One very generous donation. Many possibilities.
Thanks to one Cornell alum, many forward-thinking island engineers and mentors, and the Sustainable Engineering Interns (SEI), Appledore island just got “greener.” Here is the story behind the new microgrid at Shoals Marine Laboratory (SML) and how it is helping the island become more sustainable.
Some Background Please
SML relies upon a combination two green grids, three diesel generators, and a wind turbine to supply the island with around-the-clock electrical power. Of course, our mission is to be as sustainable as possible, so we strive to reduce our dependence on diesel fuel and increase our reliance upon clean, renewable energy.
The main green energy grid on the island works by harnessing energy from the wind via the Bergey Wind Turbine and from the sun via photovoltaic panels (solar panels). This energy is then stored in Absorbent Glass Mat (AGM) batteries, more commonly referred to as lead-acid batteries, which are the same kind you use in your car. The main battery bank for the green grid is housed in the Energy Conservation Building.
With 331 solar panels at Shoals, our limitation lies not in the generation of enough green power (we have a lot of excess, actually), but rather in the storage of this energy.
So, why don't we get more batteries? The short answer is that batteries expensive and SML is all about innovation – finding both more sustainable and more cost-effective solutions to power Appledore Island.
That’s why this summer's SEI’s have been working on projects that dive into these technical challenges, focusing on factors like depth of discharge (DOD), which looks at how far a battery can be drawn down without compromising battery life... basically, getting the most out of your batteries!
However, the main project our SEI's are tackling focuses on removing the most energy intensive piece of equipment – the saltwater pump – from the main green grid and isolating it on its own microgrid, which would not have been possible if not from a little help from generous supporter, Sean O'Day.
From the Army to Appledore
In the Spring of 2017, Shoals Marine Laboratory (SML) received a huge donation from Cornell alum, Sean O'Day. The donation? A Mobile Renewable Energy Unit (MREU) designed by Florida Solar Energy.
The MREU is a compact, mobile energy generation and storage system, that was originally designed to be integrated into existing utility grids in permanent military outposts. A video illustrating the setup of the unit is shown below.
The hope was that the MREU could be used on Appledore to increase the island's energy efficiency and reduce the overall load on the green grid by creating a microgrid. So, the 2017 SEI's were tasked with assessing the cost-benefit analysis of transporting this unit to Appledore Island, as well as what part of the island’s electrical load it might be able to handle to provide relief to our main green grid.
The 2017 SEI's found that it would be beneficial to have the MREU since it would greatly reduce dependency on the island's diesel generator. Thus, they recommended using the MREU as a microgrid that would eventually support the island's energy-intensive saltwater pump, which runs continuously (all day and all night) to support the marine lab’s touch tanks and laboratories.
Since last summer, the MREU has been reconfigured to create the new microgrid. The current challenge? The system only works on a manual system (someone must manually switch between the microgrid and main grid when energy runs low). Ideally, this system should automatically switch over to the main grid if power is low. Because of this issue, the island’s green energy infrastructure has not yet been able to power the island all night. No one has yet monitored the system overnight to see if it (on an ideal solar day) can fully support the saltwater pump through the night... until now!
This summer, two of the 2018 SEI's, Tak and Gabby, are spending a night in Kingsbury House (also known as K House) to monitor the MREU through the night for the first time! The hope? That the MREU will support the constant load from the saltwater pump throughout the night and not get down to 30% DOD (draw the batteries down too much) to the point that it would need to switch-over to the diesel generators and begin taxing that system.
This will mark a pivotal moment in SML history if the green energy systems – the main green grid and the new MREU microgrid – can support the island’s entire electrical load through the day and night (after an ideal solar day), with no reliance on diesel generators!
It’s the SEI’s that continually seek to improve the facilities and processes at SML to make them more efficient and ultimately, more sustainable. After their summer on Appledore Island, they leave recommendations for future projects and data to continue existing ones, such as the MREU system. It is their efforts and green energy solutions that have helped Shoals reduce diesel fuel consumption by over 80% since 2006.
Stay tuned for the results of the all-nighter in K House and for what Gabby and Tak uncover with the new MREU microgrid system!