Solar Power and Grid Stability: Scenarios and solutions

hawaii.gridx299Renewable 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!”

Understanding the IPCC’s Devotion to Carbon Capture

P1130803-3I’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

Germany’s Grid: Renewables-Rich and Rock-Solid

Grid graph German Energy TransitionLast Friday Germany’s grid regulator released the 2013 data for grid reliability, and the figures have renewable energy advocates crowing. The latest numbers (released in German) reveal no sign of growing instability despite record levels of renewable energy on the grid — 28.5 percent of the power supplied in the first half of 2014. In fact, Germany’s grid is one of the world’s most reliable. Continue reading

Renewables to Dethrone Nuclear Under French Energy Plan

After months of negotiation, the French government has unveiled a long-awaited energy plan that is remarkably true to its election promises. The legislation’s cornerstone is the one-third reduction in the role of nuclear power that President François Hollande proposed on the campaign trail in 2012.

Under the plan, nuclear’s share of the nation’s power generation is to drop from 75 percent to 50 percent by 2025, as renewable energy’s role rises from 15 percent today to 40 percent to make up the difference. That is a dramatic statement for France, which is the world’s second largest generator of nuclear energy, after the United States. France has a globally-competitive nuclear industry led by state-owned utility Electricité de France (EDF) and nuclear technology and services giant Areva. Continue reading

Amid Blackouts, India’s New Leader Vows 24-7 Power for All

Blackouts this week in New Delhi and surrounding states are providing a dramatic backdrop for a bold promise by India’s new prime minister, Narendra Modi, whose Hindu nationalist party swept to power in a landslide election last month. As a scorching heatwave drove power consumption beyond the grid’s capacity, Modi’s government vowed to deliver “round-the-clock power for all by 2022,” reports the Wall Street Journal.

That will be an awesome task. Nearly one-quarter of India’s 1.26 billion citizens lack grid access. And India’s utilities have struggled to keep up with demand from those who are connected. Power cuts are frequent. Continue reading

Floating Wind Turbines Headed for Offshore Farms

PrinciplePower.WindFloatFloating wind power is no longer science fiction. Promising results from five test platforms operating worldwide—including three in Japan—are turning into project plans for a first generation of floating wind farms. Industry analyst Annette Bossler, who runs Bremen, Maine-based Main(e) International Consulting, predicts that the number of test platforms will nearly double over the next two years and that commercialization is within site. “By 2018-2019 you will start to see the first really large-scale commercial use of floating platforms,” predicts Bossler.

Putting wind turbines on offshore platforms akin to those developed for the petroleum industry provides a means of exploiting high-quality offshore winds—which are stronger and more consistent than onshore winds—in waters too deep for today’s bottom-fixed foundations. Continue reading

Seattle’s Bullitt Center Shines

Online at Architectural Record:

The designers of Seattle’s Bullitt Center have overachieved. The designers set out to demonstrate that a six-story office building could generate all of the energy it needs, but after one year of operation, it is sending a sizable energy surplus to the local power grid, according to data released by its developer, the Bullitt Foundation.

Consumption is simply far lower than what its architects and engineers projected for the 52,000-square-foot building. Instead of using 16kBtu per square foot—half the energy-use intensity (EUI) of Seattle’s best-performing office building—consumption during its first year was just 10kBtu/sf …

read on