Concentration and Storage of Solar Energy in Mining Facilities
|Our Team Logo|
|Team Name||Solar Rocks|
|Duration||Fall 2018 - Spring 2019|
|Faculty Adviser||Behnaz Rezaie, Ph.D., P.E.|
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.
- 1 Problem Definition
- 2 Specifications
- 3 Design Considerations
- 4 Project Learning
- 5 Final Design
- 6 Validation
- 7 Team Members
- 8 Additional Documentation
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.
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.
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 in-line air heater. This will heat take the place of a solar collector for testing purposes.
- One pump. One gas pump to move air through the thermal storage system.
- Three globe valves. These will allow us to store or release air from the system.
- The thermal collection system. This will be where the mining waste rock is stored and heated.
- Temperature and pressure sensors at each point of interest in the system. three temperature sensors and two pressure sensors.
The specific specifications of the system are still being determined. As this is a testing bed, we want to be able to apply a wide range of values for fluid temperature, pressure, and flow rates. We also wish to construct the system as close to real-life conditions as possible. Below are some general requirements of the system.
The thermal chamber must be able to perform under the following conditions:
- Being buried under 40 feet of dirt.
- Withstand temperatures of up to 600 Fahrenheit.
- Withstand pressures of up to 2 atmospheres.
- Not allow the working fluid to leak from the system.
The in-line heater must be able to perform under the following conditions:
- Heat the working fluid within a range of 200-600 Fahrenheit.
- Operate at pressures up to 2 atmospheres.
- Operate at a variety of fluid flow rates.
The air blower must be able to perform under the following conditions:
- Operate at fluid temperatures of up to 600 Fahrenheit.
- Supply a variety of fluid flow rates.
- Operate at pressures up to 2 atmospheres.
There are several large considerations we have had to deal with. The biggest considerations are as follows:
- We only have access to 240 volt power supplies. Any pump or heater 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.
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. I have attached the latest system diagram below. The testing bed requires a thermal chamber, an in-line heater, an air blower, an air compressor, and several globe valves. 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. For more information on concentrated solar power in general click here.
Since a solar collection system was impossible, we decided to focus more on the thermal chamber aspect of the project. Our current restrictions are mainly size orientated. We have been allotted a space of about 15X15X10.5 feet to house the chamber and all components. We are aiming for a chamber size of around 8X8X8 feet.
A in-line heater will take the place of the solar collection system for our testing. We need a heater that can heat air to 600 Fahrenheit and handle multiple flow rates. Currently we have found an in-line heater we wish to investigate more. The heater can heat air up to 600 Fahrenheit, runs off of a 240 volt power supply, and can supply a maximum 2000 Watts of energy to the system. For more detail about this specific heater, click here.
Currently, we have not done much research into this device. See the air blower section of the specifications tab for the applicable requirements.
Meeting Minutes September 10th
Cost analysis of Renewable Energy Technologies