Editorial, Near-Surface Geophysics for Renewables, Technical Articles, Vol 26,4 Near-Surface Geophysics for Renewables

Introduction to FastTIMES Special Issue: Near Surface Geophysics for Renewables

Editors: Kathleen Dorey, German Y. Ojeda and Geoff Pettifer

The focus of this special edition was to highlight a burgeoning field in geophysics and the sciences in general. The demand for renewable energy is increasing exponentially yet the reality of supplying that energy in a short timeframe has many challenges for the scientific and business communities. In this edition, we wanted to highlight how existing and evolving geophysical methods and technology can help meet the demand for wind and solar energy and carbon capture and sequestration (CCS), a complimentary technology to renewable energy. The three papers focused on here demonstrate the point well. Bruce Samuel, of RPS in Houston, has written a paper about how wind power stations can be better located for stability and efficiency in his paper entitled ‘New Efficient Geophysical Approaches to Defining Windfarm Ground Models’ and McKinley and Balog of THG Geophysics have contributed an article entitled ‘Mapping Depth to Bedrock for Utility-Scale Solar Projects’. In addition Heagy et al., from Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia (U.B.C.) have penned ‘Geophysical inversions to delineate rocks with CO2 sequestration potential through carbon mineralization’ under the direction of renowned geophysicist Doug Oldenburg of U.B.C.

In the windfarm article Samuel points out that wind power is the most used renewable energy source in the U.S. and exceeded the country’s hydroelectric generation by 26 million (MWh) in 2019. Although this trend is remarkable, the rapid expansion of wind power leases in the offshore Atlantic has generated some additional technology and efficiency challenges. Samuel’s paper outlines new technologies and approaches that may now improve the previous windfarm site investigations methods that have been used since the 1970’s. These methods include Ultra High Resolution 3D seismic data acquired in conjunction with Bureau of Ocean Energy Management high-resolution systems (Multibeam, Side Scan Sonar, SBP, and Gradiometer/Magnetometer). This system, the author suggests, can provide a more efficient ‘one and done’ approach to wind development in these areas with one mobilization of equipment but completed in different phases.

The McKinley and Balog paper on utility scale solar project installations emphasizes the need for geophysical technology in addition to the more traditional approach of relying on drilling programs alone. For a larger scale project with subsurface variations, it makes technical and economic sense to employee geophysical technologies such as terrain conductivity mapping (TCM) and ground penetrating radar (GPR), depending of the depth and type of near surface bedrock.  The authors aptly discuss two case studies using these methods, one 1 acre in size and the other a 35 acre site. Each of the case studies discussed have different near surface conditions and imaging challenges. The workflow and benefits of each method for the particular case study are outlined and compared to the costly and data limited drilling only programs.

The third paper in this special edition outlines a potential method of removing CO2 from the atmosphere and how geophysical inversions are instrumental in applying this evolving technology. Heagy et al. emphasize that the subsurface sequestration of CO2 has promise due to the large volume capacity potential as well as a long time-frame for the storage. Their paper describes the method of carbon mineralization of mafic and ultra-mafic rocks as a permanent storage mechanism. They use inverted gravity and magnetic data to delineate the size of the storage site and volume capacity. The paper demonstrates that the inversion is non-unique and geological information assumptions need to be included to generate the best range of results. The resulting volume estimates can aid in important operational decisions such as whether or not to store the CO2 in situ or ex situ, for example.

We’d like to thank all contributors, authors and editors of this special Near Surface Geophysics for Renewables edition of FastTIMES. As this is a rapidly changing field of geophysics we look forward to seeing further advancements, applications and contributions from our profession. We will undoubtedly see how geophysics contributes in other renewable energy areas as the new energy economy expands and develops globally.