vol 7, issue 11

Surviving Sandy - smart technologies help the recovery

19 November 2012
By Mark Venables
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A crew from Canada restores power in Oyster Bay, NY

Microgrids and smart meters proved their worth during the US power cuts

A man fixing an overhead power line

Restoring electricity in Bernardsville, New Jersey

When Hurricane Sandy struck the US power networks, new technologies stood up to the test and demonstrated their worth.

On 29 October, Hurricane Sandy unleashed colossal devastation on the USA's east coast. Amidst the destruction there were mass power outages, which at their height affected more than eight million users and lingered on for several weeks, hampering relief efforts.

Events like this are glimpses of the types of extreme weather we could be more vulnerable to in the future. As the devastation continues to reverberate, decision-makers are asking: How can we be better prepared?

It seems that not much can be done to protect overhead cables save for removing nearby trees. There are those who advocate burying cables underground, but that carries the burden of extra cost, along with the danger in coastal areas of highly corrosive salt water seeping into the pipeline system.

Other options include local or decentralised generation, which removes the risk of damage to the transmission network. This allowed some organisations to continue as usual during the blackout. Then there is the supposed resilience inbuilt into a smart grid which allows automation and the two-way communication with smart meters to isolate damaged sections of the grid.

Although the surging sea quickly retreated, it left behind a salty residue that hampered restoration efforts. "You can't just pump the seawater out," explained John McDonald, director of technical strategy and policy development at GE Digital Energy. "Dry salt is an electrical conductor. When it covers insulators in transformers, switches, and other equipment it can make electricity flash over and cause a short circuit. It's also corrosive."

Utility crews had to first pump out Sandy's brackish tide, spray the equipment thoroughly with fresh water, and dry it with powerful fans before they could turn the power back on. The same was true for New York's submerged subway tunnels.

"When the equipment is all washed and dry, only then can you energise it step by step, test the functions and make sure that it still works," McDonald said.

Many believe that the disruption might have been even more severe if it were not for the gradual introduction of microgrids in the transmission and distribution system. The storm highlighted what power engineers are fully aware of, namely the inherent weakness of a centralised electricity system, and spotlighted the benefits of distributed power generation.

Distributed generation

In numerous cases universities, hospitals and businesses kept their power supply even during the worst of the storm. Some used back-up generators, but true microgrids allow organisations to operate as islands independent of the grid for long periods.

"The two hurricanes on the east coast over the past two years could generate more interest in microgrid technologies," says Peter Asmus, an analyst at Pike Research. "Smart grids are about reacting to storms and limiting the number of power outages. Microgrids are about stopping power outages. These storms are going to build interest."

One organisation that benefitted from its investment in on-site generation is New Jersey's Princeton University. In normal operating conditions the campus gets its electricity from both the local grid and an on-site cogeneration facility that supplies electricity and steam for heat. During Hurricane Sandy, Princeton was able to switch off the grid and power part of the campus with about 11MW of local generation, according to a report in the Daily Princetonian. Several days after the storm and when local power was available, Princeton coordinated with local utility PSEG and reconnected to the grid, the report said.

Smart meters

As efforts to restore power dragged into a third week, one company was heralding the use of smart meters. Pepco, which serves Washington and parts of Maryland, used the two-way communication functionality of its smart meters to automatically locate power outages on its network. Once power was restored, the utility could also exploit the meters to verify service.

Smart meters find another supporter in McDonald. "If you have smart meters at homes, you know which customers are without electricity," he said. "A utility can mash the smart meter data with information from a distribution management system, an outage management system, and the geographic information system. These maps include the geographical coordinates of all the switches, poles, meters and other assets."

It also helps power companies and their customers stay in touch. "You can let the customer know that we know of the problem, that we have a crew on the way, and when we expect to have power restored," he said.

One common complaint about smart meters is that consumers pay for the upgrade yet see few benefits. In the case of better grid reliability, perhaps the argument for change has been undersold.

Forward planning

Planning tools that allow local authorities to see the possible local effects of climate change are vital to preparation yet notoriously difficult to achieve.

"As we see more extreme events like Sandy, the importance of assessing regional impacts grows," said modelling specialist Adam Schlosser, principal research scientist in the Centre for Global Change Science at MIT. "Our approach helps decision- and policymakers balance the risks, so they can better prepare for future impacts climate change might bring.

"Should we rebuild to better prepare for future storms? Or should we prepare for stronger and more frequent storms? There remains uncertainty and that implies risk. Our technique is developed with this in mind."

Researchers quantify the likelihood of many outcomes and add socioeconomic data, different emission levels and varying degrees of uncertainty. Their technique combines climate-model projections and analysis from the Coupled Model Intercomparison Project used by the Intergovernmental Panel on Climate Change, and the MIT Integrated Global System Modelling framework. The MIT framework is a combined computer model that integrates an economic, human system with a natural, earth system.

"This provides us with efficient capabilities to determine climate-change risks," Schlosser said.

Sandy is a grim reminder that repeated failures have not resulted in better protection from predictable power outages.

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