Nearly 25 years ago, Caterpillar opened a proving ground about 30 miles southwest of Tucson, AZ. The facility consists of large open-air test areas, where Caterpillar conducts field trials of many of its large mining equipment before being brought to market. The proving ground site also includes workshops and an office building.
The Green Valley area outside of Tucson is an ideal testing location for Caterpillar’s mining division. While remote, the site has a large demand for power with employees working on projects ranging from machine tear-downs and builds, to welding, as well as office and administrative tasks. The nearest local utility grid is nearly eight miles away, so the site must rely on its own power generation to run the facility. To generate electricity, Caterpillar uses three Cat C15 diesel generator sets that are designed to run continuously all year long, consuming approximately 250,000 gallons of diesel fuel each year. All together, the generator sets typically run a combined 11,000 hours per year.
Caterpillar holds sustainability as one of its enterprise values and as a key goal across divisions. So finding a more sustainable way to produce the energy needed to run the site became a top priority for managers. With all of this in mind, it was clear that the facility needed to consider an alternate power solution to reduce costs and align with the organization’s sustainability efforts.
Launched in 2015, Cat Microgrid technology offers an integrated suite of environmentally friendly solar panels, state-of-the-art energy storage, and advanced monitoring and control systems, along with Caterpillar’s traditional line of power generation equipment, including Cat generator sets, switchgear, uninterruptible power supplies, and automatic transfer switches.
At the Tucson Proving Ground (TPG), facility managers worked with local Cat dealer Empire Power Systems to install 528 kWp DC (500 kWp AC) of thin-film photovoltaic (PV) solar panels and 500 kW of short-term energy storage in the form of lithium-ion batteries and ultra capacitors to supplement the power generated by the existing generator sets. Empire Power Systems was the original installer of the generator sets at TPG and is responsible for complete microgrid maintenance at the site.
“With the declining cost of renewable energy sources and rapid advances in energy storage technology, the time was right to provide an integrated application for remote power at the Tucson Proving Ground,” says Rick Rathe, general manager of new ventures for Caterpillar’s Global Power Solutions Division. “Cat Microgrid technologies deliver an innovative, financially viable way to incorporate sustainable sources of energy into our existing portfolio of traditional power generation offerings.”
In a hybrid microgrid—like the one at TPG—renewable sources of energy can account for any percentage of the load, depending on conditions. Excess energy produced by renewables is stored for stabilization as well as for use during unfavorable conditions, such as cloudy days and nighttime. Generator sets supplement the system by powering the microgrid when energy from other sources is unavailable.
In the last decade, the price of solar PV panels has continued to decline, which has contributed to an increase in solar installations around the world, especially in areas with a high amount of sunshine. At TPG, like many other regions of the world, the cost to produce solar energy became lower than the cost of producing energy with diesel fuel.
With approximately 320 days of Arizona sunshine per year, TPG is an ideal location for solar power generation. In order to determine the optimal PV array size for TPG, the team used Homer Pro to analyze the load and predict the fuel reduction and cost of electricity both with and without energy storage capabilities. Based on these results and the terrain of the site, the team chose to install fixed solar panels as well as tracking solar panels that follow the movement of the sun throughout the day.
TPG also utilizes the Cat Microgrid Master Controller (MMC) to help monitor its power generation system. MMC manages every power source in the microgrid, helping to smoothly transition from solar power, to energy storage, to generator sets, and back again. By using the MMC, TPG is able to monitor, integrate, and optimize all of its power sources and its production of energy.
With the addition of solar panels and energy storage to its microgrid, TPG expects to reduce its diesel fuel usage by 33% and its generator set operation by 25%. Moreover, the facility estimates saving more than 1,000 tons of CO2 emissions a year. Together this creates a lower total cost of ownership and operation for TPG and aligns with the company’s overarching sustainability initiative.
Besides lowering fuel and operation costs for the facility, the microgrid at TPG is a real-world application of Cat’s latest technology for the commercial market. Available worldwide through the Cat dealer network, Cat Microgrid technologies can be purchased as turnkey installations or design-to-order solutions. This suite of technologies is ideal for a broad range of applications such as powering telecommunications towers, industrial facilities, mining installations, remote villages and islands, rural communities, and off-grid sites like TPG. In addition to the thin-film solar PV panels and energy storage used for TPG, the microgrid offerings from Caterpillar can also include the Cat Microgrid Master Controller, metal-air energy storage, and generator sets powered by heavy fuel oil, natural gas, biogas, or dual fuel.
“Microgrids are a real game-changer for the remote power generation industry,” says Darrin Johnston, customer solutions manager for the Global Power Solutions Division at Caterpillar. “Many of our generator set customers face energy challenges similar to those at our Tucson proving ground. By implementing the Cat Microgrid solution here at TPG, we’re demonstrating how traditional generator set owners can successfully incorporate renewable energy into their power generation systems. This trend is accelerating rapidly as mines, islands, and villages recognize that microgrids can significantly improve their energy security, sustainability, and bottom-line profitability. And Caterpillar is committed to helping our customers capture these gains.”