SPECTRUM: Exposing the Power Vampires in Self-Driving Cars

800px-Waymo_Chrysler_Pacifica_in_Los_Altos,_2017

Drag from rooftop sensors makes Waymo’s self-driving minivan an energy hog. Photo: Wikimedia/Dllu

By driving smarter, autonomous cars have the potential to move people around and between cities with far greater efficiency. Estimates of their energy dividends, however, have largely ignored autonomous driving’s energy inputs, such as the electricity consumed by brawny on-board computers.

 

First-of-a-kind modeling published today by University of Michigan and Ford Motor researchers shows that autonomy’s energy pricetag is substantial — high enough to turn some autonomous cars into net energy losers.

“We knew there was going to be a tradeoff in terms of the energy and greenhouse gas emissions associated with the equipment and the benefits gained from operational efficiency. I was surprised that it was so significant,” says to Greg Keoleian, senior author on the paper published today in the journal Environmental Science & Technology and director of the University of Michigan Center for Sustainable Systems.

Keoleian’s team modeled both conventional and battery-electric versions of Ford’s Focus sedan carrying sensing and computing packages that enable them to operate without human oversight under select conditions. Three subsystems were studied: small and medium-sized equipment packages akin to those carried by Tesla’s Model S and Ford’s autonomous vehicle test platform, respectively, and the far larger package on Waymo’s Pacifica minivan test bed [photo above].

For the small and medium-sized equipment packages, going autonomous required 2.8 to 4.0 percent more onboard power. This went primarily to power the computers and sensors, and secondarily to the extra 17-22 kilograms of mass the equipment contributed.

Sources of added energy consumption for Ford Fusion

Sources of added energy consumption in Ford Fusion’s autonomy system. Credit: University of Michigan

However, autonomy’s energy bill ate up only part of the overall energy reduction expected from the autonomous vehicles’ ability to drive smarter driving — such as platooning of vehicles through intersections and on highways to cut congestion in cities and aerodynamic drag on the highway. As a result the modeled Ford sedans still delivered a 6-9 percent net energy reduction over their life cycle with autonomy added, and promised a comparable reduction in greenhouse gas emissions.

EV and gas models offered comparable results. Adding equipment was less burdensome for the EVs, which provided extra power for the processors and sensors more efficiently than a gas vehicle. But autonomy delivered a slightly larger net energy reduction in the gas vehicles, whose relatively inefficient drivetrains should benefit more from smart driving.

In contrast adding the large Waymo equipment package yielded a comparatively dark picture for the modeled EVs and gasoline-fueled sedans. The larger equipment increased net energy consumption on the Ford sedans by 5 percent, thanks mostly to the aerodynamic drag induced by its rooftop sensors.

Keoleian says this modeling result likely overstates real impacts from future autonomous vehicles, which he expects will manage to streamline even substantial sensors arrays. What concerns him more is the likelihood that all of the modeled packages understate power consumption by future autonomous driving subsystems.

For instance, Keoleian says future autonomous vehicles may employ street maps of far higher resolution than those used today to ensure the safety of pedestrians, cyclists and other drivers. In fact, real-time updating of high-definition maps by autonomous cars is one of the applications pushing the development of next-generation 5G wireless data networks.

Higher-bandwidth data transmission via today’s 4G network could boost power consumption by onboard computers by one third or more according to Keoleian and his coauthors. It is premature, they write in today’s study, to judge the power consumption associated with 5G.

Another concern for Keoleian are the indirect effects of introducing autonomous vehicles. By making driving more convenient, for example, smart cars could encourage longer commutes. “There could be a rebound effect. They could induce travel, adding to congestion and fuel use,” says Keoleian.

Such indirect effects of smart cars could either slash energy consumption from driving by 60 percent, or increase it by 200 percent, according to a 2016 study by the U.S. National Renewable Energy Laboratory. Guiding the technology’s development to avoid an energy demand explosion, says Keoleian, will require a lot more study.

This post was created for Cars That Think, IEEE Spectrum’s blog about the systems making cars smarter, more entertaining, and ultimately, autonomous.

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U.S. Tech Titans Vow to Resist Trump’s Paris Pullout

U.S. President Donald Trump’s Rose Garden declaration yesterday that he will pull the country out of the Paris Agreement on climate change painted the United States as an economic victim, swindled into an “unfair” deal by the global community. He is right that the world is united: Nearly 200 countries back the 2015 Paris deal, with only Syria, Nicaragua and now the U.S. opting out. But fact checkers had a field day with Trump’s justification: his claim (against all evidence to the contrary) that the treaty imposes “onerous energy restrictions” on the U.S. that would beget “lost jobs, lowered wages, shuttered factories, and vastly diminished economic production.”

Nicaragua opted to stay out because it viewed the treaty’s reliance on voluntary national pledges rather than binding greenhouse gas reduction targets as “a path to failure” that would allow human-caused global warming in this century to surpass the agreed limit of 1.5 to 2 degrees Celsius. Trump said yesterday he would keep the U.S. in the Paris deal only if he can renegotiate it to be weaker still, though his language belied a lack of conviction. “If we can, that’s great. If we can’t, that’s fine,” equivocated Trump.

The President’s retreat from one the great technological challenges of the 21st Century marked a sad day for America’s innovation leaders, and a breaking point for Elon Musk. The tech titan behind such fast-growing engineering powerhouses as Tesla Motors and SpaceX insisted on Tuesday that he had worked mightily, both directly with the President and through his membership on three Presidential economic councils, to convince Trump to stick with Paris. Within minutes of Trump’s speech yesterday, Musk tweeted that he was pulling himself from Team Trump:

Elon Musk tells Trump what he really thinks.

Musk had considerable company. A sweeping set of U.S. innovators, mayors, governors, and business leaders spoke up yesterday, vowing to stick with the goals of the Paris Agreement even if the federal government does not. They have another three years to work on Trump’s stance, because the treaty’s rules impose at least a three year wait for a signatory to pull out. Continue reading

Visualizing Donald Trump’s ‘Who knew?!’ Climate Policy Moment

U.S. President Donald Trump called health insurance an “unbelievably complex subject” when Congress was debating health care in February. “Nobody knew health care could be so complicated,” said Trump as Republicans in Congress struggled to find consensus on how to repeal and replace the Affordable Care Act. Given developments in Washington, D.C., over the past week, he could soon be issuing similar tweets about unimagined intricacies in energy policy—intricacies with critical implications for technology developers.

Last week’s main affair in Washington, of course, was Trump’s firing of FBI director James Comey, and the ensuing ‘political firestorm’. But two big energy issues were also playing out, exposing policy rifts among Republicans—cracks that that could ultimately shift the course of U.S. and global policy. Continue reading

Commentary: Photo Ops with Coal Miners Offer No Substitute for Fact-based Climate Policy

Harry Fain, coal loader. Inland Steel Company, Floyd County, KY. 1946. Photo: Russell Lee

President Donald Trump surrounded himself with coal miners at the EPA yesterday as he signed an executive order calling for a clean sweep of all federal policies hindering development of fossil fuel production in the United States. The order’s centerpiece is an instruction to federal agencies to cease defending EPA’s Clean Power Plan and thus, according to Trump’s rhetoric, revive coal-fired power generation and the miners who fuel it.

The electric power sector, however, responded with polite dismissal.

What separates President Trump and some of his top officials from power engineers and utilities? The latter operate in a world governed by science and other measurable forces. Unlike President Trump, scientists, engineers, and executives suffer reputational and financial losses when they invent new forms of logic that are unsupported by evidence. And a world of fallacies underlies the President and his administration’s rejection of climate action. Continue reading

Trump Dumps Climate Science and Innovation in 2018 Budget Blueprint

NASA’s telescope on DSCOVR snapped a solar eclipse over South America in February

Al Gore didn’t really claim to invent the Internet in 1999, but he did champion a NASA mission that installed a deep space webcam pointed at Earth in 2015. And yesterday President Trump put a bullseye on that mission. Or, rather, on part of it. Trump’s 2018 budget blueprint asks Congress to defund the Earth-facing instruments on the Deep Space Climate Observatory (DSCOVR). Its sensors tracking magnetic storms emanating from the Sun would keep doing their jobs.

Selectively deep-sixing well-functioning instruments on a satellite 1.5 million kilometers from Earth is one of the stranger entries in President Trump’s first pass at a budget request. But it fits a pattern: Throughout the document programs aimed at comprehending or addressing climate change take deep cuts, even where there is no obvious fiscal justification. Continue reading

The Natural Gas Accounting Gap

Last month the U.S. EPA admitted it was way off in its estimate of how much methane producers leak into the atmosphere in the process of wresting natural gas from the ground and piping it across the continent. It’s a big deal since methane is a far more potent greenhouse gas than carbon dioxide and likely responsible for a substantial fraction of the climate change we’re already experiencing. And it’s been a long time coming. For many years now methane measurements by airplanes and satellites have strongly suggested that methane emissions from the oil and gas patch could be double what EPA figures captured.

Today the online earth observation pub Earthzine has my take on an unusual research project that helped convince EPA — and the industry — to change their tune on methane emissions. Take me to the article…

NASA Launches its First Carbon-Tracking Satellite

Photo: Bill Ingalls/NASA

Photo: Bill Ingalls/NASA

It’s been a rough birthing process for NASA’s Orbiting Carbon Observatory (OCO) satellite program, which promises global tracking of carbon dioxide entering and leaving the atmosphere at ground level. Five years ago the first OCO fell into the Antarctic Ocean and sank, trapped inside the nose cone of a Taurus XL launch vehicle that failed to separate during launch. The angst deepened yesterday when NASA’s Jet Propulsion Laboratory (JPL) scrubbed a first attempt to launch a twin of the lost $280-million satellite, OCO-2, after sensors spotted trouble with the launch pad’s water-flood vibration-damping system less than a minute before ignition.

But this morning OCO’s troubles became history. At 2:56 a.m. PDT a Delta II rocket carrying the OCO-2 satellite roared off the pad at Vandenberg Air Force Base in California. According to JPL, the OCO separated from the Delta II’s second stage 56 minutes later and settled into an initial 690-kilometer-high orbit. If all goes well it will maneuver into a final 705-km orbit over the next month, putting it at the head of an international multi-satellite constellation of Earth-observing satellites known as the A-Train. Continue reading