Transmission month: two more ideas to quickly boost the transmission grid
Greetings, faithful Volts readers! Welcome back to the Transmission Week that never ends.
The news these last few days has been filled with talk about electricity grids. Texas is suffering from an unprecedented cold snap that has left more than four million people without power for days. It’s a terrible situation. There’s a lot to say about it, what can and can’t be learned, and perhaps I’ll get to it next week.
But you didn’t sign up for a breaking-news email, you signed up for Volts! So today brings what I believe what I believe will be my last big transmission post, though I may do a wrap-up after this. Thank you for traveling with me on this longer-than-expected journey.
Today, we’re going to look at a couple of final ideas to make the transmission grid work better, short of building new lines — a remainder bin of grid-enhancing technologies, if you will.
Idea #1: Using energy storage as a transmission asset
At least since the Energy Policy Act of 2005, the US government has acknowledged that energy storage technologies can be used to ease grid congestion and increase the reliability and flexibility of energy transmission. In recent years, there has been increasing interest in “storage as a transmission asset” (SATA), which refers to energy storage installations that are treated as transmission assets — meaning utilities can “rate base” them and receive a guaranteed rate of return plus any tariffs or incentives for transmission assets.
Basically, it means allowing some storage to be treated — legally, financially, and operationally — like a piece of the transmission system.
SATA projects — sometimes known as “virtual power lines” — offer a range of benefits to regional energy grids.
When a line is congested, it can offload some power to storage. At times of lower congestion, stored power can be injected to maintain high line utilization. Storage can thus relieve congestion and make the grid more reliable. It is much cheaper and quicker to deploy than new transmission, its footprint is much smaller, and it faces a much less onerous regulatory process. It is extremely modular and scalable, which means it can start small and be scaled up precisely to need, and even relocated as grid needs change.
Congestion on a power line often causes “inefficient dispatch,” meaning grid operators must ask generators on one side of the line to curtail their output and generators on the other side of the line to ramp theirs up, even if that isn’t the most cost-effective option. Storage on either side of the line can help reduce inefficient dispatch.
Another key service storage can provide is to free up unused line capacity. A grid capacity standard called “N-1” holds that the grid must maintain safe operation if a “contingency event” takes out one of the lines. This means all lines must maintain some reserve capacity to absorb energy in the event of an N-1 situation.
But storage can serve that purpose — rapidly injecting energy into, or absorbing energy from, the grid in the case of a contingency event — even better than power lines. Adding SATA projects can free up some of that reserve line capacity to carry more power.
As with most things transmission, Europe is way ahead of the US on this. Most notably, Germany is developing 1,300 MW worth of SATA in a project known as Netzbooster (grid booste
