Predicting how rumours and epidemics percolate through
populations, or how traffic jams spread through city streets, are
network analyst Jian-Wei Wang's bread and butter. But his latest
findings are likely to spark worries in the US: he's worked out how
attackers could cause a cascade of network failures in the US's
west-coast electricity grid - cutting power to economic powerhouses
Silicon Valley and Hollywood.
Wang and colleagues at Dalian University of Technology in the
Chinese province of Liaoning modelled the US's west-coast grid
using publicly available data on how it, and its subnetworks, are
connected (Safety Science, DOI: 10.1016/j.ssci.2009.02.002).
Their aim was to examine the potential for cascade failures,
where a major power outage in a subnetwork results in power being
dumped into an adjacent subnetwork, causing a chain reaction of
failures. Where, they wondered, were the weak spots? Common sense
suggests they should be the most highly loaded networks, since
pulling them offline would dump more energy into smaller
networks.
To find out if this is indeed the case, the team analysed both
the power loading and the number of connections of each grid
subnetwork to establish the order in which they would trip out in
the event of a major failure. To their surprise, under particular
loading conditions, taking out a lightly loaded subnetwork first
caused more of the grid to trip out than starting with a highly
loaded one.
"An attack on the nodes with the lowest loads can be a more
effective way to destroy the electrical power grid of the western
US due to cascading failures," Wang says. To minimise the risk, he
says, the grid's operators should defend the west coast sections by
adjusting their power capacity to ensure these specific conditions
do not arise.
The US Department of Homeland Security is reviewing the
research, says John Verrico, the department's technology spokesman,
who adds that countermeasures are already in the works. "Our
engineers are working on a self-limiting, high-temperature
superconductor technology which would stop and prevent power surges
generated anywhere in the system from spreading to other
substations. Pilot tests in New York City may be ready as soon as
2010."
These precautions are well and good, but there are easier ways
to bring a grid down, says Ian Fells, an expert in energy
conversion at Newcastle University, UK. "A determined attacker
would not fool around with the electricity inputs or whatever -
they need only a bunch of guys with some Semtex to blow up the grid
lines near a power station."