Time to Rightsize the Grid?

Does Size Matter Source CarrerasLast week a team of systems scientists known for counter-intuitive insights on power grids delivered a fresh one that questions one of the tenets of grid design: bigger grids, they argue, may not make for better grids. University of Iowa electrical engineering professor Ian Dobson and physicists David Newman and Ben Carreras make the case for optimal sizing of power grids in last week’s issue of the nonlinear sciences journal Chaos.

In a nutshell, the systems scientists use grid modeling to show that grid benefits such as frequency stabilization and power trading can be outweighed by the debilitating impacts of big blackouts. As grids grow larger, they become enablers for ever larger cascading blackouts. The Northeast Blackout of 2003 was a classic case. From a tripped line in northern Ohio, the outage cascaded in all directions to unplug more than 50 million people from western Michigan and Toronto to New York City.

This week’s findings are more conceptual, however, than some news outlets would have us believe. NBC News, in an online article entitled Researchers Suggest It’s Time to Downsize Power Grid, misjudged the Chaos report as a call to break up the dual grids that interconnect most of eastern and western North America. “It’s not possible to really make that statement,” says Carreras, who runs Oak Ridge, TN-based consulting firm BACV Solutions and is a visiting professor at Madrid’s Universidad Carlos III.

NBC misinterpreted Carreras et al’s simulations showing that grids with just 700-1000 nodes (over 15 times smaller than North America’s big grids) maximize interconnection benefits while minimizing blackout costs (see above chart). The researchers say this could indicate that some real grids are too large, but there are two big reasons to be cautious about drawing conclusions.

Carreras stresses that the model nodes are not necessarily representative of those on a real grid. Many of the group’s simulations, for example, use scale models of the Western grid in which each node in the model represents, on average, 10 nodes on the real grid.

Newman, a physics professor at the University of Alaska in Fairbanks, notes that the specific models used in this Chaos study were idealized, homogeneous systems. As such, he says, they bear little resemblance to the heterogeneity of real grids with their diversity of voltage levels, branching patterns and other features. “700-1000 nodes was the optimal size for the artificial network we had constructed,” says Newman.

Media hype is a problem that has dogged this team of system scientists since they gained notoriety over a decade ago by identifying cascading failures as an innate feature of power grids. Their simulations, which I covered in a Spectrum cover story ten years ago, show that economic pressure to maximize return on investment loads power grids to levels that leave them at heightened risk of costly blackouts.

The researchers delivered a complex systems view of blackouts that they hoped would spur novel thinking about the costs and benefits in grid design, and novel approaches to blackout prevention. But their message was often misinterpreted as an attack on the quality of grid engineering, or an argument that trying to prevent blackouts was futile.

Carreras et al argue that this week’s report has important conceptual value, if one gets beyond the hype. For one thing, blackout risks should be factored into the cost-benefit calculation when grid planners consider expanded interconnection. This could be applicable in developing countries as well as in Europe, which recently expanded its grid to include Turkey’s and is considering extensions to North Africa and Russia.

It’s also possible that grid design could be engineered to enable extended interconnection without expanding cascading blackout risk. Newman points to the possibility that weak links could be deliberately placed within grids to confine cascading blackouts to their region of origin. The team’s next step, says Newman, is to study just that possibility by simulating and optimizing heterogeneous networks.

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

Sniffing Gas: White House Taps ARPA-E to Boost Methane Detection

Gasbot 2.0. Photo: Victor Hernandez

Gasbot photo: Victor Hernandez

In this month’s issue of IEEE Spectrum we spotlight the methane emissions overlooked by the U.S. EPA’s greenhouse gas inventory, and the satellite-based detector launching next year to map this “missing methane.” Last week the White House acknowledged EPA’s missing methane problem, and laid out a strategy to combat it. While promising to improve EPA’s inventory, including more use of top-down methane measurement, the White House also promised federal investment in ground-based methane sensing to plug leaky natural gas systems thought to be the source of much of the missing methane.

Action can’t come soon enough according to the Intergovernmental Panel on Climate Change (IPCC), which on Monday unveiled its latest report onClimate Change Impacts, Adaptation, and Vulnerability. The IPCC said “widespread and consequential” impacts are already visible and world leaders have only a few years to change course to avoid catastrophic warning. Methane is a major contributor according to the scientific body’s update on the physical basis for climate change, released last fall, which deemed methane to be up to 44 percent more potent as a warming agent than previously recognized.

The White House says that the U.S. Department of Energy’s ARPA-E high-risk energy R&D fund will contribute by seeking to improve natural gas sensors, which are presently sensitive or cheap but not both. ARPA-E is preparing a new funding program that the White House says will “deliver an order-of-magnitude reduction on the cost of methane sensing, thus facilitating much wider deployment throughout all segments of natural gas systems.”

One contestant for funding could be robotic systems such as the Swedish-developed Gasbot profiled by Spectrum last year. Gasbot, a project from Sweden’s Örebro University, uses a mobile robot from Kitchener, Ont.-basedClearpath Robotics equipped with a laser-based remote gas sensor to map methane concentrations across a potential leak site. Orebro doctoral student Victor Hernandez says the Gasbot team has implemented improvements sinceSpectrum‘s coverage, including the addition of an anemometer to help determine where detected emissions are coming from.

Using a robot might reduce labor costs and accelerate the process of mapping a site, such as a natural gas plant or a landfill, and Hernandez says a market survey conducted last year has confirmed commercial interest in Gasbot. But Örebro’s package doesn’t come cheap in its present incarnation. The gas sensor alone costs about €10 000 (US $13 760), he says, and the Clearpath A-200 robot is another $12 000 or so.

Another contestant could be the laser science research group at Rice University, in Houston, which has recently demonstrated two novel strategies for building compact, sensitive and potentially low-cost methane detectors. The best developed relies on recently miniaturized mid-infraredquantum cascade lasers and cheap piezo-electric devices to detect the laser-excited heating of traces of methane gas—traces as thin as 13 parts per billion (ppb) according to group leader Frank Tittel, a professor of electrical engineering. His newer system uses advanced optics to more than double the methane sensitivity.

Tittel’s group has already proven its devices at a Houston landfill through a NASA program designed to calibrate space-based measurements of methane and other pollutants. He projects that the piezo-electrically tuned sensor could be scaled down and mass produced to deliver a $1000 system the size of a smart phone. The key, says Tittel, is mass production of the lasers, which currently cost $12 000.

Tittel says his group has teamed up with Newton, N.J.-based Thorlabs, which makes the required quantum cascade lasers as well as the electronics, mechanical stabilizers, and optics to build an integrated product.

Thorlabs appears to be keen. The company presented at an ARPA-E methane technology workshop last year, and declared its intention to “grow the [mid-infrared laser] market by reducing component costs.”

Message to missing methane: You may soon have nowhere to hide.

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

Satellites and Simulations Track Missing Methane

In the April 2014 issue of IEEE Spectrum:

Methane emissions from oil and gas extraction, herding livestock, and other human activities in the United States are likely 25 to 75 percent higher than the U.S. Environmental Protection Agency currently recognizes, according to ameta-analysis of methane emissions research published recently in Science. While experts in remote sensing debate the merits of this and other recent challenges to the EPA’s numbers, definitive answers are already on order via a high-precision Earth observation satellite to be launched next year.

The intensifying methane emissions debate has profound implications for climate and energy policy. Natural gas consumption is rising, and methane’s global warming impact is more than 30 times as much as that of carbon dioxide, molecule for molecule, and second only to carbon dioxide’s in today’s net climate impact …

click to read on

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

EC Sees Heavy Pricetag to UK Nukes Plan

UK prime minister David Cameron at Hinkley Point

UK prime minister David Cameron at Hinkley Point

Government incentives for a pair of proposed nuclear reactors could cost U.K. taxpayers as much as £17.62 billion, thus exceeding the reactors’ projected cost. The EC figure is a preliminary estimate included in an initial report to London published on Friday by European Commission competition czars. The letter notifies the British government that—as we predicted in December—Brussels is launching a formal investigation to assess whether the subsidies violate European state aid rules.

The preliminary findings suggest that the U.K. and E.C. are on a collision source. As the Financial Times summed it up this weekend: “The severity of [the EC's] initial concerns will cast a shadow over government hopes to win approval for the deal.”

Continue reading

Broken Bats: Wind Power and the Damage Done

Last year, IEEE Spectrum profiled an ultrasonic alert for wind farm operators designed to let them know when bats are nearing their turbines. The potentially bat-saving technology can’t be ready soon enough according to this week’s issue of the journal Bioscience. University of Colorado ecologist Mark Hayes estimates that at least 600 000 and possibly more than 900 000 bats were killed by wind turbines last year in the U.S.

Hayes’ report is a statistical reassessment of data on bat carcasses found at wind turbine sites. His figure lends credence to a March 2013 mortality estimate of 880 000 deaths per year by Sacramento-based ornithologist and consultant Shawn Smallwood. That figure was well beyond previous estimates, which had ranged as low as 33 000. “My estimates, using different methods and data, bracket Smallwood’s 888 000 estimate,” writes Hayes in an e-mail to Spectrum. Continue reading

Counting the Sins of Chinese SynGas

Heavy water use, threats of tainted groundwater, and artificial earthquakes are but a sampling of the environmental side effects that have tarnished North America’s recent boom in natural gas production via hydraulic fracturing or fracking. No surprise then that in European countries such as the U.K. that are looking to frack for cheap domestic gas, the environmental protesters often arrive ahead of the drill rigs.

But countries seeking fresh gas supplies could do far worse than fracking. So say Duke University researchers who, in today’s issue of the research journal Nature Climate Change, shine a jaundiced spotlight on China’s plans to synthesize natural gas from coal. Nine synthetic gas plants recently approved by Beijing would increase the annual demand for water in the country’s arid northern regions by over 180 million metric tons, the Duke team concluded, while emissions of carbon dioxide would entirely wipe out the climate-cooling impact of China’s massive wind and solar power installations. Continue reading