Earlier this year, I had the opportunity to attend Apple co-founder Steve Wozniak’s keynote presentation during the 2014 Energy Thought Summit in Austin. Wozniak mostly spoke about his experience developing early versions of the personal computer, and lessons from his experience that might translate to the energy industry. When asked what advice he has for the energy innovators out there, he pressed the importance of asking whether green energy is actually all that green:

I think we get fooled a lot by what devices are “green” in terms of pollution and the like…I’m all for wind power and solar but they say there’s not enough land space and they’re a tiny tiny bit of our energy needs and they cost more. Costing more is a difficult factor because the amount that something costs… is equal to all the parts that are in it plus the energy to combine them… If you don’t have control over the type of energy, it’s equivalent to the pollution. Cost equals pollution… So we fool ourselves… I love wind if it could only produce more per land space that it uses. Solar thermal’s really good but if it costs twice as much as burning coal the manufacturing cost was all dirty energy to produce clean energy…If you had a solar cell that took two Joules of dirty energy to make it and it only returned one Joule of clean energy in its life—it’s a loss…We fool ourselves.

Using an analogy that assumes the environmental impact of an energy technology scales with its cost, Wozniak calculates that some renewable energy technologies might produce more overall emissions than fossil fuels because they cost so much. He urges the energy innovators out there to heed his warning.

Wozniak’s assumptions sound reasonable at first blush. In fact, they’re reminiscent of a method of environmental accounting called Economic Input-Output Life Cycle Assessment. However, when you compare his conclusions to reality, it turns out they are far from the truth. Fortunately, Wozniak is not the first person to ask if clean energy is really clean.

How to quantify the overall environmental impact of energy technologies has actually been a subject of the academic literature for some time. Engineers use a process called life cycle assessment to count up all of the interactions between a complete energy system and the environment. For example, life cycle assessments of electricity generation typically consider power plant raw materials extraction, plant construction, fuel extraction, fuel processing, fuel delivery, fuel combustion, electricity transmission, and other upstream and downstream processes in order to paint a complete picture of the energy and emissions required to produce and deliver a unit of electricity.

After years of research, the data is in on the relative environmental footprint of renewable versus non-renewable energy technologies. A recent report by The Intergovernmental Panel on Climate Change (IPCC) reviewed over a hundred existing life cycle assessment studies analyzing the greenhouse gas (GHG) emissions from electricity generation technologies. By comparing one study to another, the IPCC developed a probability distribution on life cycle GHG emissions from each of the most common electricity-generating technologies that includes the effect of varying assumptions and scenarios (e.g. different types of coal, different natural gas generator configurations, different solar panel technologies, etc.).

The Intergovernmental Panel on Climate Change (IPCC) reviewed over a hundred life cycle assessments of electric power production to develop probability distributions on the overall greenhouse gas (GHG) emissions from the most common generating technologies. The bars indicate the expected range of life cycle emissions from each technology based on the count of estimates given in the table below. The red diamonds correspond to emissions from technologies using carbon capture and storage (CCS). (Source: IPCC)

The IPCC’s results are unequivocal: total GHG emissions from natural gas, oil, and coal electricity are far greater than those from any renewable energy technology.

Even if it takes more energy and emissions to build a solar farm than, say, a natural gas power plant, the fact that the solar farm produces zero emissions during operation causes it to be cleaner overall. The same holds for all other forms of renewable energy—and nuclear too.

Given the facts, I ask myself where Wozniak’s incorrect notion about energy originated. He is hardly the first person to draw false comparisons between renewable energy and fossil fuels. Perhaps we are drawn to the idea that the energy system in all its complexity might cause renewables to be dirtier than intuition suggests. More likely, this notion originated in the minds of those more interested in concealing the truth than revealing it.

Regardless, public figures like Wozniak should refrain from suggesting that emissions from renewable energy are comparable to those from fossil fuels—the facts are out there and they clearly show natural gas, oil, and coal electricity emissions vastly exceed those from renewables and nuclear.


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