Matthew Orosz Ph.D. Candidate Civil and Environmental Engineering (CEE) Massachusetts Institute of Technology President, Solar Turbine Group - 501(c)3 pending www.solarturbinegroup.org

MIT Parsons Laboratory 15 Vassar St. 48-216 Cambridge MA 02139 (508) 245-6199 [email protected]

Solar ORC PV-Thermal Generator demonstration at Eckerd College I Overview: In partnership with the Hemond and Ghoniem research groups at MIT, the Solar Turbine Group, and Sopogy Inc., we propose to install and test an experimental solar thermal power system at Eckerd College. The system will consist of a parabolic trough solar array occupying a footprint of 8 by 40 yards (less than 1/10th an acre) and an Organic Rankine Cycle (ORC) heat engine power block (~3 by 2 yards). The output of this system will be approximately 3kWe and up to 30kW of thermal energy in the form of hot water. This energy could be utilized by a facility at Eckerd if desired, or otherwise disposed of within the test apparatus. The purpose of this experiment is to demonstrate the concept of a combined solar thermal and PV system, and to serve as a U.S. based test bed for field trials of a similar unit in a clinic in Lesotho, in southern Africa. The system is designed to integrate with other sources of power typically available in offgrid situations, such as Diesel generators and PV panels, or to stand alone.

II System Specifications The parabolic trough solar array consists of modules supplied by Sopogy Inc. These have a slightly different aspect ratio than the troughs used in Lesotho (pictured in the diagrams) but are very similar. There will be a total of 20 units, in two rows of 10 each. A thermal fluid, ethylene glycol (car antifreeze), will be circulated in the absorber pipes at the focal line of the troughs, reaching a temperature of 300°F. This heat will be transferred to the ORC via a closed loop. One or more of the parabolic trough modules will also be equipped with photovoltaic devices at the absorbers for PV-thermal testing.

The ORC engine will be mounted in an enclosure, and will contain the heat exchanger for receiving the solar thermal energy, a heat exchanger for generating hot water, an expander-generator, fluid transfer pumps, control systems, batteries, and power electronics. Condenser coils from a Carrier HVAC unit will be mounted adjacent to the engine enclosure for heat rejection from the ORC. Additionally, a thermal storage tank will be mounted by the ORC. The ORC will be installed at one end of the parabolic array rows. III Site Requirements Orientation The rows of parabolas need to be accurately installed in a north south orientation (the 40yards stretching N-S), so that rotating around their axis will track the sun from east to west daily.

Mounting Each module has two support structures with 4-bolt flanges. These need to be bolted into matching flanges that are anchored securely, either to trusses in a roof if mounted on a flat building, or else into reinforced concrete footings. We can design and implement the anchorage or consult with/contract a local civil engineering contractor if the mounting requires compliance with local codes. Implementation We will cover all costs related to the installation and upkeep of the system, and will take responsibility for removing the system at the end of the project or at Eckerd’s request. Access to facilities and Project duration. 1. We require authorization for and access to the system site for the duration of the project, which would be a minimum of two years, or until either party decides to terminate the project. 2. While we do not require it, we would request access to a building or part of a building to use as a test load for the system. This would involve installing distribution lines and a manual transfer switch for switching between mains and solar power for electricity, and/or connecting to building plumbing for supplying hot water. 3. We would request access to roofed storage space (~1200ft2) for the flow of equipment and materials during site preparation, installation, and ongoing monitoring and evaluation of the system. 4. We would appreciate it if Eckerd could appoint a liaison to assume limited responsibility for the project when MIT team members are not on site. This

would include keeping an eye on the system, communicating with us if and when any issues arise, signing for the delivery of project-related equipment or materials and handling their storage, etc. 5. Access to a wired or wireless internet connection would be helpful for uploading data from the system’s data acquisition apparatus. 6. Access to a shop with basic tools would be helpful to assist with installation and maintenance tasks. 7. Any assistance with facilities for lodging team members during site visits would be appreciated. Outreach at Eckerd We are happy to discuss ways in which our project could integrate with the Eckerd community. This might include presentations in classes or seminars to spread awareness of the technical aspects of the system or the social objectives for deploying solar thermal in developing countries, involvement of faculty and students in hands-on aspects of the project’s installation or operation, or other research projects arising from the system operating on campus (economic analysis, avoided carbon emissions, sustainability, etc.). We could also produce informational media describing the project for people visiting Eckerd to help them learn about the system. Materials, Safety and Environmental Impact The Solar ORC system uses two working fluids in separate hermetic loops, monoethylene glycol (MEG) for heat transfer, and R-245fa (Pentaflouropropane) for the vapor cycle. MEG is car antifreeze; it is toxic if ingested (if spilled pets will sometimes imbibe it due to its sweet taste). Temperatures in the absorber can reach up to 400°F, at pressures of up to 40psi, and in the event of a loss of integrity exposure could lead to severe burns. The R-245fa working fluid in the ORC is a non-toxic and non-ozone depleting HFC. The R-245fa temperature can reach up to 275F at pressures of up to 300psi, and in the event of a loss of integrity exposure could lead to burns and injury. For these reasons is important to design and manage the system so that ruptures do not occur (the system is sealed and leak tested prior to loading the fluids), and to make sure that if containment fails the risk of exposure is minimized for anyone in the area. For both of these fluid loops, relief valves and expansion tanks are the safety measures in place to prevent over-pressurization. Warning signs are posted near the high temperature components. Anyone in the area should be made aware of the high temperature of pipes, and only trained personnel should have access to the ORC enclosure (we recommend a combination lock). Materials Safety Data Sheets for the working fluids will be posted in a clearly marked spot at the installation, and copies made available to Eckerd.

The solar array will displace and channel rainwater, and drainage might need to be considered. For ground mounting grading may be required to achieve a level field, and excavations are required for the concrete footings. The pumps, expander generator, and cooling fans in the power block will make some noise during the day, ~ 55db at 10ft. The fluids in the system must be properly reclaimed using specialized equipment at the end of the project lifetime, and the rest of the materials (mainly metals) can be recycled (we will take responsibility for this). About us: The Solar Turbine Group (www.solarturbinegroup.org) is a non-profit organization founded in 2006 by current graduate students and past graduates from MIT, with the objective of promoting solar thermal power in developing countries. Matt Orosz, Ph.D. candidate in Civil and Environmental Engineering, is a founder of STG and the lead graduate student on this project, which is funded under an MIT Energy Initiative grant with principal investigators Harold Hemond (CEE) and Ahmed Ghoniem (Mechanical Engineering). Previous funding for the STG mission in Lesotho has been provided by the World Bank through a Development Marketplace grant (2006).