Microgrids on Islands

Slide 1
Microgrids on Islands:
The Unicorns have
Landed
There is much discussion of microgrids these days. Like the unicorn, everyone talks about them
but they are very hard to find. A recent conference addressed the twin topics of microgrids and
distributed power generation. An Island Inst. staffer attended and after many sessions on DG
he asked about Microgrids, and was told that there were actually no sessions on those. But as
islanders we have lived with microgrids for a long time, and we are pushing them towards a
greener future. Today we talk with people who are pushing the frontier.
Slide 2
This is Manhattan half blacked out by Hurricane Sandy. Just as generation is now spread
around through solar panels and wind turbines, people are thinking about how to give real
independence to parts of the grid as Microgrids. This puts the margins of society, where there
is no grid, on the map. Islanders already understand something about microgrids. No one
would build a microgrid if they could tie to the main grid, so only those on islands have had to.
Slide 3
Old island microgrids: no unicorns
When Mrco Polo traveled to the far east in the 13th C he encountered the Javan Rhinoceros and
wrote back: I have seen the unicorns and they are uglier than we thought. The classic diesel
island microgrid is a rhino not a unicorn.
Slide 4
Diesel generation
Pros
• Low cap investment
• Good load
• Noise
• Fumes
• Spills
• Load matching
Diesel generation
Pros:
-Low capital cost
-Load matching
Cons:
-Fumes
-Noise
-C2 Footprint
-Spills
-Fuel cost
Here is the ugly, noisy, polluting reality at the heart of the old island microgrid: a diesel
generating plant. The Park Service at Alcatraz discovered that they were on the list of the worst
offenders for point-source pollution in the state of CA and they did not want to be there, so they
have moved, as others have towards the true rare unicorn: the renewables microgrid. But the
virtues of the old systems we find are hard to match: they are relatively cheap, and they match
loads in ways that renewables cannot.
Slide 5
Island renewable
energy sources
But islands have lots of environmental energy: wind, sun, waves, tides. To move from diesel to
new renewale energy sources is to move away from the ugly old ugly rhino to the ideal of the
new unicorn.
Slide 6
Big diesel, Renewable Add-on
But how do you get there? You must deliver power every minute of every day, at a very high
standard to protect all the sensitive and sophisticaed devices that users attach to the microgrid.
A small first step can be adding a small amount of solar or wind energy on top of a constantly
running diesel generator. The diesel cannot turn off in case the sun goes behind a cloud. But
the diesel cannot turn down too far without becoming inefficient, producing pollution, and
ultimately damaging itself. So this is a strategy that cannot save much more than 20% of fuel in
general.
Slide 7
Big renewable, diesel backup
The other option: Renewable generation with a small diesel backup component, is the unicorn
that we want to move towards. But that means that storage must be added to the system so
that there is a source of power when the sun goes behind a cloud, or to carry loads all night.
Slide 8
Renewables don’t match demand
Because renewables are generated when the sun or wind are available, they do not match
loads. When the sun goes down is when you want to turn on the lights. So renewable systems
need power storage.
Slide 9
House to Village
A lot of little off grid houses have these things and work fine. But scaling from house to village
involves new engineering issues such as three-phase power, high voltages for transmission,
transformers, etc. Also, few have dared power a village in this way, so systems are not well
developed for this scale.
Slide 10
Renewable microgrid pros
• Ross Hanson: Operator of the Isle of Shoals
microgrid
• Charlie van Winkle: CEO of Northern
Reliability
Slide 11
We built one village system at the east end of the Elizabeth Islands and are now building a
second one at Cuttyhunk in the West. Our goal was to replace old diesel microgrids with sytems
dominated by renewable sources. We chose solar due to its overall match to our needs: more
power in summer, less in winter. We also liked its lack of moving parts, long life, silence, and
ease of siting. But we encountered the unicorn problem: technically and financially it looked
perfectly doable but we could not find a single village sized system to look at. Finally we
decided that the batteries were the hard part and selected a vendor favored by the firm that
makes the best battery. Alcatraz was the only system we could find where they were putting in
a big battery and turning off the generators, and they were far from done and having big
problems.
Slide 12
Here is the Naushon microgrid. It spans half a dozen close islands, has legs up to mile long, and
works at 480 volts using transformers to step up and down.
Slide 13
One hidden cost of diesel microgrids is oilspill cleanup. A special nightmare on an island with a
small drinking water aquifer, sensitive ocean waters surrounding, extremely high cost of
excavation and soil removal, etc.
Slide 14
We worked with Northern Reliability, who really understood lead/acid batteries, and here is the
battery system installed in the new electronics shed.
Slide 15
Here are the PV arrays. 512 panels with electronics shed at right.
Slide 16
August 2014
And this is the interplay between the generator, the PV and the load. The load is in purple and
is quite steady. The battery is in red, and is charged up each day and then drains each night. On
three of these nights the generator (In blue) came on in early morning to carry until sunrise.
Slide 17
Here is the Naushon control screen that shows the interplay of elements. As we approached
the Cuttyhunk job we thought about what we might do better in a second system. PV panels
and diesel generators have long lives, and are robust. Lead/acid batteries are well understood,
but fussy, expensive and unpredictable in lifespan. They are the wild card. And their HVAC and
charge controllers add headaches and complexity to the system. So we looked for other power
storage. A solid state system like this should just take the flip of a switch and then give a low
hum for years. There are no routine maintenance activities required at all by the system beyond
a monthly IR photo of the batteries. Yet we have swapped out the 30 charge controllers several
times.
Slide 18
Conservation
Generation
Here are the Naushon results: how much we generate from oil over nine years. Half cut by
conservation, half by renewable generation
Slide 19
Cuttyhunk Island:
Second chance
Now Cuttyhunk Island with 200 buildings is five times bigger than Naushon. What did we learn
at Naushon that we’ll do differently this time?
Slide 20
Screen shot from EOS site
Looking for the unicorn
The unicorn hunt: We reviewed who had built other renewables-based microgrids and how. We
found that everyone referred to us! I was pleased to see a microgrid button on the Eos battery
website.
Slide 21
But when I looked closely it was a strangely familiar image. The Naushon system was shown, in
which Eos played no part! Similarly a major solar contractor, when pressed for microgrid
experience referenced Naushon, but had had no role! Everyone wants to learn how to do this
hardly anyone has built one but the speakers today.
Slide 22
The way forward: New power storage
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Reduced capital cost
Long life
Non-toxic , non-polluting, quiet
Broad operating temp range
Partial charge/discharge okay
Low loss of stored power
Hi round-trip efficiency
Size and weight for installation
Low maintenance needs
Little service expertise
Addable, scalable
RELIABILITY is a requirement
Slide 23
Pump storage: air or water
Pump storage of water or air is low cost for those with good topography and easy
environmental regulators
Slide 24
Flow batteries have attractive qualities
Slide 25
Any storage system will be some sort of container-scale object, because portability is not a goal.
There are many new firms but it will be a while before we can be sure enough to use these
solutions. Perhaps by the time the Naushon system needs battery replacement.
Slide 26
We can foresee a day when the oceans will be full of unicorn islands