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Biden Impact on Canadian Energy Exports highlights shifts in trade policy, tariffs, carbon pricing, and Keystone XL, with implications for aluminum, softwood lumber, electricity trade, fracking limits, and small modular nuclear reactors.

Key Points

How Biden-era trade, climate rules, and tariffs may reshape Canadian energy and exports.

✅ Reduced tariff volatility and friendlier trade policy toward allies

✅ Climate alignment: carbon pricing, clean power, cross-border electricity

✅ Potential gains for oil, gas, aluminum, and softwood lumber exporters

There is little doubt among industry associations, the Conference Board of Canada and C.D. Howe Institute that a Joe Biden White House will be better for Canadian resource and energy exporters – even Alberta’s beleaguered oil industry, despite Biden’s promise to kill the Keystone XL pipeline.

The consensus among industry observers in the lead-up to the November 3 U.S. presidential election was that a re-elected Donald Trump would become even more pugnacious on trade and protectionism, putting electricity exports at risk for Canadian utilities, which would be bad for Canadian exporters. The Justin Trudeau government would likely come under increased pressure to lower Canadian business taxes to compete with Trump’s low-tax climate.

“A Joe Biden victory would likely lead to higher taxes for both corporations and wealthy Americans to help pay down the gigantic fiscal deficit that is currently running at plus-US$5 trillion,” the conference board concluded in a recent analysis.

On trade and tariffs, the conference board said: “Many but not all of these ongoing trade disputes would wither away under a Joe Biden administration. He would likely run a broad trade policy favouring strategic allies like Canada.

While Canadian industries like forestry and aluminum smelting benefited from strong demand and prices in the U.S. under Trump, the forced renegotiation of the North American Free Trade Agreement failed end tariffs and duties on things like softwood lumber and aluminum ingots, even as Canadians backed tariffs on energy and minerals during the dispute.

The uncertainty over trade issues, and Trump’s tax cuts, which made Canada’s tax regime less competitive, have contributed to a period of low business investment in Canada during Trump's presidency.

“For Canada, we’ve seen a period, since this administration has been in power, where investment has eroded steadily,” conference board chief economist Pedro Antunes said. “We are not doing well at all, in terms of private capital investment in Canada.”

Alberta’s oil industry has been hit particularly hard, with a slew of divestments by big energy giants, and cancellations of major projects, like the $20 billion Frontier oilsands project, scrubbed by Teck Resources.

While domestic policies and global market forces are partly to blame for falling investments in Canada’s oil and gas sector, up until the pandemic hit, investment in oil and gas increased significantly in the U.S., while declining in Canada, during Trump’s first term.

Biden is also expected to level the playing field with respect to climate change policies. Canadian industries pay carbon taxes and face regulations that their counterparts in the U.S. don’t. That has disadvantaged energy-intensive, trade-exposed industries like mines and pulp mills in Canada.

“With Biden in office, Canada will once again have a partner at the federal level in the states in the transition to a decarbonized economy,” said Josha MacNab, national policy director for the Pembina Institute.

Biden’s policies might also favour importing aluminum, cross-laminated timber, fuel cells and other lower-carbon products and commodities from Canada.

At least one observer believes that Canada’s oil and gas sector might benefit more from a Biden White House, despite Biden’s pledge to kill the Keystone XL pipeline.

“I think Joe Biden could be very good for Alberta,” Christopher Sands, director of the Wilson International Center’s Canada Institute, said in a recent discussion hosted by the C.D. Howe Institute.

Sands added that the presidential permit Biden has promised to tear up on the Keystone XL pipeline project is a construction permit, not an operating permit.

“The segment of that pipeline that crosses the U.S.-Canada border, which is the only place that the presidential permit applies, has been built,” Sands said. “So I think that’s somewhat of an empty threat.”

He added that, if Biden bans fracking on federal lands, as he has promised, and implements other restrictions that make it more costly for American oil and gas producers, it might increase the demand for Canadian oil and gas in the U.S. The demand would be highest in the U.S. Midwest, which depends largely on Marcellus Shale production, notably in Pennsylvania, and Western Canada for its oil and gas.

One of the Canadian industries directly affected by the Trump administration was aluminum smelting, which is relevant for B.C. because Rio Tinto plc’s Kitimat smelter exports aluminum to the U.S.

Jean Simard, president of the Aluminum Association of Canada, said one of Trump’s legacies was the reactivation of a little-used mechanism – Section 232 of the Trade Expansion Act – to hit Canada and other countries, notably China, with import tariffs.

The 10 per cent tariffs on aluminum cost Canadian aluminum producers US$15 million in the month of August alone, Simard said.

The Trump administration eventually exempted Canadian aluminum exports from the tariffs, then reintroduced them, and then, one week before the election, exempted them again.

These on-again, off-again tariff threats create tremendous uncertainty, not just for Canadian producers, but also for U.S. buyers. That kind of uncertainty is likely to ease under a Biden presidency.

Simard said Biden’s track record suggests he is well-disposed towards Canada and less confrontational with allies and trade partners in general, and some in Washington have called for a stronger U.S.-Canada energy partnership as well.

Meanwhile, softwood lumber tariffs have been imposed by Democrats and Republicans alike. But there are compelling reasons for ending the Canada-U.S. softwood lumber war.

Home renovation and repair in the United States has done surprisingly well during the pandemic.

As a result of sawmill curtailments in the U.S. due to pandemic restrictions and high demand for lumber in the U.S. housing sector, North American lumbers prices broke records this summer, soaring as high as US$900 per thousand board feet.

“It shows that there’s very strong demand for our product,” said Susan Yurkovich, president of the Council of Forest Industries.

Ultimately, the duties Canadian lumber exporters pay are passed on to U.S. consumers.

Sands said Biden’s climate action pledges, including a clean electricity standard, could increase opportunities for trading electricity between Canada in the U.S., as the U.S. increasingly looks to Canada for green power, and could also be good for Canadian nuclear power technology.

Strong climate change policies necessarily result in an increased demand for low-carbon electricity, and advancing clean grids, which Canada has in abundance, thanks to both hydro and nuclear power.

“[Biden] does share the desire to act on climate change, but unlike some of his fellow party members who are more signed on to a Green New Deal, he’s open to pragmatic solutions that might get the job done quickly and efficiently,” Sands said.

“This is a huge opportunity for small, modular nuclear reactors, and Atomic Energy Canada has some great designs. There’s a real opportunity for a nuclear revival.” 

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UK Renewable Grid Connection Delays threaten the 2035 zero-carbon electricity target as National Grid queues stall wind and solar projects, investors, and infrastructure, slowing clean energy deployment, curtailing capacity build-out, and risking net-zero progress.

Key Points

Prolonged National Grid queues delaying wind and solar connections, jeopardizing the UK's 2035 clean power target.

✅ Up to 15-year waits for grid connections

✅ Over £200bn projects stuck in the queue

✅ Threatens zero-carbon electricity by 2035

The UK currently has a 2035 target for 100% of its electricity to be produced without carbon emissions, while Ireland's green electricity progress offers a nearby benchmark within the next four years.

But meeting the target will require a big increase in the number of renewable projects across the country. It is estimated as much as five times more solar and four times as much wind is needed, with growth in UK offshore wind expected to play a key role here.

The government and private investors have spent £198bn on renewable power infrastructure since 2010, alongside European wind investments recorded last year. But now energy companies are warning that significant delays to connect their green energy projects to the system will threaten their ability to bring more green power online.

A new wind farm or solar site can only start supplying energy to people's homes once it has been plugged into the grid.

Energy companies like Octopus Energy, one of Europe's largest investors in renewable energy, say they have been told by National Grid that they need to wait up to 15 years for some connections, even as a new 10 GW contract aims to speed UK grid additions - far beyond the government's 2035 target.

'Longest grid queues in Europe'
There are currently more than £200bn worth of projects sitting in the connections queue, the BBC has calculated.

Around 40% of them face a connection wait of at least a year, according to National Grid's own figures. That represents delayed investments worth tens of billions of pounds, reflecting stalled grid spending that slows renewable rollouts.

"We currently have one of the longest grid queues in Europe," according to Zoisa North-Bond, chief executive of Octopus Energy Generation.

The problem is so many new renewable projects are applying for connections, the grid cannot keep up with required network expansion such as new pylons in Scotland being discussed nationwide.

The system was built when just a few fossil fuel power plants were requesting a connection each year, but now there are 1,100 projects in the queue, a challenge mirrored by U.S. grid hurdles in moving toward 100% renewables today.

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Canada Electricity Decarbonization Costs indicate challenging greenhouse gas reductions across a fragmented grid, with wind, solar, nuclear, and natural gas tradeoffs, significant GDP impacts, and Net Zero targets constrained by intermittency and limited interties.

Key Points

Costs to cut power CO2 via wind, solar, gas, and nuclear, considering grid limits, intermittency, and GDP impacts.

✅ Alberta model: eliminate coal; add wind, solar, gas; 26-40% CO2 cuts

✅ Nuclear option enables >75% cuts at higher but feasible system costs

✅ National costs 1-2% GDP; reserves, transmission, land, and waste not included

Along with many western developed countries, Canada has pledged to reduce its greenhouse gas emissions by 40–45 percent by 2030 from 2005 emissions levels, and to achieve net-zero emissions by 2050.

This is a huge challenge that, when considered on a global scale, will do little to stop climate change because emissions by developing countries are rising faster than emissions are being reduced in developed countries. Even so, the potential for achieving emissions reduction targets is extremely challenging as there are questions as to how and whether targets can be met and at what cost. Because electricity can be produced from any source of energy, including wind, solar, geothermal, tidal, and any combustible material, climate change policies have focused especially on nations’ electricity grids, and in Canada cleaning up electricity is viewed as critical to meeting climate pledges.

Canada’s electricity grid consists of ten separate provincial grids that are weakly connected by transmission interties to adjacent grids and, in some cases, to electricity systems in the United States. At times, these interties are helpful in addressing small imbalances between electricity supply and demand so as to prevent brownouts or even blackouts, and are a source of export revenue for provinces that have abundant hydroelectricity, such as British Columbia, Manitoba, and Quebec.

Due to generally low intertie capacities between provinces, electricity trade is generally a very small proportion of total generation, though electricity has been a national climate success in recent years. Essentially, provincial grids are stand alone, generating electricity to meet domestic demand (known as load) from the lowest cost local resources.

Because climate change policies have focused on electricity (viz., wind and solar energy, electric vehicles), and Canada will need more electricity to hit net-zero according to the IEA, this study employs information from the Alberta electricity system to provide an estimate of the possible costs of reducing national CO2 emissions related to power generation. The Alberta system serves as an excellent case study for examining the potential for eliminating fossil-fuel generation because of its large coal fleet, favourable solar irradiance, exceptional wind regimes, and potential for utilizing BC’s reservoirs for storage.

Using a model of the Alberta electricity system, we find that it is infeasible to rely solely on renewable sources of energy for 100 percent of power generation—the costs are prohibitive. Under perfect conditions, however, CO2 emissions from the Alberta grid can be reduced by 26 to 40 percent by eliminating coal and replacing it with renewable energy such as wind and solar, and gas, but by more than 75 percent if nuclear power is permitted. The associated costs are estimated to be some $1.4 billion per year to reduce emissions by at most 40 percent, or $1.9 billion annually to reduce emissions by 75 percent or more using nuclear power (an option not considered feasible at this time).

Based on cost estimates from Alberta, and Ontario’s experience with subsidies to renewable energy, and warnings that the switch from fossil fuels to electricity could cost about $1.4 trillion, the costs of relying on changes to electricity generation (essentially eliminating coal and replacing it with renewable energy sources and gas) to reduce national CO2 emissions by about 7.4 percent range from some $16.8 to $33.7 billion annually. This constitutes some 1–2 percent of Canada’s GDP.

The national estimates provided here are conservative, however. They are based on removing coal-fired power from power grids throughout Canada. We could not account for scenarios where the scale of intermittency turned out worse than indicated in our dataset—available wind and solar energy might be lower than indicated by the available data. To take this into account, a reserve market is required, but the costs of operating such a capacity market were not included in the estimates provided in this study. Also ignored are the costs associated with the value of land in other alternative uses, the need for added transmission lines, environmental and human health costs, and the life-cycle costs of using intermittent renewable sources of energy, including costs related to the disposal of hazardous wastes from solar panels and wind turbines.

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Electric Car Motors convert electricity to torque via rotor-stator magnetic fields, using AC/DC inverters, permanent magnets or induction designs; they power EV powertrains efficiently and enable regenerative braking for energy recovery and control.

Key Points

Electric car motors turn electrical energy into wheel torque using rotor-stator fields, inverters, and AC or DC control.

✅ AC induction, PMSM, BLDC, and reluctance architectures explained

✅ Inverters manage AC/DC, voltage, and motor speed via frequency

✅ Regenerative braking recovers energy and reduces wear

When was the last time you stopped to think about how electric cars actually work, especially if you're wondering whether to buy an electric car today? We superfans of the car biz have mostly developed a reasonable understanding of how combustion powertrains work. Most of us can visualize fuel and air entering a combustion chamber, exploding, pushing a piston down, and rotating a crankshaft that ultimately turns the wheels. We generally understand the differences between inline, flat, vee-shaped, and maybe even Wankel rotary combustion engines.

Mechanical engineering concepts such as these are comparatively easy to comprehend. But it's probably a fair bet to wager that only a minority of folks reading this can explain on a bar napkin exactly how invisible electrons turn a car's wheels or how a permanent-magnet motor differs from an AC induction one. Electrical engineering can seem like black magic and witchcraft to car nuts, so it's time to demystify this bold new world of electromobility, with the age of electric cars arriving ahead of schedule.

How Electric Cars Work: Motors
It has to do with magnetism and the natural interplay between electric fields and magnetic fields. When an electrical circuit closes allowing electrons to move along a wire, those moving electrons generate an electromagnetic field complete with a north and a south pole. When this happens in the presence of another magnetic field—either from a different batch of speeding electrons or from Wile E. Coyote's giant ACME horseshoe magnet, those opposite poles attract, and like poles repel each other.

Electric motors work by mounting one set of magnets or electromagnets to a shaft and another set to a housing surrounding that shaft. By periodically reversing the polarity (swapping the north and south poles) of one set of electromagnets, the motor leverages these attracting and repelling forces to rotate the shaft, thereby converting electricity into torque and ultimately turning the wheels, in a sector where the electric motor market is growing rapidly worldwide. Conversely—as in the case of regenerative braking—these magnetic/electromagnetic forces can transform motion back into electricity.

How Electric Cars Work: AC Or DC?
The electricity supplied to your home arrives as alternating current (AC), and bidirectional charging means EVs can power homes for days as needed, so-called because the north/south or plus/minus polarity of the power changes (alternates) 60 times per second. (That is, in the United States and other countries operating at 110 volts; countries with a 220-volt standard typically use 50-Hz AC.) Direct current (DC) is what goes into and comes out of the + and - poles of every battery. As noted above, motors require alternating current to spin. Without it, the electromagnetic force would simply lock their north and south poles together. It's the cycle of continually switching north and south that keeps a motor spinning.

Today's electric cars are designed to manage both AC and DC energy on board. The battery stores and dispenses DC current, but again, the motor needs AC. When recharging the battery, and with increasing grid coordination enabling flexibility, the energy comes into the onboard charger as AC current during Level 1 and Level 2 charging and as DC high-voltage current on Level 3 "fast chargers." Sophisticated power electronics (which we will not attempt to explain here) handle the multiple onboard AC/DC conversions while stepping the voltage up and down from 100 to 800 volts of charging power to battery/motor system voltages of 350-800 volts to the many vehicle lighting, infotainment, and chassis functions that require 12-48-volt DC electricity.

How Electric Cars Work: What Types Of Motors?
DC Motor (Brushed): Yes, we just said AC makes the motor go around, and these old-style motors that powered early EVs of the 1900s are no different. DC current from the battery is delivered to the rotor windings via spring-loaded "brushes" of carbon or lead that energize spinning contacts connected to wire windings. Every few degrees of rotation, the brushes energize a new set of contacts; this continually reverses the polarity of the electromagnet on the rotor as the motor shaft turns. (This ring of contacts is known as the commutator).

The housing surrounding the rotor's electromagnetic windings typically features permanent magnets. (A "series DC" or so-called "universal motor" may use an electromagnetic stator.) Advantages are low initial cost, high reliability, and ease of motor control. Varying the voltage regulates the motor's speed, while changing the current controls its torque. Disadvantages include a lower lifespan and the cost of maintaining the brushes and contacts. This motor is seldom used in transportation today, save for some Indian railway locomotives.

Brushless DC Motor (BLDC): The brushes and their maintenance are eliminated by moving the permanent magnets to the rotor, placing the electromagnets on the stator (housing), and using an external motor controller to alternately switch the various field windings from plus to minus, thereby generating the rotating magnetic field.

Advantages are a long lifespan, low maintenance, and high efficiency. Disadvantages are higher initial cost and more complicated motor speed controllers that typically require three Hall-effect sensors to get the stator-winding current phased correctly. That switching of the stator windings can result in "torque ripple"—periodic increases and decreases in the delivered torque. This type of motor is popular for smaller vehicles like electric bikes and scooters, and it's used in some ancillary automotive applications like electric power steering assist.

Permanent-Magnet Synchronous Motor (PMSM): Physically, the BLDC and PMSM motors look nearly identical. Both feature permanent magnets on the rotor and field windings in the stator. The key difference is that instead of using DC current and switching various windings on and off periodically to spin the permanent magnets, the PMSM functions on continuous sinusoidal AC current. This means it suffers no torque ripple and needs only one Hall-effect sensor to determine rotor speed and position, so it's more efficient and quieter.

The word "synchronous" indicates the rotor spins at the same speed as the magnetic field in the windings. Its big advantages are its power density and strong starting torque. A main disadvantage of any motor with spinning permanent magnets is that it creates "back electromotive force" (EMF) when not powered at speed, which causes drag and heat that can demagnetize the motor. This motor type also sees some duty in power steering and brake systems, but it has become the motor design of choice in most of today's battery electric and hybrid vehicles.

Note that most permanent-magnet motors of all kinds orient their north-south axis perpendicular to the output shaft. This generates "radial (magnetic) flux." A new class of "axial flux" motors orients the magnets' N-S axes parallel to the shaft, usually on pairs of discs sandwiching stationary stator windings in between. The compact, high-torque axial flux orientation of these so-called "pancake motors" can be applied to either BLDC or PMSM type motors.

AC Induction: For this motor, we toss out the permanent magnets on the rotor (and their increasingly scarce rare earth materials) and keep the AC current flowing through stator windings as in the PMSM motor above.

Standing in for the magnets is a concept Nikola Tesla patented in 1888: As AC current flows through various windings in the stator, the windings generate a rotating field of magnetic flux. As these magnetic lines pass through perpendicular windings on a rotor, they induce an electric current. This then generates another magnetic force that induces the rotor to turn. Because this force is only induced when the magnetic field lines cross the rotor windings, the rotor will experience no torque or force if it rotates at the same (synchronous) speed as the rotating magnetic field.

This means AC induction motors are inherently asynchronous. Rotor speed is controlled by varying the alternating current's frequency. At light loads, the inverter controlling the motor can reduce voltage to reduce magnetic losses and improve efficiency. Depowering an induction motor during cruising when it isn't needed eliminates the drag created by a permanent-magnet motor, while dual-motor EVs using PMSM motors on both axles must always power all motors. Peak efficiency may be slightly greater for BLDC or PMSM designs, but AC induction motors often achieve higher average efficiency. Another small trade-off is slightly lower starting torque than PMSM. The GM EV1 of the mid-1990s and most Teslas have employed AC Induction motors, despite skepticism about an EV revolution in some quarters.

Reluctance Motor: Think of "reluctance" as magnetic resistance: the degree to which an object opposes magnetic flux. A reluctance motor's stator features multiple electromagnet poles—concentrated windings that form highly localized north or south poles. In a switched reluctance motor (SRM), the rotor is made of soft magnetic material such as laminated silicon steel, with multiple projections designed to interact with the stator's poles. The various electromagnet poles are turned on and off in much the same way the field windings in a BLDC motor are. Using an unequal number of stator and rotor poles ensures some poles are aligned (for minimum reluctance), while others are directly in between opposite poles (maximum reluctance). Switching the stator polarity then pulls the rotor around at an asynchronous speed.

A synchronous reluctance motor (SynRM) doesn't rely on this imbalance in the rotor and stator poles. Rather, SynRM motors feature a more distributed winding fed with a sinusoidal AC current as in a PMSM design, with speed regulated by a variable-frequency drive, and an elaborately shaped rotor with voids shaped like magnetic flux lines to optimize reluctance.

The latest trend is to place small permanent magnets (often simpler ferrite ones) in some of these voids to take advantage of both magnetic and reluctance torque while minimizing cost and the back EMF (or counter-electromotive force) high-speed inefficiencies that permanent-magnet motors suffer.

Advantages include lower cost, simplicity, and high efficiency. Disadvantages can include noise and torque ripple (especially for switched reluctance motors). Toyota introduced an internal permanent-magnet synchronous reluctance motor (IPM SynRM) on the Prius, and Tesla now pairs one such motor with an AC induction motor on its Dual Motor models. Tesla also uses IPM SynRM as the single motor for its rear-drive models.

Electric motors may never sing like a small-block or a flat-plane crank Ferrari. But maybe, a decade or so from now, we'll regard the Tesla Plaid powertrain as fondly as we do those engines, even as industry leaders note that mainstream adoption faces hurdles, and every car lover will be able to describe in intimate detail what kind of motors it uses.
 

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