What has mostly been understated or otherwise ignored is that we are not going to solve climate change simply by adding low/no carbon sources as power plants and cars get old – we are forcibly turning down existing power plants and removing gasoline-powered cars while we add a much larger amount of low/no carbon sources. We are not simply evolving towards a new equilibrium by slowly transitioning the energy fleet as it ages. Instead, we are replacing it while it is still running.
This is so different from how we usually think that we are often at odds over simple issues because we are starting from different sides of this question. For example, we are not “adding new electricity capacity with wind and solar,” as most engineers familiar with the power system might think. We are subtracting carbon electricity, and replacing it with low/no carbon electricity.
We want to reduce the burning of fossil fuels, preferably coal. We can replace coal with intermittent sources like wind and solar and still retain reliability for when the wind and solar are not available by keeping the coal plants for when they are needed. In utility terminology, we are retaining capacity (through coal plants) while reducing carbon (by turning them down and replacing the lost energy with solar and wind).
Until we reach a point where we have so much wind and solar that we cannot operate reliably with existing fossil fuel back up, we have no major issue with solar and wind intermittency. After that, we have to add sufficient storage or new flexible fossil fuel backup to add more wind and solar and continue to avoid more carbon emissions.
Meanwhile, we will face a choice about coal. Coal is a big problem in terms of carbon emissions. Critics argue that must continue using it, or use it with carbon sequestration because we have few alternatives. But the recent growth in availability of natural gas may obviate this argument.
Switching baseload electricity from coal to natural gas would cut emissions in half. But it also has a salutary effect on the use of wind and solar. Natural gas is more easily turned on and off, which allows greater flexibility for adding intermittent wind and solar. It is very compelling to imagine us switchimg to natural gas baseload electricity generation while we are scaling up wind and solar, because it will allow us to include more wind and solar while also reducing carbon intensity from our baseload plants.
In parallel, we should develop electric storage via demonstrations of existing technology and through enhanced R&D. There are two clear economical paths to the bulk electric storage that would be suitable to the challenges of wind and solar. One is the thermal storage relatively easily included in solar thermal electric facilities. The other is to have wind and solar electricity drive a
compressor to store high pressure air in large caverns or aquifers. On demand, this air can then be allowed to expand through turbines, with (but eventually without) the help of burning a small amount of natural gas.
Both thermal and compressed air storage are substantial and efficient enough to go a long way towards satisfying the needs of intermittent solar and wind for bulk energy storage as they accumulate past some level, perhaps 30%, on our electricity grid. Other storage is being examined and will play a part: e.g., pumped hydro, flywheels, batteries. Even transmission from daylight or windy areas further and further away can assist grid stabilization as long as transmission losses are contained.
The electrification of transportation will evolve in parallel and will be significant for both climate change and reduced oil dependence. Electricity is already cheaper than oil to move cars (10 c/kWh is about 1 dollar per gallon equivalent per mile). What we do not have is the batteries and then the cars to use this electricity. But as gasoline cars are replaced with those that can use electricity, we will use somewhat more electricity (much of it from wind and solar), but save both oil and carbon emissions (and perhaps driving costs). But it will be another case of replacing “before its time” infrastructure that works (oil and cars) and is mostly paid for, with a new infrastructure that has more sustainable characteristics.
This replacement of infrastructure “before its time” is the added cost that is being talked about when climate change is being discussed. It is not the cost most people think – the cost of the new technologies versus the old ones, on a steady-state basis. That cost will be fairly small, even negative, and is largely unpredictable due to technology progress uncertainties and fuel price uncertainties. Instead, the cost that stands out is the one of making the fast change from today’s equipment to the new equipment.
We are replacing current infrastructure and incurring added costs to do so, because that is the only way we can rapidly turn down fossil fuels.