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Rethinking Geothermal

Rygan Corporation’s ground-heat exchange system helps heat and cool a historic US landmark

In 2010, the multinational consultancy and engineering company Amec Foster Wheeler faced a critical design challenge with one of its American clients, the National Park Service (NPS).The NPS is an agency of the US government that manages all of the country’s national parks, national monuments and other
conservation and historical properties.
One of its most recognised historical venues, the Longfellow House in Cambridge, Massachusetts, was suffering from a failed geothermal system and costing the agency exorbitant amounts to operate auxiliary heating and cooling systems.

GEO SYSTEMS

There was much at stake for both the NPS and Amec. The venue is an all-wood structure of mid- Georgian architecture, which houses priceless historical documents and artefacts, all of which depend on precise, dependable humidity- and climate-control systems for preservation. The original geothermal system designed to provide and sustain these critical functions was an open or ‘pump and dump’ type system. Because open systems circulate groundwater directly through the heat pump, they can be very efficient, allowing direct access to the groundwater’s thermal energy. Unfortunately for the Longfellow house, however, its groundwater contained high concentrations of iron and manganese that fouled the pumps and pipes feeding the system – a common problem for open systems in that area. The open style was originally selected because there wasn’t enough available space on the grounds to install a closed-loop, U-bend system. Closed systems are made of polyethylene plastic, which is impervious to harsh groundwater, but require more wellbores and land space to compensate for the material’s poor heat transfer characteristics. For a geo system to feasibly exist on this site, the Amec consultants needed a new technology.

NEW DESIGN

Senior Amec project manager and engineer John Peterson led the design and geo implementation for the Longfellow site. He had learned of a new composite-based closed-loop system, which had only been commercially available for a few years. Rygan Corporation, a material sciences company from Tulsa, Oklahoma, had developed a low thermal resistance fibreglass composite system that had been successfully used on other projects. After representatives from the two companies met, Amec decided to conduct a test utilising the new composite system in one of the existing open wellbores. The performance Peterson witnessed from the test bore resulted in a new design for the Longfellow house based entirely on the Rygan composite system. According to Peterson, the Rygan technology provided the NPS with a sustainable, geo-based solution, which would have otherwise been impossible due to land space constraints and archaeological restrictions. “The site grounds presented numerous rygan-pipeconstraints and archaeological barriers to drilling or land disruption. A traditional polyethylene U-bend type system would have required drilling and trenching for 20 wellbores, which was impossible for the site. The Rygan system allowed us to provide a high-performing yet closed system, impervious to groundwater elements and with minimal drilling and disruption,” he said. Peterson also stated that the performance they’ve seen on the Longfellow house “isn’t achievable with traditional systems, open or closed”, and that the system has enabled solutions they couldn’t have conceived of seven years ago.

URBAN PROJECTS

Since the commissioning of the Longfellow house in 2011, the use of Rygan-based geo systems has grown with government, commercial and residential jobs across the US, often in areas that could not accommodate another geothermal system due to space restrictions. “Most of our projects happen in urban and metropolitan settings, says Rygan co-founder and chief operating officer Lane Lawless. “Our material with its coaxial configuration greatly reduces thermal resistance between the formation and the heat pumps on the surface. Because we’re more efficiently and effectively exchanging heat with the ground, we usually need half or less of the drilling and land space required for traditional polyethylene U-bend systems. This ultimately means we can deliver geo-based solutions to the more densely populated urban areas that have traditionally been ineligible for geo due to space constrictions.” When asked if Rygan has plans to move beyond North America, Lawless says the framework for that is now in the works. “We have several potential projects we’re looking at in the UK and Scandinavia. The key is having a good indigenous partner who will exert quality control over design and installation. We’ve been fortunate to work with superb designers and installers in the US, and now we believe we’ve found that same quality of partner in the UK. Regardless of your technology, it takes quality minded people to deliver a quality geo solution.”

RYGAN UK

Rygan Energy Solutions has been selected as the approved partner for the UK market. It will deliver the Rygan technology as a turnkey, mechanical solution, with a full design and installation service. “We have our first commercial installation in the UK in March this year,” says Lee Hormell, director of Rygan Energy Solutions and Waterseekers Well Drilling UK Ltd, “and have several projects in the pipeline. Due to the success of Rygan-based systems in the US, a repeatable template has already been established that we can utilise here.”

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