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Energy Systems Categorized

Sandy Lawrence's picture
retired MD I write and lecture on energy, climate, grid, and epidemiology

I post almost daily on science topics, dealing with energy systems, the climate system, the electric grid and epidemiology. Background is in academic medicine, but I have also been teaching in...

  • Member since 2021
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  • Dec 31, 2021

I have been using the following outline to lecture + write about energy, including in a book manuscript. Would welcome any + all suggestions on modification or expansion. Thanks.

Non-Animate Energy Systems Categorized

Energy efficiency + demand flexibility faster, easier, cheaper: 

negawatts + flexiwatts + negabarrels

Current solar energy [almost] all sustainable energy types: biofuels,

hydropower, wave power, ocean thermal energy conversion [OTEC],

photovoltaic, concentrating solar, wind

Ancient solar energy consists of fossil fuels: coal, natural gas, 

conventional oil, bitumen oil, kerogen oil

Nuclear fission possible due ancient type II supernovae producing

Th-90 + U-92 + Pu-94 [basis of fuel cycles]

Geothermal energy originates from compressive accretional

formation of planet, coupled with extensive suite of 

radioactive substances decaying over eons

Tidal energy derives at root solely from gravitational interactions 

between Sun + Earth + Moon 

Piezoelectric + thermoelectric + thermomagnetic + triboelectric

generation niche technologies from materials science

Hydrogen [fuel cells] + electricity [secondary forms of energy]


Nathan Wilson's picture
Nathan Wilson on Jan 2, 2022

Sandy, you've listed lots of good topics, but the way it is organized will determine how hard it will be for your audience to draw useful conclusions.


The list hints at the difference between primary energy sources (i.e. renewables, nuclear, fossil fuel) and energy carriers (i.e. electricity, hydrogen, hydrocarbons; need to add batteries, hot water for district heat, and ammonia as fertilizer and fuel).  They should be two separate lists. Of course, the efficiency/negawatts discussion is applicable to all energy sources, so should also be treated separately.


The list needs evaluation criteria:  

- Environmental impact: Fossil and bio fuels necessarily involve air pollution.  Utilization of dilute energy sources like renewables will necessarily involve a large environmental footprint.  Fossil involves release of stored CO2.  Renewables and batteries necessarily involve use of mined resources and disposal of waste.  Nuclear technologies involve use of mined resources and disposal of waste as well, but the enormous energy density means much less of both is needed.

- Dispatchability: all non-dispatchable technologies are inherently dependent on other energy technologies for viability (i.e. fossil fuel backup/supplement, hydro supplement, or storage).

- Portability/storability: how to get the energy to where it is needed? Some energy sources are also carriers (fossil & nuclear).  Electricity is the most versatile, but is expensive to store or convert.  Hydrogen is expensive and somewhat versatile.  Ammonia is a heavily used/transported specialty commodity.  Hot water can couple to very cheap low grade waste heat, but is not good for transportation distances of over a few dozen miles.  Nuclear is the only source that works for multi-decade storage quantities.

- Economic timing: renewables and nuclear expenditures are primarily up-front capital costs, but with fossil fuel, the user cost is primarily fuel (and external/environmental/health costs), which are paid over time or deferred, not paid up-front.  This difference is very important for developing nations.


Lastly, nuclear fusion needs to be part of the discussion, as it is arguably not much farther from widespread use as many of the renewable technologies, and it can have a profound effect on the discussion.  Nuclear fission with breeder reactors and solar are obviously both inexhaustible at our current energy usage rates, and the fission breeder will allow us to increase our energy usage with low environmental impact.  But fusion will have even lower environmental impact and suggests the shocking question: why conserve?

All economic activity has an environmental impact, but buying energy services via fusion may have the least impact.  It is a very benign way of spending the vast wealth that we enjoy in developed countries.  We need not contemplate giving up air-travel or even space travel in a future built around fusion.

Sandy Lawrence's picture
Sandy Lawrence on Jan 3, 2022

Nathan, wonderful explication on my purposely sparse outline of the categories of energy now available to civilization. The actual book manuscript spends 450 pp placing a whole lot of detail on this scaffolding. Couple of responses may be of interest:
Batteries not a primary source of energy, only a store, likewise thermal storage in the form of either heat or cold. Fusion I explicitly excluded since not yet commercially proven, though I share your opinion that we are getting closer: no longer the 'fusion has always been 20 yrs away' meme. Ammonia is indeed a specialty chemical + energy carrier but not a primary source of energy. Nuclear may have multi-decade storage of molecules such as UO3, but renewables such as solar + wind cannot be stored, rather are ubiquitously available + replenishable. Not only non-dispatchable energy technologies are 'inherently dependent on other energy technologies for viability,' but rather all energy sources are. The grid from its inception was designed to have multiple interdependent sources of generation, because no technology has a capacity factor of 100%. And generators drop out of the system in both planned + scheduled as well as unplanned + very awkward scenarios. Efficient use of energy as discussed by Amory Lovins + others is always faster, cheaper, easier + often permanent. The optimal smart grid will use demand modulation, energy efficiency, wind, solar, geothermal, wave, tidal + other fluxes of energy. Cybersecurity is important. Islanding capability is important. Democratization of the fourth level of the electric grid, with information + electricity exchanged bidirectionally between distribution utilities + residentail/commercial/industrial users will be our future. Clearly net decarbonization is both feasible + necessary. I think complete denucleariation of the grid is possible + actually underway. At one point the U.S. had 123 or 124 commercial electricity-generation reactors. But we are down to 93 + headed further down. Look at the 2 Summer reactors canceled in South Carolina + the money pit of the Vogtle reactors in Georgia, yrs behind scheduled + cost projections essentially doubled to $28.5 billion for 2 reactors just announced last yr. Nuclear alone I sense would be a very protracted discussion.
I personally am looking forward to my first flight on an electric airplane. We live south of Vancouver, BC, + a company Harbour Air is testing float planes; I am on their wait list for a flight. Battery-powered planes are on the drawing board, + eminently likely to be ramped up to at least a 1,000 mile range, which could be used to eliminate about 30% of the fossil fuel flights globally.
I have already saved your many cogent suggestions + really appreciate the thought + effort you put into this. Obviously you + a lot of other members of the Energy Collective Group have put a lot of years of education + thought into this work, whereas I am a Johnny-come-lately in contrast, with my background in medicine.

Nathan Wilson's picture
Nathan Wilson on Jan 4, 2022


Air-transport is much more dependent on energy storage density than personal cars, because the distances involved are much higher, the weight sensitivity greater, and the energy use per passenger-mile is somewhat worse.  We are seeing a few applications for battery powered airplanes today which involve travelling less than a few dozen miles (i.e. less even than a typical car): flight training, especially take-offs/landings and self-launched motor-gliders.  The range limitation comes from the weight of the batteries.  It would be great if batteries improved ten-fold; but why do you think this will happen?  We have already changed from using lead to nickel to lithium, the lightest metal; we may well see future improvements in cost effectiveness, but energy/mass ratio improvements will likely slow to a stop.


"I think complete denuclearization of the grid is possible + actually underway."

Of course the grid worked fine before nuclear (except that the resulting air pollution substantially shortened the lives of the people it served and increased the CO2 in the environment).  Returning to that would be a tragedy. 

The claims by anti-nuclear activists that it would somehow make us safer are based on emotions & ideology, rather than science (the actual science says nuclear is the safest source of energy).   

The claims that renewables can do the same job are untrue as well; the variability of solar and wind increase the benefit of using fossil gas to the point that fossil fuel gets locked in (once the renewable penetration exceeds the capacity factor).  The dilute nature of sunlight and wind mean that renewables will increase humanity's environmental footprint.

Decades into the renewables era, there are zero grids which have deeply decarbonized using solar & wind, but France, Sweden, and Switzerland have all deeply decarbonized using nuclear+hydro (by grid, I mean the whole "balancing area", so small towns that export huge amounts of windpower for hours at a time, then import a little coal power when the wind stops don't count; it's the whole grid that matters). 

As to nuclear costs: the amount of concrete and steel involved is much less than for renewables for the same energy production, so there is plenty of opportunity for improvement.


"... nuclear ... a very protracted discussion." Yep, scientific discussions are much simpler than ideological ones.  But Ideological discussions matter too.

Sandy Lawrence's picture
Sandy Lawrence on Jan 4, 2022

Nathan, nuclear safety is not even my primary argument. Given the multiple subsidies that nuclear has had for going on 65 yrs, why is it still so expensive? The way the grid works, generators must bid in at 10am for the next 24 hrs, which the grid manager [independent system operator or equivalent] accepts bids for about 90% of that day. Separaate auctions at 1 hr, often even increments as short as 5 minutes occasionally. The problem with nuclear is simply that it cannot compete on a level playing field [especially when you look at Lazard's LCOE analyses. 
SMR reactors will take more than a decade to ramp up to scaled deployment, + their development steals development support + money for the renewables that continue to follow virtuous cost curves. 
Please speak to the failures of the Summer + Vogtle reactors. And offer an explanation for why we are down to 93 commercial plants in the U.S. It is not due to citizen opposition. It is a economic failure of this industry segment. I continue to express my appreciation for your input here.

Nathan Wilson's picture
Nathan Wilson on Jan 6, 2022

Sandy, you can't measure the torque on a screw unless that screw is turning; similarly, you can't measure the volume cost of something if that something is not in volume production.  Any complex item is going to be expensive the first few times you try to build it; that is equally true of windpower, solar, airplanes, rockets, or nuclear reactors. 


To make predictions of how low nuclear costs could go in the future, we should use the normal construction industry practice of basing the estimate on the amount of concrete and steel required.  For large nuclear plants, that's around an order of magnitude less than is required for renewables, for the plant's lifetime energy output.


SMRs are promising in that we'll move down the learning curve faster, since we'll build more units per GWatt of capacity built.  However, I would note that to decarbonize our US grid in a timely fashion, we need to add clean electric generation at a rate over 20 GWatt_avg per year; that is plenty fast enough to drive costs down in even large reactors such as the AP-1000.  In fact, China is building their nuclear fleet primarily around 1-1.4 GW reactors, even though they are also developing a smaller reactor for export; the bigger units use less material and cost less per unit energy produced.


One may think that because America has built 100 GWatt's of nuclear reactors in the past, we should already know how to do it well.  It's easy for an inactive industry to forget that sort of thing, particularly after having gone through a period during which making the product _more_ expensive was the most profitable approach (locked-in contracts, dim prospects for future projects, cost-plus contracts, government regulators who help restrict competition, etc).


As to why existing nuclear plants are being closed down:  

- Overly rigid government regulations, lack of competition, and excessive fear of accidents and radiation releases block operating cost reductions.

- Utilities and the fossil fuel industry benefit from closing nuclear plants because reduced supply causes wholesale prices to go up (bad for consumers, good for producers).


Why should we make the investment to bring the industry back in the face of seemingly less expensive competition?  For the same reason given by advocates of renewables 20 years ago: the superficially cheap fossil fuel competition is not paying for their external costs (pollution, CO2 emissions, and oil wars); that's not a level playing field.  Also one new reason: variable renewables are unlikely to free us from dependence on fossil fuel because they make only variable electricity, but what customers want is electricity-on-demand, which comes only from grids which are dominated by dispatchable generation.

Sandy Lawrence's picture
Sandy Lawrence on Jan 6, 2022

I would comment here that the 2 canceled Summer reactors + the 2 Vogtle reactors are AP1000 Generation III+ reactors.  I am still looking for an explanation of their failures.
Also, your point that U.S. nuclear plants 'are being closed down...[from lack of competition], which is strictly counter-intuitive for 2 reasons. First, any technology not facing a competitor should thrive. Second, in the current U.S. grids the vertically integrated old structure is being progressively disaggregated, so nukes have to bid in competitively. This is why they are failing economically.
Let me refer you to the most recent Lazardian LCOE graphic analysis which I will post later.
Finally, would you be interested in being put on my GoogleDoc, specifically the chapter on nuclear power? You would be a great, critically-thinking honest reviewer, which I would love.

Nathan Wilson's picture
Nathan Wilson on Jan 8, 2022

Regarding the US AP1000 reactors: these were first-of-a-kind projects, so problems were inevitable.  Making things worse, they were built by people and companies with no recent experience building reactors.


You've pulled the "lack of competition" item out of context.  In a tightly regulated industry, there is a lot of insulation between the competition and the teams doing the work.  The teams can't change suppliers easily, because their suppliers and the products have to be certified by regulators, which takes time and money.  The plant designers can't push through cost reductions initiatives, again because regulations make all changes more painful, and doing nothing is the path of least resistance.


I am willing to look at your GoogleDoc, but I can't promise how much time I'll have available to spend on it.

Sandy Lawrence's picture
Thank Sandy for the Post!
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