(413g) Life Cycle Analysis of Geothermal Energy Extraction

Vasquez, V. R. - Presenter, University of Nevada, Reno
Hanbury, O. - Presenter, University of Nevada, Reno

As petroleum resources dwindle, many alternative transportation fuels
have been proposed as replacements.  One of the most versatile of
these is electricity, which is source agnostic from the perspective of
the vehicle, allowing any power generating process, either traditional
or renewable to be used.  It is then important to assess the
externalities of these sources to meet modern emissions standards.  In
this work, we use a cradle-to-grave LCA approach to evaluate the
life cycle issues of geothermal energy extraction (hydrothermal reservoirs) and compare
it to the environmental impact of competing energy and fuel sources.
For comparisons purposes, we use the results of modeling frameworks
such as GREET to estimate the baseline environmental impact of more traditional
fuel pathways (i.e., petroleum or biomass-based). These are used to
evaluate other fuel candidates or validate the potential renewable
energy sources from an environmental impact perspective.  
This work follows ISO 14040 standards for life cycle analysis applied
to geothermal energy.  This breaks down energy production into the discrete stages of drilling,
production, and site reclamation and allows for further extensive
modularization.  The environmental impacts from geothermal energy
depend heavily on the chemistry of the reservoir, the power facility
equipment, and the manner in which the spent fluids are handled.
These factors are summed over the life of a facility using Monte Carlo
simulation, to give an estimation of the total impact that a
geothermal facility will have in its lifetime.  The results show that
while the impacts of even renewable energy sources are non-negligible,
their use can reduce the influence transportation has on the environment.