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.”

They could be right. Then again, expert sources they cite, such as the International Energy Agency, have consistently underestimated renewable energy growth. And identical scale-up critiques have also been well argued against nuclear energy and carbon capture and storage (CCS).

Jacobson makes some powerful arguments for walking away from those technologies in his PNAS papers. Nuclear liabilities cited by Jacobson include the threat of future Fukushima-like disasters, nuclear weapons proliferation facilitated by large-scale uranium enrichment, and the financial risks such as those that recently bankrupted Westinghouse. And, as he notes in his rebuttal, the International Panel on Climate Change has determined there is “robust evidence” and “high agreement” among experts validating these nuclear risks.

Jacobson’s rejection of CCS technology, meanwhile, may provide deeper insight on what makes him a magnet for academic attacks.

The main thing that soured Jacobson on CCS was his own pioneering work on the climate change impacts of black carbon, or soot. Fossil fuel plants that capture most of their CO2 still release soot that’s both a public health menace and an agent of climate change. In a 2001 paper in Nature on simulations of soot particles in the atmosphere, he controversially argued that soot in the air and on blackened snow and ice fields absorbs enough heat to make its climate impact second only to CO2. Sixteen years on, that view now enjoys strong support from the science community.

Jacobson subsequently turned his science on black carbon into political activism, helping to convince California regulators to deny low-carbon incentives to so-called “clean diesel” technology. A decade later that tech is in disarray—sullied by scandals over fraudulent tailpipe cleanup claims. European automakers long reliant on diesel technology are now abandoning it in favor of hybrids, as IEEE Spectrum reported in April.

His style, however, has not necessarily made him popular among climate scientists. Drew Shindell, a climate modeler at Duke University, describes Jacobson as a brilliant scientist with an unusual go-it-alone style that alienates some researchers.

Whereas most climate models are honed by large teams, composed of hundreds of scientists, Jacobson single-handedly constructed the GATOR-GCMM climate model that underpins his work—including the 2001 Nature and 2015 PNAS reports. Shindell says other climate models are also shared more freely and subject to much more independent validation than Jacobson’s. So when he claims that “his model is more complex and therefore better,” says Shindell, it “rubs people the wrong way.”

To Shindell, however, Jacobson’s outspokenness and solo style do not invalidate his work. In fact, he argues that raising important questions is Jacobson’s greatest contribution: “His work does prompt people to really look closely. That’s also a service to the community.”

Could something similar be playing out now in PNAS? Power experts can bristle at outsiders who offer novel approaches to their problems. In 2004 Spectrum profiled mathematical modelers—a power engineer and a pair of plasma physicists—who were drawing heavy fire for the unorthodox prediction that big blackouts are inevitable. That trio (Ian Dobson, Benjamin Carreras, and David Newman) endured years of derision and saw their research funding pulled. They ultimately triumphed by all but predicting the Southwest blackout of 2011, a story I documented for Discover magazine last year.

Jacobson and his PNAS coauthors similarly crafted their own unorthodox energy model—LOADMATCH—which sets a bold vision. While their critics mostly model power grids, Jacobson’s team used LOADMATCH to map out a 100-percent-renewable route to meeting all major energy needs in the Continental United States. The model replaces fossil fuels for heating and transportation with renewably-generated hydrogen and electricity, thereby tackling nearly all greenhouse emissions from fossil fuels rather than just the 35 percent from power plants.

Mark Jacobson. Photo: L.A. Cicero

The weakest point in Jacobson’s 2015 paper identified by his critics is a heavy reliance on hydropower plants, which serve as his simulated power grid’s backstop energy supply during long periods of weak sun and becalmed winds. This jumps out in the graph [above], which simulates total continental U.S. heat and power generation over four days in January 2055. Hydro turbines ramp up heavily each day after the sun sets, delivering as much as 1,300 gigawatts at their peak—a level that implies a 15-fold expansion in hydropower generating capacity.

Jacobson says the LOADMATCH code adds turbines to existing hydropower dams as required to prevent power outages. The reservoirs are untouched, and thus store the same amount of energy. But that energy is concentrated into those hours of the year when no other power source is available.

However, no such expansion is documented in the 2015 paper. Critic-in-chief Christopher Clack argues that it is a modeling error because, according his analysis, adding the required turbines at existing dams is not physically possible. And even if it were, he says, discharging the hydropower as described would impose unacceptable impacts on aquatic ecosystems and downstream water users. Invalidating that option, says Clack, means Jacobson’s scheme will cause blackouts: “The whole system breaks down.”

Jacobson admits the 2015 paper was “vague” on the hydropower upgrade but stands by its technical and economic viability. The environmental impacts, he says, reflect a cost that policymakers pursuing his roadmap would need to consider. All clean energy solutions will require tradeoffs, says Jacobson, noting that the low-carbon grid projection that made Clack’s reputation, a 2016 report in Nature Climate Change, calls for a much larger build-out of unpopular powerlines.

Jacobson also has alternative sources of backup power, such as adding turbines to more rapidly convert stored heat from solar thermal power plants into electricity. “We could increase [their] discharge rate by a factor of 3.5 to obtain the same maximum discharge rate of hydro, without increasing the [solar thermal plants’] mirror sizes or storage,” he says.

If you’re wondering where battery storage figures in all of this, it is yet another option—though one that both Jacobson and Clack deemed unnecessarily costly in their respective studies. Clack’s 2016 projections relied mostly on flexible natural gas power plants rather than dams or batteries to handle residual power demand—delivering a 78 percent reduction of power sector carbon emissions from 1990 levels by 2030 [see map below].

What is certain, from the darkening findings of climate science, is that climate change calls for a bold remake of the global energy system of the sort that both Clack and Jacobson have championed. Their respective visions certainly appear to have more in common than ever as the Trump Administration seeks to turn back the clock on grid engineering.

The U.S. power sector is bracing for the release of a power grid study ordered by President Trump on whether renewable energy installations degrade grid reliability by undermining continuously operated “baseload” nuclear and coal power plants. U.S. Energy Secretary Rick Perry’s memo commissioning the study states as fact that “baseload power is necessary to a well-functioning electric grid.”

Last week, the Rocky Mountain Institute’s Mark Dyson and Amory Lovins called out that “curious claim,” which they say, “has been thoroughly disproven by a diverse community of utilities, system operators, economists, and other experts that moved on from this topic years ago.” What the grid needs, they write, is flexibility, not baseload power plants.

The power industry is already moving in that direction. For example, flexibility was California utility PG&E’s central argument last year when it announced plans to shut down the Diablo Canyon nuclear plant when its reactor licenses expire in 2024 and 2025. The baseload plant was ill-suited, PG&E said, to help them manage the increasingly dynamic power flowing on California’s grid.

Dyson and Lovins’ prescription for the power grid community, meanwhile, is unity. As they titled last week’s post: “The grid needs a symphony, not a shouting match.”

Chris Clack’s 2016 U.S. power sector simulation slashes CO2 emissions 78% using a DC supergrid and gas-fired power to balance renewable energy. Source: Nature Climate Change

This post was created for Energywise, IEEE Spectrum’s blog about the future of energy, climate, and the smart grid

Can Synthetic Inertia from Wind Power Stabilize Grids?

p1110724As renewable power displaces more and more coal, gas, and nuclear generation, electricity grids are losing the conventional power plants whose rotating masses have traditionally helped smooth over glitches in grid voltage and frequency. One solution is to keep old generators spinning in sync with the grid, even as the steam and gas turbines that once drove them are mothballed. Another emerging option will get a hearing next week at the 15th International Workshop on Large-Scale Integration of Wind Power in Vienna: synthetic inertia.

Synthetic inertia is achieved by reprogramming power inverters attached to wind turbines so that they emulate the behavior of synchronized spinning masses.

Montréal-based Hydro-Québec TransÉnergie, which was the first grid operator to mandate this capability from wind farms, will be sharing some of its first data on how Québec’s grid is responding to disruptive events such as powerline and power plant outages. “We have had a couple of events quite recently and have been able to see how much the inertia from the wind power plants was working,” says Noël Aubut, professional engineer for transmission system planning at Hydro-Québec. Continue reading

Wind Could Provide Over 26% of Chinese Electricity by 2030

Last month I argued that the primary reason Chinese wind farms underperform versus their U.S.-based counterparts is that China’s grid operators deliberately favor operation of coal-fired power plants. Such curtailment of wind power has both economic and technical roots, and it has raised serious questions about whether China can rely on an expanding role for wind energy. New research published today appears to put those concerns to rest, arguing that wind power in China should still grow dramatically.

The report today in the journal Nature Energy projects that wind energy could affordably meet over one-quarter of China’s projected 2030 electricity demand—up from just 3.3 percent of demand last year.

In fact the researchers, from MIT and Tsinghua University, project that modest improvements to the flexibility of China’s grid would enable wind power to grow a further 17 percent. That, they argue, means that China’s non-fossil resources could grow well beyond the 20 percent level that China pledged to achieve under the Paris Climate Agreement. Continue reading

Solar Power Towers Aren’t the Avian Annihilators Once Thought

Solar power towers have had a reputation as alleged avian vaporizers since preliminary reports emerged in 2014 of birds being burned in mid-air as they flew through the intense photonic flux at California’s Ivanpah solar thermal plant. Their reputation was muddied even more during tests early this year at SolarReserve’s Crescent Dunes power tower in Nevada; the solar thermal plant just recently began producing power. California public radio station KCET reported that as many as 150 birds were killed during one six-hour test in January.

It is obviously upsetting to imagine birds ignited in the name of renewable energy. (KCET reporter Chris Clarke, who has tracked the issue since BrightSource Energy began building Ivanpah in the Mojave Desert, described burning birds as “beyond the pale” in a recent article suggesting that power towers may be finished in California.)

But, upsetting as any killing of birds is, avian mortality is a downside common to many modern human creations—including buildings, highways, and powerlines. The best data on bird mortality at Ivanpah, macabre as it might be, shows the death rate to be small and likely of little ecological significance.

Meanwhile, operational adjustments at both Ivanpah and Crescent Dunes are pushing avian impacts even further below levels that could threaten local bird populations. “The data does support a low level of avian mortalities and hopefully, through adaptive management and deterrence, it will go even lower,” says Magdalena Rodriguez, a senior environmental scientist with the California Department of Fish and Wildlife. Continue reading

Arizona Utility Blinks in Bitter Battle Over Rooftop Solar

Arizona’s biggest utility, Arizona Public Service, is withdrawing its bid to jack up monthly fees for rooftop solar users in its territory. The retreat, tendered last week to the Arizona Corporation Commission (ACC), capped an eventful month in the high-stakes battle between utilities and solar advocates that’s raging across Arizona rooftops. The party with the most bruises is not Arizona Public Service (APS), however, but the ACC itself. The elected body referees the state’s power markets, but all five of its commissioners now face accusations of bias that challenge their ability to fairly adjudicate the rooftop solar dispute.

Arizona’s solar dispute is hot, but not unique. Across the United States utilities are fighting to contain or eliminate “net metering” policies Continue reading

Storing Solar Energy: A great idea caught on contested ground

Adding energy storage to sites with rooftop solar power generation offers a range of potential benefits. A battery can help smooth out solar’s inherently variable supply of power to the local grid, and even keep buildings powered during blackouts. Consequently, power-conversion innovators are developing a host of new products designed to reduce the cost and improve the efficiency of integrated solar-storage systems.

Some analysts project a boom in the co-location of solar and energy storage. GTM Research, for example, foresees that co-located PV and storage will grow from $42 million in 2014 to more than $1 billion by 2018. However, the market is moving slower than it might thanks to a little-discussed regulatory roadblock in the United States.

According to Vic Shao, CEO for the Santa Clara, California-based energy storage startup Green Charge Networks, tightly integrating storage with photovoltaics in some key states—including Hawaii and California—runs afoul of the “net metering” rules by which PV owners earn lucrative retail rates for the surplus power they feed to the grid. Adding storage can disqualify solar systems for net metering, in which utilities can pay their owners wholesale power rates that are several times lower than retail. “That is obviously a pretty big problem for anybody considering solar. That could kill a lot of projects,” says Shao. Continue reading

European Grid Operators 1, Solar Eclipse 0

Solar forecast for March 20 via, with previous days' generation

Solar forecast for March 20 from, with prior days’ solar output

Weather forecasts calling for bright sun today across Europe drove up tensions in advance of the partial solar eclipse that blocked the sun’s rays and plunged much of the continent into a brief period of darkness this morning. Grid operators were bracing for record swings in solar power generation because of the celestial phenomenon. Some power distributors in Germany had warned of fluctuations in frequency, notifying customers and suggesting that they shut down sensitive equipment.

In the end, while clear weather made for some excellent eclipse viewing, the electrical story ultimately felt more like Monty Python’s radio coverage of the 1972 eclipse. As if audio coverage of a quintessentially visual event isn’t absurd enough, the Pythons closed their fictitious report in the ultimate anticlimax, as a sudden rainstorm swept in to spoil the solar spectacle. Europe’s interconnected power grid brought about an equally anticlimactic ending today by delivering rock-solid stability throughout the 2.5-hour eclipse. Continue reading