Zayo Group Holdings, Inc. announced the completion of the Imperial Valley Dark Fiber Project--a collaborative research effort between Lawrence Berkeley National Laboratory and Rice University and funded by the U.S. Department of Energy--to explore the efficacy of leveraging telecommunications fiber to map and monitor geothermal resources that could enable a low carbon energy future. The Challenge Berkeley Lab and the DOE have been exploring geothermal energy as a renewable alternative to fossil fuels for decades. Clean energy sources like geothermal energy are necessary for producing sustainable energy, reducing emissions, and addressing climate change.

However, these resources are often hidden -- meaning there is no resource surface expression -- and mapping these geothermal resources was historically labor intensive and often cost prohibitive. The Imperial Valley Dark Fiber Project, which kicked off in 2019, sought to develop strategies to better find these resources through seismic sensing via existing telecom dark fiber. The Berkeley Lab-Rice team, in collaboration with scientists from Lawrence Livermore National Laboratory and Scripps Institution of Oceanography, used Zayo's dark fiber network in the Imperial Valley of California--an area already known to be home to many hidden geothermal resources--to test various techniques for mapping geothermal resources.

These methods include Distributed Acoustic Sensing (DAS), a technique that turns Zayo's dark fiber into an array of seismic measurement locations to build a picture of what is underground. In a conventional seismic experiment, only a few seismic sensors can be deployed in one small, targeted area. This often requires significant time for sensor deployment and permitting, while resulting in the use of just a few dozen sensors.

Using existing dark fiber, however, significantly reduces deployment time and increases the number of sensors to thousands. With dark fiber, researchers have access to tens of kilometers of fiber and can measure every few meters, offering unprecedented access that was previously cost prohibitive.