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Senate panel explores the EMP threat

2 June 2017

The danger to the electric grid and other infrastructure from solar storms and electromagnetic-pulse weapons is real, but its magnitude is debated.

Solar storm
This powerful coronal mass ejection, captured by the STEREO-A probe on 23 July 2012, came close to encountering Earth and endangering the electrical grid. Credit: NASA’s Scientific Visualization Studio

Every couple of years a congressional committee takes a look at the threat to the US posed by both naturally occurring geomagnetic disturbances (GMDs) and attacks with an electromagnetic pulse (EMP) generated by a nuclear weapon. On 4 May the Senate Committee on Energy and Natural Resources took its turn, hearing from witnesses who alternately sought to scare and reassure the lawmakers. Former House Speaker Newt Gingrich, for one, declared an EMP attack “one of the three great threats to our survival,” on par with cyberwarfare and nuclear weapons. “Here we are gambling our civilization,” he warned. “This is vastly bigger than 9/11.”

Henry Cooper, a former director of the Strategic Defense Initiative, called for the deployment of the Aegis antiballistic missile system in the Gulf of Mexico to address the threat of an EMP weapon carried aboard an orbiting satellite. He also advocated for the revival of space-based ballistic missile defenses­―such as the scheme involving a “brilliant pebbles” swarm of kinetic interceptor satellites―that were proposed during the Reagan-era Star Wars initiative.

A GMD is caused by a solar storm, such as a flare or coronal mass ejection; an EMP can be created by detonating a nuclear weapon miles above Earth’s surface. In 1989 a coronal mass ejection caused the blackout of Quebec’s grid for nine hours. A much bigger solar storm in 1859, known as the Carrington event, destroyed telegraph lines across the US and caused the aurora borealis to be visible as far south as Cuba. In 2012 NASA detected a solar storm that, had it occurred a week earlier, might have triggered a Carrington-like event.

In 2004 a congressional commission reported that a single EMP unleashed high above Omaha, Nebraska, would cripple half the nation’s economy. That commission, which was reinstated in 2008 and then again last year, wrote in its 2004 report that Russia, China, and North Korea were working to develop EMP weapons.

Taking measures to defend the grid against a space weather event wouldn’t be sufficient to guard against an EMP attack. Only the human-made variety produces the short-wavelength, high-energy RF burst known as E1, which can destroy electronics, including the supervisory-control and data-acquisition systems that govern the grid, fossil-fuel pipelines, and other critical infrastructure.

A low-frequency RF component, E3, is common to both an EMP and a GMD. It induces an electric field at Earth’s surface, which in turn causes currents in power lines that can damage or destroy transformers and other transmission equipment. Some experts have warned that a single EMP device could cause the failure of enough high-voltage transformers to create severe blackouts across broad regions of the nation. Gingrich took that view, saying that the knockout of as few as nine “nodal points” on the US grid could result in “catastrophic” blackouts from which “conceivably you couldn’t recover for years.”

A February report by the Electric Power Research Institute (EPRI) came to a different conclusion. Using recently developed models of the grid, the institute found that an EMP weapon would have only a marginal effect on bulk power transformers. Still, Robin Manning, EPRI vice president for transmission and distribution, told senators that other potential impacts on the grid, including the cumulative effects of the different EMP frequencies, had yet to be thoroughly investigated.

Cooper cast doubt on the reliability of the EPRI report. He pointed to a 20 April letter in which William Graham, who has chaired all the iterations of the EMP commission, wrote that the study had been written in cooperation with “Obama administration holdovers” at the Department of Energy. Graham charged that the report “grossly underestimates the nuclear EMP threat.”

The FY 2017 defense authorization act instructs the Department of Homeland Security to review the risks and consequences from EMPs and GMDs and to prepare recommendations for a strategy to protect critical infrastructure. The act also directs Homeland Security to conduct R&D to mitigate EMP events, assess the possibility of a system to alert grid operators “within milliseconds” of a high-altitude nuclear explosion, and educate potentially affected infrastructure operators and emergency responders about EMP threats.

The Federal Energy Regulatory Commission has ordered electricity transmission system operators to take actions to mitigate the effect of E3 on high-voltage transformers and other equipment, commission acting chair Cheryl LaFleur said in the recent hearing. The industry has also taken steps to improve the resilience of the grid, including increasing the number of spare high-voltage transformers and other long-lead-time transmission components.

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