Renewable energy is often intermittent, and that variability presents a variety of challenges to power grids. The nature and magnitude of the challenges depends on the time frame — from fractions of a second to seasonal or even multiyear variations — as well as the nature of the grid itself. The latter is evident in two of my articles from last week looking at how seconds-to-minutes fluctuations in solar power complicate grid controllers’ efforts to maintain alternating current at the 60 hertz frequency and the roughly 110 volt power levels required by North American devices.
Fluctuating AC frequency stars in my Technology Review dispatch from the paradise of Kauai, where the island utility is riding an electrical roller coaster as it pushes solar towards 80 percent of peak power flows. Clouds form around the Hawaiian islands’ mile-high peaks and wreak havoc as they float over solar farms, eliminating three-quarters of their generation in less than a minute. On Kauai’s tiny island grid the resulting power supply dips are deep enough to slow down Kauai’s handful of diesel-fuelled generators, causing the AC frequency to crash below 60 hertz.
My story tracks the Kauai Island Electric Cooperative’s hitherto troubled experience with using batteries to smooth out the solar power flows. Discharging a first set of batteries to fill the solar power gaps burned out the battery cells.
Larger continental grids experience solar power quite differently, as I described last week in IEEE Spectrum. Fluctuating output from even the biggest solar farms has little impact on a big grid’s AC frequency, which is maintained by the collective momentum of literally hundreds of conventional power plants spinning in sync. However, fluctuating output from lots of small rooftop solar systems can cause gyrating voltage on a big grid’s local distribution lines.
My piece for Spectrum shows how California is empowering solar systems to solve the voltage problem. The inverters that turn each system’s DC output into AC power for the grid are being deputized to serve as miniature grid regulators that monitor and dynamically adjust the voltage levels on the local lines.
California’s ‘smart inverters’ mark an about-face in how grid operators think about distributed power generation, and are definitely a good-news story. As reader @etlipman commented: “You know exciting changes are afoot when regulators and utilities that have in the past perceived something as a nuisance are starting to see it as asset!”
I’ve delivered several dispatches on carbon capture and storage (CCS) recently, including a pictorial ‘how-it-works’ feature on the world’s first commercial CCS power plant posted this week by Technology Review and typeset for their January print issue. Two aspects of CCS technology and its potential applications bear further elaboration than was possible in that short text.
Most critical is a longer-term view on how capturing carbon dioxide pollution from power plants (and other industrial CO2 sources) can serve to reduce atmospheric carbon dioxide concentrations. Continue reading →
Bangalore street vendor with battery-powered light. Source: IBM Research India
Bangalore-based IBM Research India has a bright idea for keeping discarded lithium laptop batteries out of landfills: repurposing their cells as energy supplies for the powerless. The idea, presented at this weekend’s fifth annual Symposium on Computing for Development (DEV 2014) in San Jose, has passed a small proof-of-principle test run with Bangalore’s working poor. Continue reading →
Water recovery concept for CCS at GreenGen. Source: LLNL
In an intriguing footnote to their historic climate deal this month, Chinese President Xi Jinping and U.S. President Barack Obama called for demonstration of a hitherto obscure tweak to carbon capture and storage (CCS) technology that could simultaneously increase its carbon storage capacity and reduce its thirst for water. Such an upgrade to CCS holds obvious attraction for China, which is the world’s top carbon polluter and also faces severe water deficits, especially in the coal-rich north and west.
Context is everything in understanding the U.S.-China climate deal struck in Beijing by U.S. President Barack Obama and Chinese President Xi Jinping last week. The deal’s ambitions may fall short of what climate scientists called for in the latest entreaty from the Intergovernmental Panel on Climate Change, but its realpolitik is important.
Obama and Xi’s accord sets a new target for reductions in U.S. greenhouse gas emissions: 26-28 percent below 2005 levels by 2025. And for the first time sets a deadline for China’s rising GHGs to peak: 2030. This is potentially strong medicine for cooperation, when seen in the context of recent disappointments for global climate policy. Continue reading →
European leaders wrapped up a two-day climate summit in Brussels last week with a deal to cut the European Union’s total greenhouse gas emissions to 40 percent below 1990 levels. This would continue a downward trend – the EU is already on track to meet a 20 percent reduction from 1990 levels by 2020 – but the agreement is weak relative to Europe’s prior ambitions to confront climate change.
Investors in green tech pushed aggressively for the deal, seeking a longterm signal that the European market will continue to reward advances in energy efficiency and low-carbon energy production. The deal is also a shot in the arm for the Paris global climate talks, scheduled for December 2015, which will seek to achieve the decisive binding global targets for greenhouse gas reductions that failed to emerge from the 2009 Cophenhagen climate talks.
What the deal lacks is specificity and ambition regarding the mechanisms by which European countries are to achieve the carbon reduction. “Key aspects of the deal that will form a bargaining position for global climate talks in Paris next year were left vague or voluntary,” reported The Guardian. Continue reading →
Two-and-a-half years ago researchers at Chicago-based cyber security firm Infracritical set out to measure how many industrial control systems are openly exposed to the Internet. Their disquieting findings are up for discussion today at the 2014 ICS Cyber Security Conference in Atlanta.
Infracritical remotely identified over 2.2 million unique IP addresses linked to industrial control systems at energy-related sites including electrical substations, wind farms, and water purification plants. And they were still logging an average of 2,000-3,000 new addresses per day when they closed the count in January 2014.
“We never reached bottom,” says Infracritical cofounder Bob Radvanovsky, an expert in securing supervisory control and data acquisition (SCADA) systems. Continue reading →