SPECTRUM: Exposing the Power Vampires in Self-Driving Cars

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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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Bomb Cyclone Exposes Perry’s Subsidy Fallacy

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Pilgrim Nuclear Power Plant: Looks good on a sunny blue sky day, but didn’t weather the storm. Photo: NRC

Extreme weather events have knocked both nuclear and coal-fired power plants offline in just the past six months, undercutting the Trump Administration’s argument that subsidizing these aging energy generators is crucial for bolstering grid stability.  The latest failure came late last week when Winter Storm Gregory forced a nuclear plant in New England offline, ratcheting up the challenge facing grid operators amidst the “bomb” cyclone’s high winds and freezing temperatures. Continue reading

Solar Microgrids May Not Fix the Caribbean’s Devastated Power Systems

After the destruction inflicted across the Caribbean by hurricanes Harvey, Irma, and Maria, renewable energy advocates are calling for a rethink of the region’s devastated power systems. Rather than simply rebuilding grids that delivered mostly diesel generation via damage-prone overhead power lines, renewables advocates argue that the island grids should leapfrog into the future by interconnecting hundreds or thousands of self-sufficient solar microgrids.

“Puerto Rico will lead the way for the new generation of clean energy infrastructure. The world will follow,” asserted John Berger, CEO for Houston-based solar developer Sunnova Energy in a tweet before meeting in San Juan with Puerto Rico Governor Ricardo Rosselló this week. Rosselló appears to be on board, inviting Elon Musk via tweet to use Puerto Rico as a “flagship project” to “show the world the power and scalability” of Tesla’s technologies, which include photovoltaic (PV) rooftops and Powerwall battery systems.

Some power system experts, however, say the solar-plus-batteries vision may be oversold. They say that the pressing need to restore power, plus equipment costs and other practical considerations, call for sustained reliance on centralized grids and fossil fuels in the Caribbean. “They need to recover from the storm. Unfortunately I think the quickest way to do that is to go back to how things were before,” says Brad Rockwell, power supply manager for the Kauaʻi Island Utility Cooperative that operates one of the most renewable-heavy grids in the U.S. Continue reading

NATURE Scientists Get Political on Climate

By Peter Fairley for Nature / October 11 2017

It’s moving day at the Legislative Assembly of British Columbia on a sunny summer morning in Victoria, Canada, and climate scientist-turned politician Andrew Weaver is battling to retain an expansive leather sofa for his new basement office. Just a few weeks earlier, in May 2017, thousands of people in and around Victoria cast their votes for the British Columbia Green Party, which Weaver leads, growing the caucus from his one lonely seat to three. The wider of the office’s sofas, he explains, will be crucial during long nights of debate and voting. “This is the one you can sleep on. And we need that.”

Three seats in an 87-seat legislature might sound modest, but it’s enough to make Weaver — a professor at the University of Victoria — into a political kingmaker. The incumbent Liberal Party and the opposition New Democratic Party (NDP) each garnered fewer than half of the seats, giving Weaver’s Green Party the balance of power. Weaver exercised his new-found influence in the weeks after the election to remove Christy Clark, the Liberal premier of British Columbia, who had championed fossil fuels and neglected climate policy. He negotiated climate-friendly terms with the NDP to install John Horgan as the party’s first premier in 16 years.

Weaver is an internationally recognized pioneer of models that represent Earth’s physical systems at a modest resolution, facilitating the simulation of climate over tens of thousands of years. His ascent from academic to political power broker is a far cry from the attacks on climate scientists that are under way in the United States. But there are US researchers who dare to dream that they too can tilt the political balance. In fact, dozens have declared the intent to run for local, state or national office, promising to reverse the dismissal of climate change and other anti-science positions espoused by US President Donald Trump’s administration and other Republican Party leaders.

… READ ON AT NATURE.COM

Floating Wind Turbines on the High Seas

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Norwegian oil and gas giant Statoil positions 6-megawatt turbines off the coast of Scotland for the world’s first floating wind farm. Photo: Roar Lindefjeld/Woldcam/Statoil

The world’s first wind farm employing floating turbines is taking shape 25 kilometers off the Scottish coast and expected to begin operating by the end of this year. New research by atmospheric scientists at the Carnegie Institution for Science in Stanford, Calif. suggests that the ultimate destination for such floating wind farms could be hundreds of kilometers out in the open ocean. The simulations, published today in the Proceedings of the National Academy of Sciences, show that winds over the open ocean have far greater staying power than those over land.

Wind power generation is obviously contingent on how fast and how often winds blow. But only over the past decade have scientists and wind farm developers recognized that the winds measured prior to erecting turbines may not endure. For one thing, dense arrays of wind turbines act as a drag on the wind, depleting local or even regional wind resources. Continue reading

Has the UN Climate Assessment Process Become Obsolete?

Peter Fairley for InsideClimate News Sept 8, 2017

The sweeping multi-year assessments produced by the Intergovernmental Panel on Climate Change set the gold standard for global scientific consensus on how humanity is altering Earth’s climate, and how to anticipate and minimize those changes. Some top climate scientists, however, are reviving a harsh critique of the IPCC’s assessment process, saying that it takes too long and that the delay could actually be creating an excuse for political inaction.

That process is moving forward this week with little sign of changing as scientists and government officials meet in Montréal to nail down a detailed blueprint for the sixth assessment since the IPCC’s creation in 1988. On Wednesday, IPCC Chair Hoesung Lee called the meeting the “most important” in the production cycle for what will become IPCC Sixth Assessment Report—a cycle that began in 2015 and will not conclude until 2022.

That seven-year schedule is simply unacceptable for a document that is “relied on by countless decision makers around the world every day,” said Katharine Hayhoe, an atmospheric scientist and co-director of the Climate Science Center at Texas Tech …

… read on at ICN

Rumble Royale: Can the U.S. Grid Work With 100% Renewables?

Four Days in 2055: Dynamic heat and power supply in the mid-century wind, water and sunlight-fuelled Continental U.S. simulated by Stanford’s Mark Jacobson. Credit: ASU/PNAS

A battle royale between competing visions for the future of energy blew open today on the pages of a venerable science journal. The conflict pits 21 climate and power system experts against Stanford University civil and environmental engineer Mark Jacobson and his vision of a world fuelled 100 percent by renewable solar, wind, and hydroelectric energy. The criticism of his “wind, water and sun” solution and an unapologetic rebuttal from Jacobson and three Stanford colleagues appear today in the Proceedings of the National Academy of Sciences (PNAS).

The critics enumerate what they view as invalid modeling tools, modeling errors, and “implausible and inadequately supported assumptions” in a projection of the mid-century U.S. energy supply that Jacobson and his coauthors published in PNAS in 2015. “The scenarios of [that paper] can, at best, be described as a poorly executed exploration of an interesting hypothesis,” write the experts, led by Christopher Clack, CEO of power grid modeling firm Vibrant Clean Energy.

Clack says their primary goal is accurate science, the better to equip policymakers for critical decisions: “We’re trying to be scientific about the process and honest about how difficult it could be to move forward.”

The text and statements by Clack’s coauthors question Jacobson’s evaluation of competing energy technologies, and specifically his rejection of two non-renewable energy options: fossil fuel power plants equipped to capture their own carbon dioxide pollution and nuclear reactors.

Jacobson calls Clack’s attack, “the most egregious case of scientific fraud I have encountered in the literature to date.”

In fact, while both sides claim to be objectively weighing the energy options, the arguments and backgrounds of the protagonists belie well-informed affinities for various energy sources (and informed biases against others). As sociologists of science would say, their choice of data and their reading of it reflects hunches, values, and priorities.

Consider Clack’s coauthor Ken Caldeira, a climate scientist at the Carnegie Institution for Science. Caldeira’s press release broadcasting their critique argues that removing carbon dioxide from the U.S. power supply is a massive job demanding the biggest tool box possible: “When you call a plumber to fix a leak, you want her to arrive with a full toolbox and not leave most of her tools at home,” says Caldeira.

The same document then abandons this technology-agnostic tone to call out nuclear energy and carbon capture as technologies that “solving the climate problem will depend on.” And Caldeira has appealed for deploying a new generation of nuclear reactors which he and other nuclear boosters such as former NASA scientist Jim Hansen say are needed because renewables “cannot scale up fast enough.” Continue reading