…Microgrids: All that Glitters is not Gold…
Organizations and people who are promoting a product or idea, frequently overstate and embellish the benefits of what they are promoting.
There are many examples of this, from the snake-oil salesman of yesteryear to today’s promoter of microgrids.
A related recent example is the advertisement by proponents of wind energy posted around London claiming that wind energy is 50% less expensive. The advertisement campaign had to be curtailed because the claim was false.
Recent disasters are fertile ground for claims about microgrids.
There was hurricane Maria in Puerto Rico, after which promotors of microgrids hyped them for replacing the damaged grid. See Understanding Microgrids.
More recently, there was the fire at Hartsfield-Jackson Airport in Atlanta, where microgrids are being touted to replace the existing distribution system.
Proponents of microgrids are:
“Asking Georgia Power whether it had considered investigating the installation of functional microgrids, one that derived power from renewable energy resources, at [the] Atlanta airport.”
Notice the emphasis on renewable power, in this case from solar. Microgrids are nearly always a front for promoting wind or solar generation.
Microgrids are being used to foster the development of wind and solar while claiming that they provide improved reliability or resiliency.
As in Puerto Rico, microgrids would not have improved reliability or resiliency since it was the transmission and distribution system, not the power plants, that caused the extensive outages. As above, see Understanding Microgrids.
Hartsfield was in many respects similar to the situation in Puerto Rico, in that it was a section of the distribution system that was destroyed in a fire. The fire was in a tunnel which also housed the backup system. Housing both together could be considered a bad design, but microgrids would not have helped.
In fact, there are many traditional practices that could be used at a modest cost to resolve the issue, while microgrids, with unneeded solar generation, would be extremely expensive.
Housing redundant systems in a separate tunnel would be one solution, assuming space was available for another tunnel.
Another relatively inexpensive solution would be a loop feed, which is commonly used by the utility industry, where distribution cables are looped in a circle around all the places being served by the feed.
For example, loop feeds are nearly always used for underground distribution in housing developments. A loop feed can be viewed as a circular feed with a switch at the center of the loop that is normally kept open, where the electricity is delivered from either direction to all the houses being served by the loop.
If there is a fault at one section of the loop, the damaged portion can be isolated by opening switches (installed in each distribution transformer) at both ends of the damaged section. With the fault isolated, power can be restored to the rest of the homes on the loop.
Such a loop feed could be installed at the airport, or anywhere else where redundancy or resiliency is important.
Microgrids are not necessary for improving reliability or resiliency, as there are established practices, such as loop feeds, that are far less costly and that will probably work better.
Beware the hype supporting microgrids. In nearly all instances, benefits are exaggerated while their higher costs are ignored.
Microgrids are almost always far more costly than established practices.
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