by Planning Engineer
There seems to be a belief that increasing the level of wind and solar projects will make subsequent progress with these resources easier. Nothing could be further from the truth.
Increasing penetration levels of wind and solar is like a Sisyphean task, except that it is worse. The challenge may be better understood as akin to pushing a huge rock which is getting heavier and heavier, up a hill of a steeper and steeper slope while the ground below gets slicker and more unstable. The problems associated with increased penetration swamp any potential benefits that might be achieved through economies of scale.
The bulk power system has traditionally been strong and very robust. There are generally not significant problems associated with adding small system elements (small amounts of wind and solar) which lean on the system, rather than support it. The system has a limited ability to absorb wind and solar power and can use it to displace generation which relies on costly fuels. But at higher penetration levels this ability is greatly reduced and the economics can degrade and even reverse. Listed below are some reasons why increasing the penetration levels of renewables will lead to rapidly increasing costs as well as rapidly decreasing reliability.
1)Wind and solar do not readily supply essential reliability services. Conventional generation has characteristics that support the stability and operation of the grid. They have inertial mass and spin in synchronism with the wave forms powering the system while readily providing voltage and frequency support. As wind and solar make up a larger percentage of the generation resource base we see an erosion of these desirable characteristics. Some argue that electronic emulation can serve to compensate for the loss of these characteristics but it is costly and the results are inferior. Previous writings going into detail on this topic include: https://judithcurry.com/2015/05/07/transmission-planning-wind-and-solar/ https://judithcurry.com/2016/01/06/renewables-and-grid-reliability/
2)Wind and solar are intermittent resources and their availability/output often does not match or support system needs. While there is hope for battery technology, current goals are modest. Other resources must compensate for the intermittency of wind and solar. The greater the percentage of wind and solar the greater the challenge and cost for backup. Previous writings on this topic include:
3) The success of wind and solar installations is highly location specific. You can pull up maps showing the suitability and appropriateness of various locations for both wind and solar power. Other land use considerations make locations more or less suitable for wind and solar as well. Current effort to increase wind and solar make use of the most optimal sites. Remaining sites are less optimal. As penetration levels increase above current levels the suitability of potential sites will decrease. The posting below cowritten with Rud Istavan provides some discussion of locational problems.
4) Wind and solar depend on materials which must be mined and their ability may be limited. Greatly increasing solar and wind production will likely increase costs and create supply problems. European wind power is already seeing a fight over scarce materials.
5)As wind and solar generation increase penetration it will become more and more challenging for other resources to subsidize their expansion. It’s one thing to subsidize a small component of the generation mix, another thing entirely to subsidize the major components.
6)It takes a lot of energy to build wind and solar facilities. Their operation and support consume a lot of energy. Many see that it is doubtful that such facilities can support themselves, serve load and provide enough energy to build replacement facilities of the same sort. Additionally, if electric vehicles are thrown in, the problem is further magnified. The “green” plan to eliminate gas appliances and added losses from increased battery deployment will not help either. There are a class of concerns focusing on all the energy and resources consumed by wind and solar resources. This is referred to as the energy density or power density problem. Here are a couple links (here, here, here and here) discussing these type concerns. These concerns have been outside my area of experience. I hope that readers may add more references in the comments.
7)Wind and solar make the study, control and operation of the power system more complicated and uncertain. These resources are intermittent and more unpredictable for operators to contend with. To maintain stability good modeling is imperative. Detailed models are run involving complex differential equations. Planners can force builders of large power plants to provide pretty good data on the plant impacts. Getting good data for dispersed projects with many small elements which might change during a project and after installation is much more challenging. Lastly, system operators and planners have years of experience with large rotating machines, not as much with wind and solar.
8)Widespread deployment of wind and solar would require that power be transmitted across great distances (or you would need an unrealistic and incredible amount of battery storage.) Getting wind’s power from the plains to the population centers involves long transmission lines. Green advocates argue that imbalances between load and generation from solar and wind resources can be overcome by drawing on resources from a broader geographical area. This requires even greater needs for long power lines and a robust grid. Wind and solar produce DC power which must be converted, with the help of the grid, to AC power. Edison and Tesla had a battle years ago over AC and DC power. Tesla won because to transmit power a long distance you need to use an alternating current system. As noted in item 1, solar and wind do not provide sufficient elements like inertia and vars for such a system to remain stable. (Side note-A high voltage DC line can transmit power great distances with lower losses. However, to utilize a high voltage DC line it is imperative to have a strong AC system receiving the power. The system must be robust such that the power can be converted from DC to AC. High voltage DC lines will not be the savior of a wind and solar based system.) While high levels of wind and solar penetration require a robust grid, their greater presence reduces the capability of the grid.
The above is a formidable list of challenges. How might they be overcome? Not by economies of scale from increased wind and solar production. First off, it’s hard to imagine that any economies of scale would allow these resources to leap the formidable challenges described above. Secondly, it does not appear that significant improvements in economies of scale are to be expected. My perusal of the topic shows that attempts to find economies of scale have all failed. Building more and more smaller units likely will not provide greater economies of scale due to increased material costs. Larger wind and solar facilities incur a class of costs not seen by smaller facilities. Promoters of wind and solar argue instead that smaller local projects provide more benefits than might be obtained from larger facilities.
Could nuclear energy be a piece of a lower carbon emission future? Most certainly. None of the above concerns apply to nuclear power. We could see cheaper costs from standardized nuclear facilities and reasonable regulations. Hydro too works well with the power system. Unfortunately, there are negligible to no potential locations to expand hydro generation. (Note-pumped storage is an option for storing energy, but not producing additional net energy).
It is way too soon to be envisioning a 100% renewable future with significant contributions from current wind and solar capabilities. It is not a good strategy to support current “green” technologies and retire and prohibit conventional generation hoping that a miracle will occur when we need it. Perhaps with the extensive deployment of nuclear power, carbon capture and other technologies we might be able to approach a zero-carbon grid. At best, current wind and solar technologies will play at most a small part in such a plan.
This is the first post in a series on The Penetration Problem
Part 1 Wind and Solar: The More You Do, The Harder it Gets
Part 2 Will the Inflation Reduction Act Cause a Blackout?
via Climate Etc.