All of the Above:

A Matter of Common Sense

One recurring discussion we seem to face is what the mix of energy sources should be.  This discussion has become particularly important as the drive to reduce carbon emissions grows, and as the costs of renewable energy simultaneously seem to be plummeting.  That combination of factors has tempted some to envision a world powered entirely by the sun and the wind.

Many of us in the energy field have long tried to challenge such a scenario.  Experience has taught us that new problems often emerge as the use of a technology increases.  I recall many years ago reading a "look back at history" type of article that lauded the fact that those newfangled automobiles would solve the pollution problems created by horses in the city.  No one recognized then that automobiles would bring another type of pollution, and that, years later, we would spend time, money and energy to address that pollution.

Therefore, I was very pleased to see a very rational discussion of the issue entitled The Environmentalist Case against 100% Renewable Energy Plans.  The article draws a distinction between what is technically possible and what is optimal, thus transforming the argument from whether or not something can be done to whether it should be done.

The article also takes on the difficulty of achieving a 100% renewable power supply.  Although proponents of such a scenario cite various storage possibilities (as well as grid interconnections), the article points out that energy storage is not just a daily problem.  Wind patterns are seasonal, and there can be extended patterns of wind variability for other reasons.

In fact, shortly after I read this article, I saw some statistics from the Energy Information Administration (EIA) that graphically showed a 5-month period at the beginning of 2015 where the capacity factors of wind plants on the West Coast were lower than the average of the previous 5 years.  The EIA notes that capacity factors vary non-linearly with wind speed, so small decreases in wind speeds can result in much larger changes in capacity factors.

As a result of these variations, a huge investment in storage would be required in order to assure a reliable energy supply during extended periods of low wind speeds.  Yes, wind and solar mixes can complement each other, and yes, grid interconnections can bring renewable-generated electricity from far away, but each of these scenarios has costs and limitations as well.  Reliable baseload sources can do the same job much more efficiently.

The article also takes on some of the other, less technical, issues.  In particular, it notes the irony that eliminating nuclear power in favor of wind and solar energy requires much more transformation of the landscape to produce the same amount of energy, which draws opposition from other environmental groups, as well as from people who don’t want wind turbines marring their scenic views.

The article raises other points as well.  For example, it notes that all energy technologies are evolving, so the projected benefits of advanced solar or wind systems should be compared to the those of advanced nuclear systems and advanced carbon capture and storage systems, not to present technologies.  This is a point that I have found is often glossed over--by proponents of all technologies.

There are probably other points that the article could have made.  It comments on the small footprint of nuclear power plants compared to wind and solar plants, but not on the greater amounts of materials needed for renewable plants producing the same amount of power, and the environmental impacts of mining and manufacturing those.  Or of the need for specialized materials such as rare earths.  It mentions an allegation that mining uranium is energy intensive (and therefore, generates carbon at the front-end), but it doesn't challenge that assumption or compare the front-end energy demands with those for renewable energy sources.    

The article emphasizes that replacing some non-emitting sources with other non-emitting sources gains nothing environmentally, while adding a lot to the cost.  It concludes that the best option is a mix of energy technologies, noting that the optimal mix may vary, depending on location. 

In summary, the article makes a good start at looking at our energy mix holistically.  In particular, it helps make the case of why something that is technically possible (maybe!) is not necessarily the best path to pursue, and suggests how we should be approaching decisions on our future energy supply.

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