The overall objectives of the demonstration were to (1) install and evaluate an ORC system that produces electric power from waste heat using a heat source representative of commonly available low quality heat sources within DoD facilities, and (2) assess the applicability of ORC implementation across the DoD. These objectives were evaluated by the following activities.
Success factors validated during the demonstration include ORC energy production and integrated system efficiency gains, economics, and operability including reliability and availability.
The fully integrated packaged ORC/generator set system was deployed at the US Naval Station, Guantanamo Bay (GTMO) as determined by the DoD project partner in accordance with Southern’s site selection criteria.
The ORC engine converts waste heat into electric power and is able to use low quality (<250 ºC) heat through the use of organic working fluids with lower boiling points than the common steam-based cycle. Small scale ORC engines have recently become available which allow recovery of waste heat from comparatively small but omnipresent sources like internal combustion (IC) engines, gas fired boilers, turbines, waste oxidizers, process waste heat, solar thermal applications, and other sources.
Southern Research identified the ElectraTherm ORC generator as a well-designed and supported, cost effective, and appropriate ORC technology with a wide range of applications within DoD facilities.
ElectraTherm’s Power+ 6500 ORC generator is a compact, packaged system with gross output up to 110 kWe. The Power+ generator boasts simple installation, low maintenance, and integrated controls that allow the system to continue producing power from a variable waste heat supply without affecting the operation of upstream systems.
The Power+6500 utilized for this demonstration is a next generation model of ElectraTherm’s GM4000 model optimized to effectively utilize as much waste heat as thermodynamically practicable from a 1MW class diesel generator set, maximizing ORC power output. This class of generator set is commonly deployed to serve DoD installations and forward operating bases, utility peak load and industrial/commercial peak shaving applications, oil and gas exploration, and emergency standby generation.
To facilitate deployment, the integrated system was packaged in two standard 40 foot ISO shipping containers with design consideration given to safety, simple installation, and convenient operation. The integrated system consisted of the ORC generator and dry cooler (radiator) packaged in one container, and the diesel genset, switchgear and exhaust gas heat exchanger packaged in the second container.
The data collected and lessons learned from this demonstration provided ElectraTherm with the capability to adapt their product offerings to optimize power gain and efficiency from 1 MW class diesel generators and other applications with similar waste heat availability. This experience with packaged applications was of benefit to DoD, as well as ElectraTherm as it advances commercial availability of deployable systems.
Key demonstration objectives were achieved, including verification of overall system performance and economics, during baseline and intensive testing of the integrated system prior to deployment; however, some of the demonstration objectives, such as ORC internal efficiency, availability/reliability and operability could not be fully quantified due to lack of longer term, deployed testing caused by the failure to commission the genset on the GTMO grid following deployment. However, this issue was in no way caused by the ORC itself or by the integration of the ORC with the genset.
No implementation issues were encountered with the ElectraTherm ORC generator itself, ORC packaging, or with the integration of the ORC, radiator and genset. However, there were issues associated with the engine packaging and controls installation that caused significant project delays and ultimately resulted in failure to commission the integrated system on the GTMO grid leading to early termination of the demonstration before field measurements data could be collected.
Several issues such as subcontractor delays in getting the equipment installed, concerns with engine control wiring and programming delayed the system installation and integrated system operation and controls optimization.
The engine (CHP) and ORC containers were successfully finally installed at Guantanamo Bay Naval Station (GTMO) during the week of August 17-24, 2015. During initial testing, the ORC operated and performed as expected, however, the engine would trip (shut itself down) after several hours of operation in parallel with the GTMO grid.
Though the team was able to resolve these issues, unfortunately, before successful operation could be demonstrated, an arc flash event occurred within the generator housing, damaging the equipment. The arc flash was caused by improper location and mounting of a terminal block by CRM that, along with a poor wire termination, caused a signal wire to come loose and into contact with high voltage components. Although the damage appeared to be relatively minor, and may have been repairable on site, project budgets for all participants were stretched to the breaking point by this time. Given the difficulty and cost of conducting additional work at GTMO, and given reasonable concerns that further problems might be encountered, ESTCP made the decision to terminate the field deployment. Arrangements were then made to return the equipment to the States and transfer ownership to DoD.