Prepared by: Thomas Kinjorski, Mitchell Krueger, Alex Riebe and Ben Steinbach
Background and Vision:
The MTU College of Forest Resources and Environmental Science (CFRES) in partnership with the Michigan DNR are developing an experiment focused on mitigating the deleterious effects of white-nose syndrome on bats in abandoned mine hibernacula. Specifically, CFRES and DNR aim to lower the temperature within mines to reduce the growth rates of the fungus responsible for white-nose syndrome, while maintaining temperatures adequate for bat hibernation. The focus of this project is to develop a system to help implement the experiment by conditioning and pumping in external air and is to be completed by Spring 2024.
This semester the goal is to create a data acquisition device and to set up different power generation tests. These systems will then be tested over Winter Break to inform decisions relating to the cooling device in the Spring.
Developments:
Power Generation
To power a system powerful enough to cool the volume of the Mead Mine, a robust power generation system is needed. The initial research done into off-grid power solutions concluded that solar would be the most cost-effective and logistically viable solution. After a visit to the mine site on September 21, we chose two locations to install test systems. The questions we needed answered before developing a proposal for a finalized array were:
- How much efficiency would be lost by mounting the solar panels vertically instead of the optimal 30° – 50°? Vertically mounted panels require less maintenance and would reduce the need for snow removal. The test systems use two panels set at 90° and approximately 60°.
- Which location will provide the highest year-round solar irradiation? The test site is surrounded by trees and the Porcupine Mountains which will interfere with light availability. To test this we used a device called the Solar Pathfinder.
The test panels were mounted on 4 x 4 posts in the two locations that seemed the most suitable. These locations were chosen using data gathered from the Solar Pathfinder. The Pathfinder displays the percentage of sun exposure for each month as well as the angle of surrounding obstacles from the horizon. Figures 2 and 3 show the device readouts at the two sites. During the important months of December and January, test location 2 will be exposed to direct sunlight for 64% and 78% of the day respectively. For comparison, the month of July has an exposure percentage of 98%. Test location 1 has greater exposure during the spring and summer months but December and January sit at 36% exposure. While test site 2 seems to be the best candidate for a final recommendation, data gathered from the power DAC at each test site will influence the final decision.
Figure 1: Test System
Figure 2: Test Location 1 Figure 3: Test Location 2
Power DAQ
Originally, our goal was to find an off-the-shelf solution to quantify the power production of potential generators. Unfortunately, there was no such solution that met our power DAQ needs. This resulted in us constructing our own solution. Our power DAQ was designed to calculate power by measuring the voltage through a simple voltage divider and measuring current through a hall effect sensor. It uses an Arduino Nano to schedule data collection, calculate necessary values, and store time-stamped power values. EEPROM storage was our original solution for memory, but we reconsidered and are planning to use an SD card instead. The whole of the circuit fits within a 6×6 IP65 box which will be mounted by the solar panels. Each box will be equipped to measure both of the solar panels. We plan on measuring the original solar panels placed by the DNR last year and both of the two selected locations over Winter Break.
Mine DAQ
The DAQ has fallen to a lower priority than the Power Generation System and the Power DAQ. The Mead Mine is seasonally accessible, so everything we had to do on-site became our top priority. As such, the Mine DAQ, intended to collect temperature and humidity data, has not yet been built. A prototype schematic has been created, and parts acquired, so we expect the first physical prototype to be done early next semester.
Mine Modeling
On November 23rd, the Douglass Houghton Student Chapter of the National Society of Professional Surveyors came with us to the Mead Mine and gathered point cloud data. The point cloud data can be found by following this link. Next semester we intend to find MTU faculty or students that can run simulations on this data to get a better understanding of how much energy we need to put into the system to cool the mine. The surveyors were only able to gather data on approximately 50% of mine before the DNR had to lock up the mine, but the gathered data should be enough to get a better idea of the necessary cooling system specifications.
BOM
Functional Requirements:
- The entire device will have design files originated entirely from free and open source software. (5%)
All parts of the device are readily available. No formal design files have been created yet because of insufficient testing, but will be documented in KiCAD once they are implemented. All software coding will be done in either Arduino coding language or in Python.
- The data acquisition device will be able to measure relative humidity and temperature. (10%)
The DAQ will be using SHT-30 Mesh-protected Weather-proof Temperature/Humidity Sensor to collect mixed humidity and temperature data. It will be using a Series O-4 Outside Air Temperature Sensor to collect solely temperature data. It is not expected that there will be a large change in relative humidity throughout the cave so the resolution of humidity sensors will be much lower than that of the temperature sensors. The Series O-4 sensor is much more robust and cheaper than the SHT-30 sensor so the sensor net will be made up of mostly O-4 sensors with SHT-30s mixed in to confirm the relative humidity consistency.
- The data acquisition device will be low powered and efficient. (5%)
The DAQ has been designed to be low powered, but has not yet been tested. This has also been moved to a lower priority because we expect that a larger solar array (or other power generation source) can be constructed than previously thought.
- The data acquisition device will be robust and withstand the outdoors with minimal dependance on human interference. (10%)
Component choice and DAQ housing leads us to believe that the DAQ will be able to withstand the outdoors. The mine is also more hospitable than expected with the main environmental hazard being standing water (which remains relatively consistent throughout the year according to the DNR) on the cave floor and light water dripping from the ceiling . We have selected a housing for the DAQ that meets the IP and NEMA standards to meet the dripping water hazard and plan on using an easily constructed structure to keep sensors and DAQ above the standing water level. This has not yet been tested.
- The data acquisition device will be simple to use and easy to access data from. (10%)
The DAQ is designed to use a Pi Zero as its primary microcontroller. Pi Zeros come with SD card compatibility. The data collected by the DAQ will be stored on this SD card and accessing the data is a simple SD card switch. The DAQ has not yet been built.
- The power used by the data acquisition device will be quantified. (5%)
The power used by the DAQ has not been quantified.
- Potential power generation systems have been identified and a proposal created. (20%)
Solar has been identified as the sole ‘green’ energy source. Panels needed to implement the full scale system have been found, but were unable to be purchased. Due to size and location restraints, we are not able to install these. Instead we will use smaller panels to determine the ideal location and number of panels needed.
- Potential power generation systems are set up on site and actively collecting data on their production. The findings are well documented. (20%)
Solar Test Arrays have been set up on site. The Power DAQ is in the final stages of testing before installation. Data collection will be done over Winter Break.
- Potential cooling systems have been identified, researched, and documented. (5%)
Due to the size of mine and the nature of bat hibernation, air has been identified as the best cooling system. Further testing is planned for next semester with the newly gathered point cloud.
- A weather station will be placed outside the cave if deemed feasible. (10%)
A weather station has been deemed infeasible.
Value-Added Goals:
- Create a flowchart/decision tree that other places around the country can follow. (10%)
No flowchart/decision tree has been created.
- The data acquisition device will be of a modular design to allow for extra sensing capabilities in the future. (10%)
The DAQ is of modular design. This is done by implementing a CAN based communication system that allows for easy additions to the sensor net. Each sensor block can be connected to the net as long as it has a unique address.
- Data acquisition device can report errors in the system to the user. (10%)
The DAQ is at this point unable to report errors to the user.
- Kalman/IIR filter implemented to improve data acquisition. (10%)
No Kalman/IIR filter has been implemented at this point.