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Tuesday, June 13, 2017

Bounding the Renewables-Nuclear Debate

Figure 1: From NREL Renewable Electricity Futures Study

Very few people out there are arguing for a 100% nuclear future, and most are not arguing for a 100% renewable future. When we toss the extreme views out, the debate is over how much of what.

If you bound your debate to electricity generation in 2017 in a given geographical area, say, Seattle, you get:

Hydro 87.3%
Nuclear 4.7%
Wind 3.1%
Coal 2.1%
Natural Gas 1.3%
Biogas 1.1%
Other 0.4%

Not bad. Who said you can't cost effectively decarbonize with renewables (when 87% comes from hydro)? Doing that with wind and solar, on the other hand, remains an untested hypothesis.

If you bound your debate to electricity generation in 2050 in the continental United States you might get what you see in the lower half of Figure 1 above, which encapsulates the four-volume mega-study from the National Renewable Energy Lab to replace 80% of our electricity generation with "renewable" sources.

If you can't trust the NREL to come up with a competent study biased to favor renewable energy, who can you trust?

Some things to note about that study:
  1. If their assumed reduction in electricity use fails to pan out, the 50% that is wind and solar combined, drops to 36% of electricity use, or about 14% of total energy and for all renewables combined about 57% of electricity, or about 23% of total energy.
  2. If the massive expansion of biomass (to displace baseload coal) does not materialize, the 80% value for all renewables drops to about 65% for electricity, making renewables about 26% of total energy.
  3. If neither the energy reduction or biomass expansion pan out, renewables will be providing about 46% of electricity use or about 18.4% of total energy use.
  4. If their massive expansion of storage does not pan out, the entire study unravels. 
  5. Note that nuclear is still part of the solution.
  6. Note that had they displaced coal with nuclear (making it the second largest low carbon source behind wind) they would have far fewer emissions.
  7. The study was not trying to find the lowest cost per unit emission.
  8. The study was trying to find the lowest cost path to 80% renewables (not the lowest cost period).
  9. Had they been looking for the lowest cost per unit emissions, nuclear would have expanded to displace coal.
  10. All results are purely theoretical (it's just a study).
Thanks to the recent bankruptcy of some nearly completed nuclear power projects, many wind and solar enthusiasts think that we should leave new nuclear out of discussions bounded by electricity production in the United States. We have lost the expertise to do it cost effectively and if we want to build our own, we'll just have to have to climb back up the learning curve.

Fair enough for now but the costs of integrating wind and solar will eventually begin to climb as the last of the low hanging fruit gets picked, their financially destabilizing sporadic power gluts grow, transmission costs rise, and subsidies end. And as shocking as this may sound, despite the low LCOE values for utility thin film in sunny places and wind in windy places, there is no evidence that wind and solar are reducing citizen's electric bills anywhere in the world. Germany would have gotten far more bang for their buck had they expanded nuclear instead of renewables.

If we expand the boundary of our discussion in the United States to include emissions from all energy use, nuclear comes back to the table. See Figure 2.

Figure 2: NREL study to optimize use of nuclear, wind, and solar

Because assumptions 1-4 are very unlikely to all materialize, we can expect renewables to fall far short of what needs to be done to decarbonize. Come to think of it, they fall far short even if all assumptions materialize. Obviously (or not) because coal is generally used to provide steady baseload, wind and solar are not displacing it (they are anything but steady). They are displacing natural gas. Natural gas has about half the emissions of coal. Nuclear on the other hand, tends to go toe-to-toe against coal, providing twice the emissions reduction per unit energy of wind and solar. To recap; all else being equal, when it comes to emissions reductions, every unit of nuclear added will tend to eliminate roughly twice the emissions of wind or solar.

The potential failure of assumptions to materialize is a measure of risk. If you want to minimize risk, you would maximize use of a source that has a long  history of safely providing low carbon energy. In short, you would displace coal with nuclear and use wind and solar to minimize the use of gas.

When extending your boundary to include the planet, globally, nuclear is, to date, holding its own, especially once Japan finishes restarting its nuclear. Some countries are still building low cost nuclear at a very fast pace (South Korea's KEPCO is, on average, building a 1400 MW nuclear power station for the UAE about every two years).

The difference between the red and green curves in Figure 3 demonstrates the damage done to low carbon energy production by multi million-dollar fear mongering antinuclear groups like the Sierra Club, Greenpeace, UCS, and the NRDC.

Figure 3: World Nuclear Output TWh Adjusted for German and Japanese Closures, Relative to Wind, and Solar (Data from 2016 BP Statistical Review)

Look at the red and purple curves again in Figure 3. Antinuclearists cynically view it as a contest between nuclear and renewables. They're waiting for the day when the green and purple curves cross but they're kidding themselves because those curves don't represent equal emission reductions. The green curve represents roughly twice the emissions reductions. The convergence of those two curves represent  a period of no progress in emissions reductions. In reality, nuclear is our biggest and most powerful ally in the battle against climate change.

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