Concentration and Storage of Solar Energy in Mining Facilities

Our project is to develop a testing bed that will help determine the feasibility of storing solar energy within a mining facility. Mining operations leave behind a plethora of usable materials such as waste rocks, Carbon Dioxide and a large amounts of usable land. We wish to take these leftover materials and put them to use storing solar energy.

=Problem Definition= Mining facilities in the United States have several drawbacks. They are major sources of pollution, they destroy the environment where the mining takes place and when mining is completed the facility is left as an open pit and the workers lose their jobs. We wish to take these negatives and turn them into profitable solutions.

Background
The idea to turn mining negatives into solutions came from Ray Donelick. He approached the University of Idaho seeking assistance in designing a small scale solution. Ray envisioned a system to focus solar energy and store the heat generated inside of a back-filled mining pit. Solar collectors will focus the energy on a receiver carrying Water. The water will then pass through a heat exchanger depositing the energy into Carbon Dioxide, one of the major pollutants from fossil fuel energy generation. the hot carbon dioxide will then run underground to the thermal storage container. This container consists of a insulating outer barrier with mining waste gravel on the inside. The carbon dioxide will run into the thermal storage container and deposit the heat into the mining waste gravel where it can be stored for long periods of time. Once the energy is stored, the consumer can tap into the available energy when solar energy cannot be readily collected.

Deliverables
The deliverables for this project is a complete testing bed to provide a proof of concept. The parts that will make up this testing bed are as follows:
 * One solar collection system. This will either be a parabolic trough or linear fresnel system.
 * Two heat exchangers. One between the solar collection system and the thermal storage system and one between the thermal storage system and the consumer outlet lines.
 * Two in-line filters, one upstream of each heat exchanger.
 * Two pumps. One liquid pump to move the water through the solar collection system and one gas pump to move carbon dioxide through the thermal storage system.
 * Globe valves throughout the system wherever appropriate.
 * The thermal collection system. This will be constructed by Ray Donelick in close cooperation with our design.
 * Temperature and pressure sensors at each point of interest in the system. 5 of each sensor total.

Specifications
The specific specifications of the system are still being determined. We expect the system to have a total thermal efficiency greater than 60%. We also expect the thermal storage system to be able to supply the consumer with at least 150 degrees Fahrenheit of usable energy.

=Design Considerations= There are several large considerations we have had to deal with. The biggest considerations are as follows:
 * Solar collection systems are typically very large (10X20 meters or more). We do not currently have the space or capabilities to house a system like this.
 * The solar collection system cannot require special equipment or a concrete foundation for construction.
 * We only have access to 110 volt power supplies. Any pumps we acquire will have to run on standard household appliance circuits.
 * Any working fluids we use cannot freeze in sub-zero temperatures.
 * Piping materials and sealants must be commercially available at most department stores.
 * Piping materials and sealants must be able to withstand the temperatures of the working fluids within them.
 * Temperature and pressure probes will have to be accurate within the appropriate temperature ranges.
 * The data collection system will have to store data for long periods of time, preferably within a CSV file or any other readily usable file format.

=Project Learning= Our main purpose for this project was to concentrate solar energy and store it in a test system. However due to cost issues we were not able to acquire a solar collector. The scope of our project then changed to the design of the testing bed and building a scale model. The following sections will describe the learning associated with each part of the project.

Solar Collection System
The largest component of our project was a solar concentrating device. This would focus sunlight into a single line where it could heat the working fluid. These devices are readily available and come in several different configurations. Solar troughs use a parabolic trough to focus the sunlight to the central point. These tend to be the most efficient but are the most expensive and most susceptible to weather. Linear Fresnel Mirrors act like a parabolic trough, but use an array of flat mirrors to imitate the parabolic curve. This creates less weather susceptibility at the price of efficiency. Both of these ideas were considered and two major problems arose. One, the size of these devices varies, but is no smaller than 70 squared feet. This is larger than we had room to house. Another issue was the cost. A single system at 70 square feet came with a price of $10,000 which was well outside of our budget. For more information on these systems, click the links under the pictures below.

=Final Design=

=Validation=

=Team Members=

=Additional Documentation=

Project Schedule

[[Media:project schedule.pdf|Project Schedule]]

Meeting Minutes

[[Media:Meeting Minutes 9-10.pdf|Meeting Minutes September 10th]] [[Media:Meeting Minutes 9-17.pdf|Meeting Minutes September 17th]] [[Media:Meeting Minutes 9-24.pdf|Meeting Minutes September 24th]] [[Media:Meeting minutes 10-9.pdf|Meeting Minutes October 9th]] [[Media:Meeting Minutes 10-16.pdf|Meeting Minutes October 16th]] [[Media:Meeting Minutes 10-23.pdf|Meeting Minutes October 23th]] [[Media:Meeting Minutes 10-30.pdf|Meeting Minutes October 30th]]

Presentations

[[Media:Meeting 10-02.pdf | Solar Collection Methods]] [[Media:Thermal Analysis .pdf | Early System Analysis]] [[Media:design review meeting.pdf | Design Review Presentation]]

Snapshot Posters

[[Media:snapshot 1 poster.pdf | First Snapshot Posterboard]] [[Media:snapshot 2 poster.pdf | Second Snapshot Posterboard]]

Reference Materials

[[Media:Re technologies cost analysis-csp.pdf|Cost analysis of Renewable Energy Technologies]] [[Media:Solar trough mathmatical report.pdf|Heat Transfer Analysis and Modeling of a Parabolic Trough Solar Receiver Implemented in Engineering Equation Solver]] [[Media:Thermal analysys of the performance of linear fresnel collectors.pdf|Thermal Analysis of the Performance of Linear Fresnel Solar Concentrator]] [[Media:Thermal efficiencies of linear fresnel collectors with other working fluids.pdf|Methodology for the Thermal Characterization of Linear Fresnel Collectors: Comparative of Different Configurations and Working Fluids]] [[Media:1-s2.0-S1365160902000229-main.pdf|A modeling approach for analysis of coupled multiphase fluid flow, heat transfer, and deformation in fractured porous rock]]