Tricky Questions on Solar Energy: Part Two

As a doctoral student with a dissertation on solar energy infrastructure and development, I’m continually asked a number of questions from those that are skeptical, or just curious, of the potential of solar energy in creating a more sustainable energy portfolio for the United States. This post, the second of two on this topic, tackles three more thought-provoking questions about solar energy in the United States.

How much is enough?

There are two basic schools of thought on the impact renewable energy will have on our overall energy demand; one, that it will reduce our dependence on traditional energy sources, or two, that the additional generation capacity will simply allow us to increase our energy demand with a lesser environmental impact.  Answering this question is necessary to answering the subsequent one of “how much is enough?”  In 2014, a report from the White House on Obama’s “all of the above” energy solution  states that, at the time of publication, the United States is becoming more energy efficient, defined by the amount of energy required to produce one dollar of GDP, but because our GDP continues to rise, the total sum of energy required to sustain our GDP projects will also continue to increase. The report states that in 2007, roughly 2% of our energy came from non-hydro renewable resources, and that had tripled to 6% in 2013.  According to the same report the Interior Department is “on track to permit enough renewable energy projects on public lands by 2020 to power more than six million homes; the Defense Department has set a goal to deploy three gigawatts of renewable energy … by 2025; and, as part of the Climate Action Plan, the Federal Government overall has committed to sourcing 20 percent of the energy consumed in Federal buildings from renewable sources by 2020.”  To keep up with growing populations and projected continued increases in GDP, production goals will also need to continue to increase at a faster rate to ensure a reduced dependence on traditional energy sources.  

Is it green?

This is the most paradoxical – and thought provoking – of all the questions I have heard on solar energy, and one that is best answered with the suspect response, “It depends.”  I once saw a t-shirt that said “To make apple pie from scratch, start by inventing the universe,” and this feels like a similar conversation, as one first has to answer the underlying question, “What is green?” The answer is different for every country, corporation, and citizen, and is one that is constantly evolving as we better understand the impact of our actions and the resiliency thresholds of the planet moving forward.   

Several years ago I took a course on lifecycle assessment modeling and the biggest takeaway lesson was that the boundary definition was the primary driver of a project’s, item’s, or entity’s life cycle impact or carbon footprint, and was requisite for comparison.  This question really isn’t about a definitive yes or no answer, but about being an educated and thoughtful consumer of information. Depending on your perspective, the true “greenness” of “environmental footprint” of solar energy can include, or not include, such disparate factors as the number of airline flights traveled by company executives (perhaps as they conduct meetings with environmental consultants), the materials used to construct the factory where the components are built, the type of energy used to power their equipment, and the methods of outreach used to educate the public about the impacts of a proposed project, in addition the project’s location, design, construction, and operation practices.  Many solar plants supplement solar energy generation with natural gas, or sometimes even coal-fired power plants, particularly at night or on cloudy days, as it ensures constant and consistent energy generation, while other plants truck in countless gallons of water for construction and maintenance; many view these elements of solar energy production as particularly hypocritical.

What about the birds?

One particular aspect concerning the environmental friendliness of utility-scale solar energy plants that seems to garner much controversy is its impact on bird (avian) communities. Heliostats – the mirrored panels used in concentrated solar power plants - concentrate the sun’s energy and refocus it back toward a heating element; this creates a phenomenon called solar flux. Argonne National Laboratories reports that solar energy infrastructure can directly impact avian species either through collision (birds flying into a structure) or through solar flux, although fatalities from solar flux have only been observed at facilities that concentrate solar energy, such as trough, dish, or power tower facilities. Fatalities from solar flux have not been observed at photovoltaic fields.  A detailed report of avian impacts from solar energy infrastructure prepared in 2015 by Argonne and the National Renewable Energy Laboratory (NREL) can be found here.  Avian fatalities can be a major concern, and liability, for developers as well, as most species in question have federal protection under the Migratory Bird Treaty Act, administered by the US Fish and Wildlife Service. 

Solar flux by itself does not create heat, but when an object absorbs light energy, that object will radiate heat, and the mirrored panels that gleam in the sunlight can attract birds and bats, creating a potentially dangerous situation for unexpecting avian wildlife. However, many solar energy skeptics harbor horrible images of thousands of birds and bats getting zapped mid-air as they fly above a solar energy facility, which typically isn’t true. For example, the Ivanpah Solar Energy Generating Facility (ISEGS), located in the Mojave Desert near the California/Nevada state line, reported 321 avian fatalities in the first half of 2014, 133 of which were related to solar flux, while a contesting study estimated that number anywhere from 1,000 – 28,000 per year. 

The wide spectrum of estimates makes it nearly impossible to determine anything except that solar energy, like nearly all man-made additions to the earth, will undoubtedly cause some direct avian fatalities. More importantly, however, is whether avian wildlife communities, and society, can accept these fatalities, as we have done with other types of infrastructure and activities. For example, a 2010 study from the University of Nebraska estimates that outdoor cats worldwide have been responsible for the extinction of 33 bird species, while many others contested the study’s methodology and dispute those conclusions. What does seem to be clear is that fatalities caused by solar energy generation are not nearly as numerous as those caused from other types of energy generation as well as those from more mundane causes, such as low-story buildings, vehicular traffic, and even household cats. 

Nikki Springer is an ISPS Graduate Policy Fellow, and is a joint degree student working toward a PhD at FES and a MBA at SOM.  Her research focuses on the interplay of environmental regulation, corporate incentives, and ecosystem planning in the context of national-scale infrastructure.