Everybody talks about renewable intermittency, but nobody does anything about it.
Well, that is not quite true. Snohomish County Public Utility District is doing something about it: they are building the infrastructure for energy storage. Not balancing, but storage. There’s a big difference.
Snohomish PUD is the second largest publicly owned utility in Washington state and serves more than 327,000 electric customers.
A grid in balance
Right now, utilities “balance” their renewable inputs. Indeed, balancing renewables is a major focus of current utility research and practice. Most renewable sources are intermittent, and some other source of generation balances it—fills in the gaps. For example, when the wind springs up, hydro plants power down to balance. When the wind dies down, hydro plants power up.
In general, “balancing plants” have to be hydro or combined cycle gas-fired plants. Most “demand side management” is too slow to balance wind energy. Demand side management is when the utility manages the customer’s demand, not the power output of its generation plants. This technique requires cooperation with the utility’s customers, of course. However, while demand side management can solve some balancing problems, the speed at which wind energy can change output makes demand side management difficult. Few industries are willing to promise to power down and power up within ten minutes, whenever they are asked to do so. On the other hand, it is comparatively easy to arrange demand side management by asking industries to conserve energy between two p.m. and six p.m. on hot days.
In the Northwest, we have abundant hydro power, and hydro power is used for balancing. However, managing a river is more than just balancing the grid. The river must be also be managed in favor of the fish, for recreation, and sometimes for flood control. As a bottom line, most people would say that keeping the river in balance is very important, almost certainly more important than using the hydro plants to balance the wind output.
Storage, not balance. The MESA standards.
In other words, balancing the grid brings its own problems. But what if you didn’t have to use generation or demand side resources to balance the grid? What if you could store some of the energy when the wind is blowing, and use it when the wind dies down? If this could be achieved, intermittent renewables could become a much more important part of our electricity mix.
Snohomish PUD is a member of the Energy Northwest, and has an active program to help achieve cost effective, utility scale energy storage. Snohomish PUD is a founding member of MESA Standards Alliance (Modular Energy Storage Architecture)—other companies in the Pacific Northwest are also members. The MESA standards alliance is designing standards for the infrastructure of storage: at this point, storage (batteries, compressed air) simply does not scale to fit utility needs. There’s a disconnect between what the storage manufacturers are providing, and the kind of modularity and control that utilities need. The MESA standards are changing this by creating a standardized approach to the energy storage system controls and integration with utility SCADA and power scheduling software platforms.
To test the modular-storage-architecture concept, Snohomish PUD is first installing a one-megawatt storage facility (lithium batteries) with all necessary controls. This system is almost ready for implementation, which is planned for this quarter (fourth quarter 2014). This project will be expanded in 2015 with an additional megawatt of capacity. The staff at Snohomish PUD, along with subcontractor 1Energy, are leading this effort with a team that includes the following groups:
Substation Engineering / Construction; Communications, SCADA, and IT; System Planning and Protection; Environmental and Safety; Power Scheduling; Facilities; and, Cyber Security.
The Pacific Northwest Leads Again
The Snohomish PUD storage initiative is another way that the Pacific Northwest continues to lead in the quest for reliable, clean, inexpensive energy!
(Written by Meredith Angwin)