Is All Renewable Energy by 2050 Realistic?


6/1/2017 by David J. Petersen

Is All Renewable Energy by 2050 Realistic?
Portland Mayor Ted Wheeler and Multnomah County Chair Deborah Kafoury recently pledged that the City and County will run exclusively on renewable energy by 2050. Is this for real? Can it be done?
To answer that, this post focuses on science and economics. Policy and human nature are of course huge hurdles also, but I want to know – assuming there is the will, is there a way?
Going 100% renewable basically requires electrifying everything. This mostly means transitioning the energy source for transportation and heating from carbon fuels to electricity. Of course, electrifying everything will cause a huge increase in demand for electricity. Electricity from wind and solar are the best carbon-free options, and they are limited only by the amount of the earth's surface dedicated to their generation. But they are not "dispatchable," meaning they are not always available when needed.  
So how do we get carbon-free dispatchable power? That is the crux of the dispute as to whether 100% renewables is achievable. For a real in-depth explanation of the issues, I strongly recommend the Vox article linked above. But if you want the CliffsNotes version, read on.
  1. We can get to about 60% renewables now with existing technology. (For comparison, we are currently at about 5%.) Forecasts of the penetration of wind and solar into the energy mix have consistently been pessimistic, so if the conventional wisdom is now 60%, it's probably a bit higher than that.
  2. Getting to around 80% penetration requires a large scale investment in some combination of energy storage, a vastly improved transmission grid or (paradoxically) a lot of new non-renewable power plants. That's because you have a lot more variable power that needs balancing with dispatchable power. Current models estimate, for example, that 80% renewables would require the ability to store about eight to 16 weeks' worth of electricity. Our current nationwide storage capacity? About one hour. Still, 80% is probably achievable with continued development of storage technology and the use of new, safer nuclear power technology for dispatchable power. Without nuclear, it becomes much more difficult.
  3. Getting into the 90% range and above requires admitting that we don't know what we don't know. In other words, this only happens if technology changes in ways we cannot presently envision. What we do know, however, is that technology will change in unanticipated ways – it always does. So the worst thing we can do is to plan for the future based only on what we know.
  4. To get to 100%, the costs are just off the charts.
So, can Portland or Multnomah County get to 100% renewables? Probably yes, because they are only a small corner of the grid and the overall demand in those jurisdictions is small. That means 100% renewables here would be offset by impacts somewhere else on the system, so taking credit for the whole 100% would require a bit of conscious ignorance. Still, it is a laudable goal and worth the effort, if for no reason other than to show it can be done.
Can our electrical grid as a whole get there? Probably not, although we can get pretty darn close. And given our current 5% renewables and one-hour storage capacity, 100% renewables isn't anything we will see on the horizon anytime soon.