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.

According to the Bundesnetzagentur, unplanned outages left the average German consumer without electricity for 15.32 minutes in 2013, down from 15.91 minutes in 2012 and 21.53 minutes in 2006. The performance, using the power industry’s System Average Interruption Duration Index (SAIDI), affirms Germany’s place in the top five for grid reliability for European countries.

German grid reliability, meanwhile, far outstrips the best SAIDI results delivered by U.S. and Canadian utilities. The top quartile of SAIDI results captured by last year’s North American reliability benchmarking exercise by the IEEE Power & Energy Society, for example, had consumers without power for an average of 93 minutes — six times longer than outages experienced by the average German consumer.

What makes Germany’s grid reliability notable is the repeated insistence by critics of renewable energy that blackout risk is rising under the German Energiewende or ‘energy transition’. As Craig Morris, lead author of the Berlin-based German Energy Transition, writes this week: “The news may come as a surprise to international critics of the Energiewende.”

Morris highlights one critical piece published by the Washington, D.C.-based Institute for Energy Research on the day that the Bundesnetzagentur released its data. The free market, fossil fuel-oriented group argues that German laws driving the installation of relatively clean but intermittent energy sources such as wind turbines and solar panels have already caused a “destabilization of the grid.”

The outcome of the Energiewende, predicts the group, will be “a higher potential for blackouts.” As Morris’ post this week notes, the most likely reason for Germany’s grid reliability is the preponderance of underground lines in the distribution networks. Over 80 percent of Germany’s low-voltage lines and over 90 percent of its medium-voltage lines are underground. Other European countries scoring high on SAIDI have similar preponderance of underground distribution, including Denmark, Switzerland and the Netherlands, according to a December 2013 reliability assessment from the Brussels-based Council of European Energy Regulators.

For Germany to maintain its reliability, it may ultimately need a lot more lines. A December 2012 study by the Berlin-based German Energy Agency or DENA found that continued growth in renewables would require 135,000-193,000 kilometers of new lines by 2030, and the upgrading of another 21,000-25,000 km. Stephan Kohler, DENA’s CEO, raised doubts that distributors could handle that €27.5-42.5 billion investment, despite financing mechanisms provided by the Bundesnetzagentur to spur investment: “The Federal Network Agency legally mandated an attractive profit. However, our study reveals that in practice the profits from increasing integration of renewable energy systems … are not adequate for the distribution grid operators to survive.”

Upgrades are, however, proceeding at the transmission level. Germany’s transmission operators are planning a set of internal high-voltage direct current (HVDC) lines that are expected to help distribute wind power generated in the North to consumers in the South, and to help push excess solar generation in the opposite direction.

The controllability of those HVDC lines should also be a boon for Germany’s neighbors. North-South power flows regularly loop out of Germany’s grid and hitch a ride over neighboring transmission grids instead. That’s an added burden that Poland, in particular, doesn’t need. While German consumers enjoy the highest levels of reliability, those in neighboring Poland suffered through an average of 254 minutes of unplanned outages in 2012. In other words, Poland’s grid operators have all the work they need just managing their internal system challenges.

This post was created for Energywise, IEEE Spectrum’s blog on green power, cars and climate

Minnesota Finds Net Metering Undervalues Rooftop Solar

Utilities should be paying more for their customers’ surplus solar power generation according to a solar pricing scheme approved by Minnesota’s Public Utility Commission last month and expected to be finalized in early April. Minnesota’s move marks the first state-level application of the ‘value of solar’ approach, which sets a price by accounting for rooftop solar power’s net benefits, pioneered by the municipal utility in Austin, TX.

Minnesota is one of 43 U.S. states that requires utilities to pay retail rates for surplus solar power that their customers put on the grid. Utilities across the U.S. are fighting such net metering rules, arguing that they fail to compensate the utility for services that their grid provides to the distributed generator. So last year pro-solar activists and politicians in Minnesota called the utilities’ bluff, passing legislation tasking the state’s Department of Commerce with calculating the true value of rooftop solar power. Continue reading

German Parliament OKs Bold HVDC Grid Upgrade

Germany’s bold transmission plan is a go. The Bundesrat, Germany’s senate, has accepted the plan’s enabling legislation forwarded to it by the Bundestag (Germany’s parliament), according to the authoritative German Energy Blog. There is every reason to expect that the plan’s core element — four high-voltage direct current or HVDC transmission lines profiled by Spectrum last month — will get built.

That is good news for Germany’s grid and those of its neighbors. All are straining to manage powerful and variable flows from the wind turbines and solar panels that provided 12 percent of Germany’s power generation last year.

Elements of both the HVDC system design and the legislation should ease construction of the HVDC systems. On the design side, Germany’s transmission system operators have specified advanced converters whose ability to arrest and clear DC line faults will reduce the risk of running overhead lines. This means the HVDC lines can use existing rights-of-way used by AC lines. In fact, they can be hung from the same towers. Read the May 2013 story for extensive discussion of the advanced modular multilevel converters.

The enabling legislation, meanwhile, will simplify line permitting by making a federal court in Leipzig the only forum for legal disputes concerning the projects. Separate legislation passed by the Bundesrat and Bundestag makes  Germany’s federal networks regulator, the Bundesnetzagentur or BNetzA, the sole permitting authority for power lines that cross Germany’s state or national borders. These measures — for better or worse — cut out state-level officials that face greater pressure from local project opponents and may be more sympathetic to their concerns.

Add it all up and Germany is en route to become the first country with HVDC lines playing a critical role at the core of their power grid. It is arguably the first real challenge to AC’s century-plus reign as the top dog in power transmission since DC-advocate Thomas Edison lost the War of Currents. Tesla and Westinghouse may just be rolling over.

This post was created for Energywise, IEEE Spectrum’s blog on green power, cars and climate

Germany Jumpstarts the Supergrid

05OLGermanGridMap

Power Core: Spectrum’s infographic take on Germany’s HVDC transmission plans

New developments in high-voltage DC electronics could herald an epic shift in energy delivery

By Peter Fairley

Stuttgart is one of the last places you’d expect to find in a power pinch. This south German city’s massive automotive plants run 24-7 without a hiccup, efficiency measures have held industrial power consumption flat, and solar panels flash from atop its major buildings. But now all that is at risk. The country’s accelerated shift from nuclear power and fossil fuels to renewable resources, such as wind and solar, has exposed a huge gap in its transmission capacity. If they are to survive, Stuttgart’s factories—and power consumers across southern Germany—will need to import a lot more power from the north, and Germany’s grid is already at capacity.

To fill the gap, Germany is considering an aggressive plan that would push high-voltage direct current, or HVDC, from its conventional position on the periphery of AC grids to a central role. The primary reason is simple: For the first time, HVDC seems cheaper than patching up the AC grid. But Germany’s transmission planners also have another motivation: They want to provide as much performance and reliability as they can to an AC grid that’s already strained by excess wind power. For that, they’re considering implementing power electronics that are capable of doing something that’s never before been done on a commercial line: stop DC current in milliseconds flat.

Germany’s plan could mark the beginning of something much bigger: a “supergrid” of inter connected DC lines capable of transporting electricity on a continental scale, ferrying energy from North Sea turbines, dams in Scandinavia, or Mediterranean solar farms to wherever demand is greatest at that moment…

Published in the May issue of IEEE Spectrum. Read the story at Spectrum.com.

Supergrid Technology Beats Expectations

HVDC breaker Source AlstomAn industrial research consortium that is a who’s-who of the European power industry says development of technologies to produce high-voltage DC (HVDC) supergrids accelerated in 2012 — “surpassing expectations.” The assessment comes in the supergrids technology roadmap updated earlier this month by Friends of the Supergrid, whose members include power equipment suppliers such as Siemens, ABB and Alstom, as well as transmission system operators and renewable energy developers.

Summarizing the conclusions of an expert group within the International Council on Large Electric Systems — better known as CIGRE, its French acroynm — the Friends of the Supergrid says there is now no doubt as to the feasibility of HVDC networks ferrying renewable energy resources from wherever they are in surplus to wherever they are needed: “CIGRE Working Group B4–52 considered this question, specifically whether it was technically and economically feasible to build a DC Grid, and the answer was yes.” Continue reading

AC/DC 101

Much of your editor’s reporting in 2012 focused on the re-emergence of direct current or DC power — through pieces in IEEE Spectrum, Technology Review, and Power & Energy Magazine — and there is more in the works. Some of you, however, may still be wondering what DC power is and how it differs from the alternating current or AC power flowing from most electrical sockets. So here are some answers.

The questions were posed by Andrew Huang, a 9th grader at High Technology High School in Lincroft, NJ, who recently interviewed me for a history project on Nikola Tesla and Thomas Edison’s late-19th Century War of Currents. (Check out The Oatmeal’s Why Nikola Tesla was the greatest geek who ever lived for a rather tilted yet entertaining take on a key combattant in this epic tech tussle.)

What are some differences between the physics of AC and DC? Continue reading

Electrical Upgrade Prescribed for Japan’s Crimped Grid

An advisory body for Japan’s powerful Ministry of Economy, Trade and Industry (METI) has endorsed a tripling of the capacity to pass power between Japan’s otherwise estranged AC power grids: the 50-hertz AC grid that serves Tokyo and northeastern Japan, and the 60-hertz grid that serves western Japan. This frequency divide hascomplicated efforts to keep Japan powered since the March 2011 earthquake and tsunami — a task that keeps getting harder with the inexorable decline in nuclear power generation (at present just one of Japan’s 54 reactors is operating). Continue reading