Finnish physicist Jani-Petri Martikainen has authored an article on the blog Brave New Climate questioning the ability of renewable energy sources to provide 100 percent of global electricity generation. The following was posted as a comment.
Thank you for the post. While your method has some technical flaws (some have already been pointed out by others above, I’ll address some others at the end), the largest problem with this post and your previous post is more fundamental.
The fundamental problem appears to be a confusion between the concepts of energy and capacity. From the perspective of someone interested in reducing the use of fossil fuels and the negative externalities associated with their use, energy concerns are paramount and capacity concerns almost entirely irrelevant. A fossil power plant that is turned off, waiting to be started up when it is needed to produce electricity during periods when electric demand exceeds the supply of variable renewable resources, produces no emissions and has no fuel use.
Arguing that keeping some fossil-fired power plants around to run a small number of hours per year when they are needed undercuts the emissions savings of renewables is the same fallacy as arguing that a person who rides a bike to work achieves no emissions savings because they still have a car sitting unused at home. In both cases, fossil fuel consumption and harmful emissions are only associated with the use of the fossil-fueled device, and there are no emissions associated with the mere act of keeping those devices around. As a result, your figure that under a wind and solar future we will need to keep enough dispatchable generator capacity to meet 89% of our current peak demand is entirely meaningless from an emissions and fossil fuel use perspective, as simply keeping those plants around to be run during a limited number of hours per year has no emissions or fuel use impact.
In your analysis, wind and solar were able to provide 81% of the electricity consumed by society, which is the important number from an emissions and fuel use perspective. In your previous wind-only analysis, 79% of electricity came from renewables. Both are remarkable achievements, as society’s use of fossil fuels for electricity production would be reduced to around 20% of our fuel mix. In the U.S., fossil fuels are used to produce around 70% of our electricity, so reducing that figure to 20% would cut electric sector fossil fuel use and the associated harmful emissions of pollutants like carbon dioxide, mercury, sulfur dioxide, nitrogen oxides, etc. by a factor of three or more. Moreover, in many parts of the world flexible hydroelectric power plants would be used to provide much if not all of that remaining 20% of generation, bringing electric sector fossil fuel use and emissions down to near zero. Furthermore, any fossil generation used to provide capacity and flexibility would most likely come from flexible natural gas power plants that are drastically cleaner than the inflexible coal power plants that dominate the world’s electric mix today, so emissions would be reduced even further.
You might have tried to make an argument that a power system with 80% of electricity coming from wind would be excessively costly, although that line of argument would have been unlikely to meet with success. Even at today’s extremely low natural gas prices, wind energy is highly competitive with other energy resources. http://bnef.com/PressReleases/
In many parts of your post, you seem to be attacking a strawman argument that wind and/or solar will or must meet all of our electricity needs, like when you write “Currently the mirage of purely unreliables based energy production essentially maintains the use of fossil fuels for as long as the eye can see both for technical and financial reasons.” No prudent person has ever argued that any one energy source should meet all of our electricity needs, given that different resources naturally have different capabilities to provide the power system with capacity, energy, and flexibility, (for more, see http://www.awea.org/
As far as the more technical flaws in your methodology, the main flaw is that your data sources do not adequately capture the geographic diversity you would get from the large-scale deployment of wind energy you are attempting to model. Taking data from a relatively small amount of wind deployed in three relatively small geographic areas (Ireland, the small stretch of the Columbia Gorge where BPA’s wind is deployed, and Southeastern Australia) and simply linearly scaling up the total greatly underestimates the true geographic diversity of a much larger amount of wind deployed over a larger geographic area (see http://www.nrel.gov/docs/
Xcel sets world record with 55.6% wind penetration, November 28, 2011
Wind research generates savings for large utility, November 14, 2011
Notion of other power sources being variable, too, gains traction, August 30, 2011
After a scorching week, wind power lessons from the Texas heat wave, August 11, 2011
Wind helps meet new Texas record for electricity demand, August 4, 2011
Wind energy integration: Some fundamental facts, June 23, 2011