Now, You See It…But with Geothermal, You Don’t Have To
It’s funny how some people advocate for more renewable energy sources…as long as they end up in someone else’s backyard. The primary reason for this attitude is that renewable energy sources such as wind and solar-thermal (those acres of mirrors with a giant tower in the center) have what is termed high “visual impact.” Large-scale projects using these technologies decidedly alter the landscape, or at least one’s view of it.
Minimizing the visual impact of certain renewable energy technologies is often a challenge because of energy density, siting and the physical nature of the technology.
Wind turbines are a good example of the energy density challenge. It takes a huge amount of surface area to capture the relatively small amount of energy provided by the wind. Creating lots of surface area means giant wind turbine blades and lots of them. To have the same electricity-producing capability, a wind turbine farm might occupy more than a hundred square miles as compared to the few square miles of land a conventional 100 MW geothermal power plant might occupy.
Siting refers to the physical location of a generating source. Solar-thermal projects are often placed in flat, wide-open spaces to receive maximum sunlight. Wind farms are typically located in areas where with the wind is least obstructed which is often on higher elevations and hilltops.
The physical nature of wind turbines is to be tall in order to use larger blades for more surface area as well as taking advantage of stronger wind farther from the ground. The towers used in solar-thermal projects also need to be tall so that there is a direct line of sight from each of the thousands of mirrors to the thermal collector.
One emerging renewable energy source that has a relatively minimal visual impact is Enhanced Geothermal Systems or EGS.
With EGS, the energy density of hot, underground rock formations is much higher than that for wind or solar collection. Moreover, all of the energy collection essentially takes place underground. From a visual impact perspective, there isn’t much of an Enhanced Geothermal System to see.
The most critical siting issue with EGS is the location of the wells for injecting water down to the hot rock formations and for recovering the hot water or steam. Once drilled, the wellheads (like large valves) and the hot water or steam gathering system pipelines are the only evidence the wells are there. The EGS electricity generating plant may be located some distance from the wellheads for practical, environmental or visual impact reasons.
The largest visible portion of an EGS electricity generating plant is the generating facility. Since Enhanced Geothermal Systems require no boiler, smoke stack, tall cooling towers (with their billows of steam) the facilities overall have a quite small footprint and a low profile compared to other conventional and renewable electricity generating installations.
These characteristics all serve to make Enhanced Geothermal Systems one of the least visually obtrusive among all of the types of electricity generating sources.