After the onslaught of Hurricane Sandy, the eastern seaboard just experienced the biggest blackout since 2003 (when a large-scale power line failure in Ohio caused several states and millions of customers to lose electricity). According to a statement issued today by New York power supplier Con Edison, “Hurricane Sandy toppled trees and flooded underground equipment in the most devastating storm in company history.”
The company approximated that 780,000 customers were without power as of this morning and estimated, “that customers in Brooklyn and Manhattan served by underground electric equipment should have power back within four days. Restoration to all customers in other areas served by overhead power lines will take at least a week.”
In the face of such huge outages and long repair estimates we at PolicyMic we were curious: Just how does the power grid work? Why was power shut off to lower Manhattan even prior to the storm’s arrival, and, why is it taking so freaking long to get it back on? To find out, we chatted with an energy consultant. Here’s what we learned.
There are pre-existing problems with the grid:
In the U.S. we use the AC system (alternating current) versus the DC system. Unfortunately, like picking the Imperial over the Metric system, we chose the wrong one. A direct current can shoot power out to one spot. But, with an alternating current you need an equal and opposite transition to balance the system, otherwise the system fails. Basically, we already have an AC grid system much more vulnerable to voltage crash, because there are more points of weakness, a.k.a. more opportunities for Sandy to do damage.
Another problem with New York is that we have one of oldest grid systems in country, with a framework built in the 1920s. New York used to have multiple utility companies, but they were consolidated when the state created a privately owned monopoly in the ’20s. This has evolved to the point where ConEd is basically the single energy provider for New York City along with a few others servicing the rest of the state.
This led to the last complication — the current way energy is sold. In our system today, power plants, the actual electrical generators, are called upon to ramp up and down their power output as the grid operator (companies like ConEd) requests. Usually an hour ahead, the operator requests X much electricity in market for the next hour. Power is bought from the generators in an auction format until the price goes up for supply to equal demand (marginal price).
The energy business is based solely on how much energy the distributor needs in a given hour, and as little incremental investment as they can do to keep the lights on. With the way the market currently works, there’s no incentive to build new infrastructure, especially considering that cost recovery for building said infrastructure takes up to 40 years, distributed as confusing riders on your electric bill.
How the power grid actually works:
To picture the electrical system, imagine a very broad set of tubes channeling water around to various spots. In certain spots, if small parts of the tubes get damaged or fall away, the tubes can keep functioning. But, if a particular spot goes out or the number of holes reaches a critical point, the water (electrons) will stop flowing. The water falls out of the system. For the electric grid to run, it needs to maintain a certain level of voltage. If that voltage collapses below a certain point, the system breaks. Additionally, at various points, there are gates that control the flow of the energy. If any of the gates are damaged, this is also a problem.
To get to your home, electricity is first created in a generator, which is a power plant. From the generator, a transformer — the big boxes you see — steps up or down the amount of megawatts delivered to customers. If a large transformer, on a high voltage, or “backbone” line is damaged it can cause widespread blackouts, like in 2003. The transformer regulates the amount of power that goes to operate local lines (like the ones birds sit on outside your apartment).
How the grid broke and why it will take so long to fix:
For above ground lines, utility crews can’t go up in crane boxes to repair them until the wind dies down. Until the wind calms down, repairs can't even start. Some of you may have also seen the viral video or heard news of the ConEd transformer that exploded in lower Manhattan. Without this transformer — one of the water gates — the company has lost its connection between the power plant and the local lines.
In its statement today ConEd also reported that flooding is also preventing swift repairs, “Restoring electrical service to underground equipment demands cleaning all components of sea water, drying and testing to make it safe to restore power.”
If turning power back on could lead to larger blackout, they’ll wait until diagnostics are done before turning it back on.
Water damage was also the reason for the preemptive shut down to the downtown area. According to Bloomberg Business News, “blackouts in Manhattan, which covered much of the city below 39th Street, were caused by flooding in substations as the storm surge brought water into Battery Park, the East Village and Chelsea. Con Edison killed power in those areas last night to limit damage from salt water reaching its equipment.”
The company is also turning on the power in stages, according to need, as you can see from this map. They’ll first focus on the most populous areas and go from there. Hospitals and nursing homes are also given priority. Power will take longer to reach the suburbs because the company will first restore the lines that serve the most people.
Mostly however, if repair personnel need to put new transformers in, and repair hundreds of lines, that will take time. Let’s remember that this is the most extensive damage to the power grid ever and try to sit tight.