Microgrids: the means for grid secession or a utility's best friend?
Tea partiers take note: the technological means to secede from the union, er, the grid is nearly here.
That is, unless the electric utilities beat you to it and use your institution or community as a means to shed load for demand response. (You wanted off-grid, you got it!) Rather than shutting off power to a large swath of residences and businesses to avoid an overwhelming load, taking a handful of microgrids offline would not affect service within those microgrids, which are prepared to act as "islands." Talk about a smart grid.
Or, utilities may want to create microgrids from service areas which can be encouraged to develop high penetration of renewable resources - perhaps owned by the utility and leased to commercial building landlords - as a means for the utility to achieve its renewable portfolio standard (RPS) through distributed generation.
"Everyone is so far behind their renewable portfolio standard goals, at least in California where siting utility-scale renewables is difficult, that this actually makes sense," according to analyst Peter Asmus of Pike Research, who has authored a new report on the topic.
This potential push-me-pull-you game may not develop, of course, if a more cooperative and likelier scenario materializes.
"Most microgrids will be grid-tied," Asmus said. "They'll be able to draw power from or shift power to the main grid."
But if that macro-grid goes down, your institution or community can continue to function under its own power, which provides a powerful allure for many entities that may find microgrids an attractive proposition. Those entities include the military, hospitals or campuses, which see the promise of reliability and security in microgrids.
May as well draw a breath here and give Asmus' definition of "microgrid," which, he told me, suffers a bit from a range of evolving definitions.
"I think of the microgrid as an integrated energy system, with distributed energy resources and multiple loads that can perform autonomously in parallel with, or islanded from, the main grid," Asmus said.
And that brings up a popular misconception about microgrids, according to Asmus.
Although microgrids typically are discussed in terms of their ability to manage and buffer high penetration of renewable resources and serve certain smart grid reliability functions, they are not wholly green animals. Fossil-fuel driven generators are a major reliability component of many microgrids, particularly those that serve institutions such as the military or corporate headquarters or a hospital, which essentially have to mimic the macro-grid by producing reliable, constant baseload generation.
One of the most powerful drivers for microgrid adoption has been the development of inverters that link the microgrid "island" with the main grid and keep the "island" working when the macrogrid goes down. (According to Asmus, the new, microgrid-enabling inverters are in the pre-commercial stage right now.)
The typical inverter that, for example, converts solar photovoltaic panel output in DC current to AC current for use by a home or business, shuts down the PV system when it senses that the macrogrid has gone down. This was required by code and by the utilities so that no distributed generation could surprise and deliver a shock to a utility worker working to restore power on the grid. In contrast, the new generation of microgrid inverters will keep the "island" powered while disconnecting from the macrogrid, Asmus explained.
"There's also a cultural component," Asmus said. "The utilities have been testing the technology to answer their main concern: 'can we trust these new inverters?'"
The answer appears to be yes, as several major utilities have put the new inverters to the test and the Institute of Electrical and Electronics Engineers (IEEE) appears to be working on developing protocols for safe islanding, according to the analyst. In the future, we'll look at early adopters, which reportedly include electric utilities and their headquarters.
As for momentum, Asmus has forecast that over three gigawatts of new microgrid capacity will come on line in the next five years, representing a cumulative investment of $7.8 billion. North America will be the largest market, capturing about three-quarters of the projected capacity. In North America, Asmus projects that institutional microgrids will lead. In Europe and the Asia Pacific region, community microgrids will lead.
Accrording to Asmus, other developments will help drive this emerging trend. Greener, cheaper storage within the microgrid for emergency backup and as a buffer for intermittent renewable energy generation will push adoption rates. And as the price of renewable resource generation continues to fall, microgrids will be able to produce more distributed energy, sustaining themselves.
We'll soon look to pilots and demos in this area for further exploration of the topic. Any suggestions, dear reader?
Phil Carson
Editor-in-chief
Intelligent Utility Daily
pcarson@energycentral.com
303-228-4757
Comments
Microgrids emerging rapidly
Thanks for this excellent overview and update. The common misconception that microgrids are all about islanding or about divorcing from the grid is starting to fade. We (Pareto Energy) were part of a workshop yesterday at the US Energy Association on this very topic (a webcast should be available soon):
http://www.usea.org/USEA_Now/USEA_Now.htm
Microgrids can be a utility-friendly (or even utility-owned) approach for concentrating certain kinds of energy services: reliability, power quality, high penetration levels of renewables and DG, etc. They're also ideal for increasing the efficiency of any thermal generation, whether natural gas or zero carbon, because they're small and local, so you can capture and use all that waste heat that goes up the stack at central plants.
We're seeing rapidly increasing interest -- and finally adoption -- of microgrids for downtowns, hospital districts, campus settings, airports, and government complexes, and other high-density and/or high-reliability settings. As utilities get more comfortable with the inverter-based interconnection approaches (such as Pareto's GridLink), and with some new regulatory / ownership models that protect their financial interests, we believe the adoption rate will increase even more.
--Shalom Flank, Ph.D.
CTO & Microgrid Architect
Pareto Energy LTD
Microgrids
It's an intriguing idea but I don't see a compelling value proposition other than an ability to completely disconnect from the "macro" grid. Something similar could be accomplished by making some minor modifications at the substation level so that the customers served by that substation can be islanded when and if necessary.
From a supply reliability standpoint, micro grids only have an advantage to the extent they offer a larger reserve margin than the macro grid, but that's expensive. For DG with surplus, a micro grid offers fewer potential buyers and potentially lower prices. For buyers, microgrids may create an illusion of enhanced reliability thatmay not exist.
One of the challenges of electricity markets generally is that they tend to be fragmented by transmission constraints, which makes them small and illiquid. Microgrids do nothing to expand the size of these markets.