What is it about?

This review examines the environmental effects of geothermal power plants throughout their entire lifecycle, from building to dismantling, as the industry expands globally to potentially 21 gigawatts by 2020. Geothermal taps Earth's heat for reliable electricity, unlike intermittent solar or wind, but its impacts vary by technology: dry steam for vapor-rich sites, flash systems (single/double) for hot water reservoirs, binary cycles for cooler ones using secondary fluids, and emerging enhanced geothermal systems (EGS) for deep rocks needing fracturing. Using life cycle assessment (LCA), it compiles data on 1-18 impact categories like global warming (from CO2 emissions), acidification, resource depletion, and toxicity. Key insights: Construction (drilling with diesel) is the primary source of greenhouse gases (10-100+ g CO2 per kWh), while operations contribute site-specific gases like methane or hydrogen sulfide—e.g., Italian volcanic sites reach 670 g CO2/kWh, compared to U.S. binaries at 5 g. Factors influencing impacts include reservoir traits, fluid chemistry, plant design, and data gaps (e.g., no studies for triple-flash or many regions). It highlights low overall energy use (saving 70% vs. fossils) but warns of burdens like water consumption or EGS-induced earthquakes. The paper calls for better inventories, baselines for natural emissions, and standardized LCAs to ensure sustainability, especially in high-potential areas like Asia-Pacific or Latin America facing water shortages.

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Why is it important?

This first-of-its-kind tech-specific LCA compilation for geothermal reveals overlooked variations (e.g., site geology inflating emissions 10x), filling gaps in prior broad reviews amid projected 60% capacity growth by 2020. Timely for climate pledges like net-zero, it counters assumptions of 'zero-impact' renewables by quantifying construction's diesel dominance and ops' gas leaks, urging low-carbon alternatives. Impact: Empowers developers/policymakers to minimize harms (e.g., EGS seismicity), thereby boosting adoption in underserved regions such as Africa/Latin America. This could slash global power emissions by enabling baseload clean energy, creating jobs, and averting eco-burdens for equitable transitions.

Perspectives

In sustainability science, this review advances geothermal LCAs by tech segmentation, exposing data scarcities and methodological flaws (e.g., inconsistent boundaries) that skew comparisons. Broader context: amid renewables' rise, it underscores geothermal's baseload edge but stresses holistic metrics beyond GHG, like land/ecotoxicity, to avoid greenwashing. Future: integrate with socio-economics for triple-bottom-line tools, leverage AI for optimized designs, and expand to hybrids (e.g., solar-geothermal) or direct uses, aligning with SDGs for resilient, low-impact energy in a warming world.

Professor Rosenberg J Romero
Universidad Autonoma del Estado de Morelos

Read the Original

This page is a summary of: Life cycle assessment of geothermal power generation technologies: An updated review, Applied Thermal Engineering, March 2017, Elsevier,
DOI: 10.1016/j.applthermaleng.2016.10.074.
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