Sunday, March 5, 2017

Dr Charles Hall is still totally wrong about EROI

Recently I saw an article on and found that Dr Charles Hall is still making the same incorrect claims. Once again, Dr Hall is claiming that civilization requires an EROI higher than a certain amount to feed its population and support advanced activities. Apparently, if EROI drops below a certain level, then civilization will revert to a primitive state. It could even result in mass starvation if EROI drops too low.

The following remarks are taken from the article:

[Summarizing his research] Pretty soon it looked like we needed an EROI of at least 10:1 to take care of the minimum requirements of society, and maybe 15:1 (numbers are very approximate) for a modern civilization.

Similar ideas are expressed in his earlier papers, such as Hall's "energy pyramid"[1] in Lambert & Hall[2].

Apparently, we require an EROI of at least 5:1 just to grow enough food to survive, whereas we require an EROI of at least 15:1 to have a modern, industrialized society, according to Dr. Hall and associates.

However, those numbers are clearly wrong. A decline in EROI from 15 to 5 implies a decline in net energy of only ~14%, and this can be shown using arithmetic ( (1-1/5)/(1-1/15) = ~86%). As a more extreme example, a decline in EROI from 1 billion down to 5 implies a decline in net energy of less than 20% (19.999...). Such declines in EROI imply only modest losses of net energy, and do not imply the collapse of civilization, mass starvation, or a return to a medieval mode of life. Above a very low level, EROI makes practically no difference; for example, a decrease in EROI from 1 trillion down to 10 implies a loss of less than 10% of net energy.

Presumably, the error here is to infer that modern civilization must have a proportionally higher EROI than primitive civilization, in order to gain more net energy to support more advanced activities. Dr Hall observes that the kung (a hunter-gatherer tribe) has an EROI of approximately 10. Presumably, Dr Hall infers that modern civilization must have a higher EROI to obtain more net energy.

From the article:
Lee's assessment of the traditional kung hunter gatherer life style implies an EROI of 10:1 and lots of leisure (except during droughts–which is the bottleneck).

However, Hall's inference is incorrect. Modern civilization doesn't just have a higher EROI than primitive societies; it also has a greater AMOUNT of gross energy which it can obtain. Primitive societies have too little energy they obtain, regardless of EROI. Even if the kung increased their EROI from 10 to 1 billion, it would result in less than 10% additional net energy, which presumably would make little difference. The problem is amount, not EROI. It is not possible to know how much net energy will be obtained from EROI alone.

The amount of net energy can be calculated using the following formula:

net = gross - gross/eroi

You will notice that it's not possible to solve the simple equation above using EROI alone. As a result, any remarks along the lines of "we require an EROI of at least x to have modern civilization" are incorrect. Without knowing how much GROSS energy is obtained, we cannot calculate how much NET energy will be obtained. Modern civilization runs on net energy, not a high EROI, so an EROI number by itself (without any indication of gross energy) provides no important information, unless the EROI ratio is lower than 1.

At present, the United States uses 6916 kg of oil equivalent capita, per year. Even if the average EROI ratio for the entire country dropped down to 3, the US would still have more net energy per capita than France[3]. The French are obviously capable of growing food, having education, and so on.

Dr. Hall then claims that we require an EROI of at least 3 to support modern transportation:

We found you needed to extract 3 liters at the well head to use 1 liter in the gas tank to drive the truck, i.e. an EROI of 3:1 was needed... But even this did not include the energy to put something in the truck (say grow some grain)

That claim is incorrect. Hall's paper in question[4] includes depreciation of all vehicles as an energy cost. It also includes all road construction. However, most vehicle depreciation occurs in personal vehicles which are used for discretionary trips. As a result, an EROI of 3 is not the minimum which civilization must have to deliver food in trucks, because civilization could curtail personal vehicles while retaining food delivery in trucks. Furthermore, the replacement rate of personal vehicles would decline proportionally as the rate of net energy to drive them declined. In other words, vehicle depreciation is not constant. As a result, the minimum EROI needed for modern transportation would be far lower than 3 because most of that energy investment could be curtailed without (thereby reducing the minimum EROI figure) without sacrificing anything essential.

It's not necessary for civilization to construct the entire first world edifice of cars and freeways before commencing any other activities. As a result, Hall's energy pyramid is incorrect, because the numbers contained in it would change as EROI declined, and also because those activities are not stacked on top of each other in the way implied by that diagram.

Dr. Hall then turns his attention to the idea of chaining energy sources. You could "chain" power plants (or "stack" them) and thereby achieve a higher aggregate EROI (This is discussed further on this blog, here). For example, if you had solar PV plant with an EROI of 2, you could use the output of that plant to build twice as many new ones, which would yield 4 units of energy for an initial investment of 1. Alternatively you could use the output from the initial plant to build 1.5 times as many new ones (which would yield 3 units of energy for an initial investment of 1) and then return the remaining net energy to society.

Dr. Hall addresses that issue in the same thread, as follows:

The problem with the "stacked" idea is that if you do that you do not deliver energy to society with the first (or second or third) investment — it all has to go to the "food chain" with only the final delivering energy to society.  So stack two EROI 2:1 technologies and you get 4:2, or the same ratio when you are done.

That is clearly incorrect. It is not necessary to devote the entire amount of gross energy obtained to building more solar panels. It would be possible to invest more than is required to replace existing solar panels, but less than the entire amount. This would still lead to exponential growth in net energy obtained (with any EROI higher than 1) while also providing energy for other purposes in the mean time. Exponential growth in energy supply would obviously allow us to obtain any amount until some limit (other than EROI) is reached. As a result, EROI is not proportional to net energy obtained by society.

Dr Hall also claims that solar PV with an EROI of 8 may not actually provide any net energy to society after including more factors as energy investments:

If the EROI [of solar] is 8:1 ... then it seems like you could make your society work. But let’s look closer. If you add in security systems, roads, and financial services and the EROI drops to 3:1 then it seems more problematic. But if you add in labor (i.e. the energy it takes to make the food, housing etc that labor buys with its salaries, calculated from national mean energy intensities times salaries for all necessary workers) it might drop to 1:1. Now what this means is that the energy from the PV system will support all the purchases of the workers that are building/maintaining the PV system, let’s say 10% will be taken care of, BUT THERE WILL BE NO PRODUCTION OF GOODS AND SERVICES for the rest of the population.

Of course, that implies that 7/8ths of the output of a modern power plant is devoted to the employees who work there and miscellaneous expenses like security cameras, roads to the plant, and so on. On its face, that number is highly implausible.  A modern solar PV power plant often has more than 250 MW nameplate capacity, which is equivalent to 47.5 MW continuously at a capacity factor of 0.19. Even if there were 2,000 employees who worked at the plant continuously for 30 years (which is false; solar plants have only a handful of employees), that would still imply more than 23.75 kw continuously per employee which is vastly higher than the total energy usage per capita of any industrialized country. That figure of energy usage includes the employees' discretionary consumption (such as taking plane trips to the Bahamas for vacation) which is not an energy investment.

There is another serious problem with Dr. Hall's ideas on this matter. Over and over again, Dr. Hall treats energy returns as energy investments. In doing so, he places terms in the denominator of the EROI fraction which belong in the numerator. For example, in his paper What is the minimum EROI that society must have?[4], he treats all personal vehicle depreciation as an energy investment. However, most personal vehicle travel is for discretionary trips and not for activities such as (say) gathering coal. As a result, such vehicle travel represents an energy return, not an investment. As another example, Hall repeatedly treats first world salaries for certain workers as energy investments; for example, in the remarks above, or in his book Spain's Photovoltaic Revolution[8], he treats salaries of power plant employees as energy investments.

If we treat things like first world salaries, discretionary car travel, vacations, etc as energy investments, then it would be possible to increase EROI greatly, by simply curtailing discretionary first-world activities somewhat for power plant employees. As a result, the EROI of those sources of energy would increase greatly as salaries declined, in which case, Hall's EROI figures would no longer hold. This implies that Hall's warnings about the decline of industrial civilization wouldn't hold either, because any decline in the first world incomes of power plant employees would cause a concomitant large increase in the EROI of power plants.

In conclusion. Dr. Hall's ideas and papers contain serious mathematical and logical errors which invalidate his analysis. He assumes that modern civilization must have a proportionally higher EROI than primitive civilization in order to obtain more net energy to support advanced activities. However, that assumption is clearly wrong, because modern civilization also has more gross energy than primitive civilization, and so would obtain vastly more net energy even with far lower EROI ratios. Furthermore, Dr Hall is throwing around numbers which are clearly implausible and which are refuted using straightforward arithmetic. What's more, Dr. Hall's criticism of the "stacked" energy source idea is incorrect, insofar as he wrongly assumes that society must devote either all of leftover energy, or none, to obtaining more energy. Finally, Dr. Hall repeatedly treats energy returns as investments, and in so doing, invalidates his other conclusions.

There is one more thing I should point out. These ideas are not new. Dr. Hall and his mentor (HT Odum) have issued warnings about declining net energy and imminent grim consequences to civilization, over and over again, since the early 1970s. Odum first warned in the early 1970s that all sources of energy then had perilously low and declining EROI (called "energy yield ratio" back then) [5]. Odum claimed repeatedly during the 1970s that nuclear reactors probably would not yield more energy over their lifetimes than was required to construct them and refine the Uranium. Odum also claimed at that time that the EROI of coal fired electricity was extremely low and declining. Dr Hall started warning in the early 1980s (during the oil crisis) that the EROI of oil was disastrously low and could decline to just above 1 fairly soon thereafter[6].  Dr Hall warned again, in 2009, that the EROI of oil and gas was perilously declining: "The fact that the EROI for global oil and gas extraction declined by nearly half from 1999 to 2006 is cause for concern."[7] Both Hall and Odum devoted much of their professional careers to issuing such warnings about almost all sources of energy, over many decades. These most recent warnings about the EROI of renewables are simply repetitions of earlier, failed predictions and warnings, applied to other sources of energy back then. Dr. Hall needs to explain why these ideas and methods have failed so badly in their predictions in the past, when applied to fossil fuels, but are still correct now when applied to renewables.

I have pointed out repeatedly, for several years, that Dr Hall's analysis contains mathematical errors. Dr Hall responds to this by being petulant and insulting:

First I would like to say that the bountiful energy blog post is embarrassingly poor science and totally unacceptable. As one point the author does not back his (often erroneous) statements with references. The importance of peer review is obvious from this non peer-reviewed post.

However, that simply does not address the mathematical errors I have pointed out.

If Dr Hall offers no relevant response to these objections, then his ideas are refuted.




[3] . The USA has an energy use per capita of 6916 kg of oil equivalent, which is 4613 net energy per capita with an EROI of 3. France has an energy use per capita of 3840 kg of oil per capita, which implies lower net energy per capita regardless of the EROI of France.

[4] What is the minimum EROI that society must have?, pp 42, table 2. Charles A. S. Hall, Stephen Balogh and David J. R. Murphy. Energies 2009, 2, 25-47.

[5] Energy Basis for Man and Nature. Howard T Odum and Elisabeth C Odum. MacGraw Hill, 1974.

[6] Petroleum Drilling and Production in the United States: Yield per Effort and Net Energy Analysis. Charles A.S. Hall, Cutler Cleveland. Science, 211, 4482, 576-579.

[7] A Preliminary Investigation of Energy Return on Energy Investment for Global Oil and Gas Production. Nathan Gagnon, Charles A.S. Hall, and Lysle Brinker

[8] Spain's Photovoltaic Revolution. Pedro A. Prieto and Charles A.S. Hall. Springer, 2013.

Sunday, July 17, 2016

The Energy Trap

In this post I will address the issue called the "Energy Trap", which was explained well by Tom Murphy on his excellent blog post and re-iterated by oatleg in the comments to my prior post. Basically, the "energy trap" is a scenario where fossil fuels peak and start to decline, and we must start investing energy in building renewables in order to replace fossil fuels. But there is a problem, as follows: renewables require a large up-front investment of energy, but pay back that energy only gradually over many years. As a result, when fossil fuels start to decline, we must make large up-front investments in renewable power precisely when energy for investment is in short supply, leading to a temporary "energy deficit". For a fuller description of this phenomenon, I highly recommend reading Tom Murphy's blog post entitled The Energy Trap.

I decided to model this phenomenon of the "energy trap" by using a small computer program, which I wrote in python. Any reader can download the python interpreter for free and run the simulation on his computer (the source code is posted in the comments below).

For the simulation, I made the following assumptions:
  1. Civilization gets all of its energy as electricity, generated from burning fossil fuels
  2. All fossil fuels peak on the same day and decline immediately according to the right-hand side of a Gaussian curve
  3. Fossil fuels start declining immediately without warning, and without any kind of production plateau
  4. The Gaussian decline curve has a standard deviation of 30 years which is a very rapid decline. As a result, there is a 50% decline in all fossil fuel production in only 34 years.
  5. There are no "unconventional" fossil fuels which will allow us to delay the decline or extend the decline curve
  6. No preparation has been made. The investment in renewables beforehand was zero.
  7. Investors and decision-makers do not begin investing in renewables until 7 years after the declines in fossil fuel production have begun, because it takes time to realize what is happening and ramp up PV production.
  8. Investors use a very naive formula for determining how much PV to build. Once they realize what is happening, they start investing about 5% of electricity production per year to building renewables, later increasing the investment to 1/ERoEI.
Please note that these assumptions are all incredibly pessimistic. These were by far the most pessimistic assumptions which I could imagine but which were still at least somewhat plausible.

If I run my simulation with those parameters, what results do I get? Here are the results in tabular format:
(Note: All values are fractions of the original gross amount of energy from fossil fuels; so an invest_pv column of 0.05 means that 5% of the original gross amount of energy is invested in PV panels)

As we can see, there is an "energy deficit" starting on year 8, because of the energy trap. At that point, civilization is only consuming 93.88% as much electricity as it used to. The reason is because year 8 is when investors have realized that fossil fuels are on a permanent decline, and start "investing" only 5% of yearly electricity in building solar panels. However, the 5% investment is all up front, with little payout this year, leading to an energy deficit of 5% this year plus a few more percent for the amount that fossil fuels had declined thus far. The energy deficit is brief, and civilization is back up to 97% consumption in 4 years.

Which raises the question: what will we actually do? Will we decide to forgo 5% of our electricity consumption now, as I assume above, in order to avert the gradual collapse of civilization over the next few decades? Or will we take the short-term view, and decide to "eat our seed corn" (so to speak) and cannibalize our energy infrastructure, leading to a small increase in our energy consumption now but the destruction of our civilization later?

Tom Murphy has this to say about it:

"Politically, the Energy Trap is a killer. In my lifetime, I have not witnessed in our political system the adult behavior that would be needed to buckle down for a long-term goal involving short-term sacrifice."

I disagree with that remark. These decisions are not made by our political system, but by investors in energy markets. Those investors routinely make short term sacrifices for larger payouts later. That is what investment means. For example, investors routinely carry out long-term planning and buy capital equipment (such as power plants) which will pay out over 30 years, but which require an up-front investment now. That is why we have power plants. Investors could always eat their seed corn and spend the money now rather than investing in the future. In general, they don't do that.

When fossil fuels start declining, the price of energy will skyrocket. Even a modest decline of a few percent of energy, could lead to a tripling of prices or more. At that point, the financial return of investing in renewables would be enormous and nearly certain. Any investment in renewables would promise vast payouts down the line, far higher than are obtained by any other investments. As a result, investors will transfer money from other investments in to this one. Investors are capable of outbidding consumers for that 5% of yearly electricity which is necessary to invest for the transition.

The energy trap is actually a fairly mild problem. Even using the incredibly pessimistic assumptions I outlined above, we will never face more than a 6.12% deficit of energy. The deficit starts decreasing right away and almost vanishes within 9 years after it begun. The energy trap is easy to overcome, with only modest and temporary sacrifices.

Furthermore, the deficit of 6.12% is almost certainly higher than what we will face in reality. We have begun transitioning to renewables decades before fossil fuels have begun declining. Furthermore, we get a large fraction of our energy now from sources other than fossil fuels (like nuclear and hydro-electric). What's more, the decline in fossil fuel production will be far more gradual than I modeled above. Also, there will be a production plateau lasting decades before fossil fuels start declining. Furthermore, investors will use a more sophisticated algorithm when determining how much PV to build, rather than just suddenly increasing PV investment from 0% to 5% (as I modeled above) which briefly worsens the energy deficit. When I run my model with more realistic assumptions that aren't so incredibly pessimistic, I find an energy deficit of less than 0.4% at its worst point.

In conclusion, the energy trap is easy to overcome with only modest adjustments. It requires modest planning--the kind which investment markets routinely carry out. As a result, the energy trap will be a minor problem which will impose only temporary and insignificant reductions in energy, in my opinion. It is also possible that civilization will transition to renewables before we reach peak fossil fuels, in which case the energy deficit will be zero.

(NOTE: The python source code is posted in the comments below)
(NOTE: I made minor changes to the wording of this article two days after initial publication. The values from the table have not changed.)

Sunday, June 19, 2016

ERoEI is unimportant and is being used incorrectly

In this article I will show that ERoEI is unimportant by itself. It usually does not matter if ERoEI is increasing or decreasing. ERoEI provides no guidance about which sources of energy we should pursue, nor does it offer any guidance about how much net energy will be available to us in the future. By itself, ERoEI is a useless figure, unless it is lower than 1, which it almost never is. Although different sources of energy (such as coal or solar PV) have different ERoEI ratios, this means nothing important.

What is important to civilization (and to us) is the amount of net energy obtained from a source of energy. It is an amount of net energy (not a high ERoEI) which allows us to drive cars, fly airplanes, and so on. If we obtain 1 GWh of NET energy, then it does not matter if it came from a high-ERoEI source, or from a low one. What matters is the amount of net energy.

In turn, the amount of net energy depends upon two things: ERoEI AND the amount of gross energy. BOTH of those figures are required to determine the amount of net energy obtained. ERoEI by itself tells us almost nothing.

Let me provide an example, to demonstrate this point. Suppose you have a solar PV panel with an ERoEI of 3, which returns 1KW on average continuously for 30 years. In that case, the net energy provided by that solar panel is 175.2 MWh ((1*24*365*30)*(1-1/3)) over its lifetime. If, however you have ten such solar panels, then the net energy returned is ten times higher (1752 MWh), despite no change in ERoEI.

For the most part, the amount of NET energy we can obtain is determined by the amount of GROSS energy we can obtain, not by ERoEI. Usually, ERoEI is only a minor factor. This is because the difference in the amount of gross energy between sources of energy is so large that it completely overshadows any minor influence that ERoEI would have.

For example, suppose we had single 1KW solar panel, and the panel had a very low ERoEI of 4 (which is certainly an underestimate [1]). Even if you increased the ERoEI from the very low value of 4, all the way up to to infinity, so that no energy was required to replace that solar panel, it would make little difference--it would increase the amount of NET energy obtained by only 25%. On the other hand, if you could build 3 such solar panels, instead of 1, then you would triple the net energy obtained. In this case, building two more solar panels had 12x greater effect than increasing the ERoEI to infinity.

For the most part, the net energy obtained from solar power would be determined by the number of solar panels built, not by their ERoEI. In turn, the number of solar panels which can be built, is determined by non-energy factors like capital and labor, because those are the scarce factors which prevent the construction of more solar panels. Energy for investment is not scarce, because this planet is bombarded with 23,000 terawatt-years/year of solar radiation, which is vastly more than we will ever use. It is the scarce factors which determine how many solar panels we can build, and therefore, for the most part, how much net energy we will obtain. This point is complicated and requires further elaboration, so I will discuss it in a subsequent article. Suffice it to say, that the net energy of solar power is determined by non-energy factors such as capital and labor, and has almost no relation to ERoEI, because capital and labor (not energy) are the scarce factors which prevent the construction of more solar panels.

Generally speaking, the amount of net energy goes up as ERoEI declines, although it’s a weak correlation. This is because the amount of gross energy is vastly higher at lower ERoEI ratios, and the greater amount of gross energy more than compensates for any decline in ERoEI.

For example, solar PV could provide far more net energy than coal, regardless of its lower ERoEI. This is because solar radiation is so much more abundant that its lower ERoEI would be completely overshadowed by its greater amount. As a demonstration, suppose we could convert only 1% of solar radiation striking this planet into electricity using solar panels. In that case, we would obtain 40,000 times more electricity from solar power than we currently obtain from burning coal [2]. That figure does not take into account ERoEI, but it would make little difference. Even if solar PV had an extremely low ERoEI of 4 (certainly an underestimate), and coal had an ERoEI of infinity, it still would only reduce the maximum net energy of solar power by 25% relative to coal [3]. Since solar power is 40,000 times more abundant than coal, an ERoEI adjustment of 25% is not important. It would mean only that we could obtain 30,000 times more energy from solar power than from coal, rather than 40,000 times more [4].

Of course, if the ERoEI of some energy source were extremely low (like less than 2), then ERoEI would become an important factor. In that case, ERoEI would actually make a substantial difference, because it would cause a 50% or greater net energy loss. However, all common sources of generating electricity have ERoEI ratios far higher than that. With an ERoEI higher than 8 (which all sources of generating electricity have), the amount of energy spent obtaining more energy is only 12.5%, which is completely overshadowed by differences in gross amount between energy sources.

Again: net energy available is a function of BOTH EROEI AND AMOUNT. Either one of them by itself cannot be used to calculate net energy. If we wish to use a “rule of thumb”, then we should assume that MORE net energy is available at lower ERoEI ratios, but the correlation is so weak that it can’t be relied upon. In any case, ERoEI is not generally an important factor.

Unfortunately, ERoEI theorists do not realize any of this. Over and over again, they wrongly assume that ERoEI is somehow proportional to net energy. They assume that a higher ERoEI somehow implies more net energy obtained. This is a severe mathematical error, but it’s repeated endlessly throughout the ERoEI literature, across decades.

Let me provide some examples which I read just a few days ago:

“Look [at a] Cheetah… That beautiful and ultra efficient machine, needs an EROI of about 3:1... That’s a metabolic minimum EROI for mammals.Being the minimum EROI for any live being (mammals in particular) 2-3:1 in average, to be kept alive as species and for the couple to successfully breed their offspring (minimum of 2-3 per couple), probably Charles Hall is very right to state that a minimum EROI of 5:1 is required to have a minimum (very primitive and elemental) of civilization, beyond us living as naked apes.”
No, because that wrongly assumes that greater amounts of net energy are obtained at higher ERoEI. That is a basic mathematical error. Frequently, using a lower ERoEI source of energy will obtain more net energy than a higher ERoEI one.

The Cheetah example is also mistaken in other ways. The Cheetah doesn’t just have a low ERoEI; it also has TOO FEW prey which it can catch. If the Cheetah could eat prey every 5 minutes, then it would have a vast excess of energy even at an ERoEI of 1.5. The problem is that many animals eat only once per day and some animals (such as crocodiles) eat only once per week or so. The problem is amount, not ERoEI. If they eat only 10,000 kilocalories per week, then increasing the ERoEI wouldn’t matter much (even increasing ERoEI to infinity in this case would only gain the animal another 3,300 kilocalories). What would help is to catch MORE prey.

Here is another example of the same mistake:
We can take our ERoEI 20 FF and invest them in ERoEI 50 sources and make a huge energy profit. Or we can invest them in <5 and make a loss. Our policy makers have lost their heads electing to promote loss making activities.”

No, because that is confusing ERoEI with an AMOUNT of net energy. If an ERoEI were an amount, then spending fossil fuels with ERoEI 20 on solar panels with ERoEI 5, would imply a loss of 15. However, you cannot subtract the ERoEIs of different sources of energy, because they are not AMOUNTS which can subtracted. The correct mathematical operation is to multiply those two numbers, not subtract them.

If you take ERoEI 20 fossil fuels, and invest them in ERoEI 5 solar PV, then the aggregate ERoEI is 100 (invest 1 unit of fossil fuels initially, obtain 20 units of fossil fuels with ERoEI of 20 thereby, invest each of those 20 units in solar panels with ERoEI 5, then obtain 100 units at the end of it for an initial investment of 1).

Here is another example:
IMO, the only thing that could delay the bad impacts of declining high ERoEI FF is to introduce to the global energy mix an energy source that has higher ERoEI than the fuels they have to replace. Introducing low ERoEI energy sources simply makes things worse.”

No, because (again) that is confusing ERoEI with an AMOUNT of net energy. The “bad impacts” are caused by TOO LITTLE net energy, not a low ERoEI. Adding any source of energy with an ERoEI higher than 1 increases the total amount of net energy available. Only an ERoEI lower than 1 would make things worse. If the source of energy is cheaper per unit of net energy (as solar power actually is) then it is easier to obtain more net energy that way, regardless of its ERoEI.

…All three of the above quotations are taken from leading figures in the ERoEI literature, all published within the last few weeks. Granted, the ERoEI movement is a tiny fringe movement, but these people are among the leading figures of it. Over and over again, they wrongly assume that ERoEI and net energy are somehow proportional, and that higher ERoEI implies more net energy. That is a basic mathematical error. Frequently, the opposite is the case.

What matters is the AMOUNT of NET energy available to civilization, and that amount is far higher for renewables than for any other source, regardless of ERoEI.

* NOTE: In this article, I am using the term "ERoEI" to by synonymous with "EROI" and other spellings. I am referring to the amount of energy obtained for an investment of energy. If ERoEI for some energy source were extremely low (like lower than 3) then ERoEI would start to become more important, since we'd need to build significantly more power plants to generate the same net energy. Since all common sources of generating electricity have an ERoEI much higher than that, ERoEI is not important in any real-world scenario.

I revised this article on August 18, two months after its initial publication, to improve the flow of the text.

Wednesday, June 17, 2015

There are many alternatives to oil

One of the main ideas of the peak oil doom movement is that there are no possible alternatives to oil. Oil is apparently some magical irreplaceable substance with no known alternatives, and no way to find alternatives. For example, here is a recent post from a prominent peak oiler on

...It is highly unlikely we will discover a viable alternative to oil... We can't invent a new energy source to oil since that would violate the laws of thermodynamics. You can't make something out of thin air just by imagining it.

As usual, that idea is factually totally wrong.

There have always been many alternatives to oil, since the beginning of the oil age. For example, cars can use electricity from batteries (most major car companies have released, or are releasing, battery-electric cars). Trains and buses can use electricity from overhead wires; more than half of rail traffic worldwide now uses this. Ships can use steam turbines which can use anything that will burn as fuel, such as coal, peat, wood chips, oil shale, torrefied biomass, etc. Internal combustion engines can use natural gas--even gas from fracking or methane hydrates. For the few uses which really require a liquid combustible fuel, there are many synthetic liquid fuels such as anhydrous ammonia, dimethyl ether, and many others. Those synthetic liquid fuels can be manufactured using electricity from renewable sources and abundant elements. All of the aforementioned alternatives have been available for many decades, and everyone in the relevant industries knows about them.

The only reason we don't use those alternatives already is price. For example, battery-electric cars and synthetic fuels are only competitive when oil costs $120/bbl or so.

When oil production enters its gradual terminal decline, the price of oil will shoot up and stay there. The economy will then gradually transition to now-cheaper alternatives. There is vastly more time than is required for the economy to transition to those alternatives (we have at least a century), and the economy has already begun transitioning to them, far earlier than required (car companies started designing plug-in vehicles at least a decade before any declines in oil production).

This kind of transition is something the economy does all the time. Companies are always evaluating alternatives and switching between them. Take ships as an example: the shipbuilding industry started off using sail, then switched to reciprocating steam engines burning coal, then switched to steam turbines burning coal, then switch to steam turbines burning oil, then switched to diesel engines burning oil. There have already been four major transitions in ship propulsion. There are many, many alternatives for the fifth transition. As another example, electricity production switched from hydroelectric, to oil, to coal, to nuclear and back, and now is switching from coal to gas in the US, because gas is now cheaper.

This notion that "there are no alternatives to oil" is just factually totally wrong.

It is also possible to use oil far more efficiently. When oil begins its very gradual decline and prices shoot up, people can buy cars such as Priuses which get twice the mileage. Shipping companies are already ordering ships that are more than twice as fuel-efficient. Cargo traffic can be switched from truck to rail which is 4x more efficient. Those things by themselves would compensate for declines in oil production for many decades.

Don't expect anything exciting or dramatic to happen to transportation networks. Granted, the price of oil may swing around wildly (because of inelasticity of demand), and there are recessions caused by many things. However, the actual supply of oil changes gradually over decades. Oil production won't enter a sustained decline for at least another decade, and the decline will be very gradual thereafter. There is a lot of time, and there are many alternatives.

Thursday, May 21, 2015

Energy decline theory is pseudoscience

Here is a response I wrote on a forum:
I'm sorry, but there's just no science happening here. It's not sufficient to say the word "science" and to use scientific-sounding terms like "biophysical". Those kinds of things are also common within pseudoscience.

What is required are specific, falsifiable, risky predictions of things which weren't happening anyway. Then those predictions must be confirmed by subsequent evidence. That is the first step toward actual science, and it has never happened and is not happening within this group.

This group has all the hallmarks of pseudoscience. It has never produced any risky, falsifiable predictions which were confirmed by subsequent evidence, not even once. There have been massive failures of prediction, over and over again, but the theories remain totally unchanged, and the failures of prediction are not even addressed. Failures of prediction are handled by making the theory less and less falsifiable ("there is now a long descent which is difficult to see", see John Greer). Members do not respond to criticism, and leave errors uncorrected when they are pointed out. Notably, this group is ignored by legitimate researchers. There is almost no interconnection between this group and actual legitimate fields of study, and this material is rarely cited outside this group. Notably, it appears that this group settles its conclusions in advance ("civilization is about to collapse"), then generates theory after theory which all lead to that conclusion, but then the predictions all fail.

If you guys want to start doing science, then you need to respond to criticism without badly misreading it, modify your theories in light of failed predictions, and make falsifiable, risky predictions which are confirmed by subsequent evidence. Those things would be the first steps toward actual science, but those things are just not happening here.

Here is another post from the same thread:
George, you said:
"I'm talking about net free energy per capita, not raw energy produced... The numbers you quote do not take into account the amount of that energy it took to obtain that amount...So with slowing net energy increase and increasing total population the amount of usable energy for the economy per individual is in decline."

No, that's clearly wrong. Let's do the math. According to the EIA's numbers, world energy consumption has increased from 480x10^15 to 524x10^15 btu, between 2009 and 2013 (inclusive). At the same time, world population increased from 6.83x10^9 to 7.08x10^9 people ( That means that per-capita energy consumption has increased from 70.27x10^6 btu/capita to 74.01x10^6 btu/capita in that time. In other words, per capita energy consumption increased by 5.3% in 4 years, which is a compound growth rate of ~1.3% per year.

Now let's look at the prior 29 year period, from 1980-2009 (inclusive), using the same sources of data. Per capita energy consumption increased from 63.63x10^6 btu/capita to 70.27x10^6 btu/capita over 29 years, which is an increase of 10.4% over 29 years or only ~0.35% per year.

In other words, per capita energy consumption is not only increasing, but the rate of increase accelerated. The growth in per capita energy consumption was much faster during the period of 2009-2013 than during the prior 29 years.

Those figures are not EROI adjusted. It's impossible to find reliable statistics on worldwide average EROI.

However, it's totally implausible that average EROI worldwide has dropped by an amount sufficient to erase that acceleration in energy consumption. Even if EROI had been stable and had not declined at all over 29 years, and then suddenly dropped from 30 to 15 (a decline by half, which is totally implausible) in only the 4 year subsequent period, the EROI-adjusted per capita energy consumption still increased faster (0.5% vs 0.35%) during the period from 2009-2013 than during the prior 29 years.

The straightforward conclusion from this, is that per capita energy consumption is increasing, and the rate of increase has sped up, no matter what you think happened to EROI (within reason).

I don't know how you arrived at the conclusion that "usable energy ... per individual is in decline". Your statement is not compatible with the data which hitssquad just presented.

This is exactly the opposite of what energy doomers had predicted. They had confidently predicted a sudden collapse of civilization in the late late 2000s and rapid declines in energy consumption. What happened was the opposite of what they had predicted, yet again.
The consistent and severe failure of prediction from these theories implies that there is something seriously wrong with them. It's long overdue to start asking what is wrong.


Here is another post from the same thread:

Hi Harry,

I just read through the comments again, and came across yours. You said:

"Could you be very kind and point me to some of those suggestions? I am about to radically decouple!"

Harry, are you going to radically decouple because you expect civilization to collapse soon? If so, you're about to throw your life away. Civilization is not collapsing for these reasons. The most recent collapse predictions from this group are no more scientific, and no better founded, than any of their other collapse predictions over the prior decades.

This material is just totally wrong. It's littered with severe errors that invalidate its conclusions, it's ignored by almost all relevant experts, it does not meet the minimal criteria of a valid scientific theory, and it's characterized by massive, repeated failures of prediction without any corresponding correction of the underlying theories.

There have already been many people who moved out into the wilderness circa 2005 in expectation of a drastic collapse of civilization, for these reasons. They wasted ten years of their lives on a fringe doomsday theory. Do you really want to join them? Of course, you can do whatever you want, but you should clearly envision what you will feel like when five or more years have passed and civilization hasn't collapsed and not that much has happened other than you living in the middle of nowhere.

The original conversation is here.

Monday, May 11, 2015

Six Errors in ERoEI calculations

The ERoEI ratio refers to the amount of energy which we must expend in order to obtain more energy. For example, if we must use one barrel of oil in order to drill for another three barrels of oil, then the ERoEI ratio of the oil we obtained thereby is 3:1, or just 3. As another example, it may take one bushel of coal worth of energy in order to mine 10 more bushels of coal, in which case the ERoEI of the coal we obtained is 10:1, or just 10.

Different sources of energy have different ERoEI ratios. Some sources of energy (such as coal) have high ERoEI ratios, typically more than 20:1, which indicates that coal requires very little energy expenditure to obtain it. Other sources of energy, such as oil, have much lower ERoEI ratios. Some sources of energy, such as corn ethanol, take as much energy to obtain as they will yield. They provide no leftover energy to society, and have an ERoEI of 1.

The ERoEI of various energy sources has been calculated throughout various papers on that topic. There are at least 30 papers calculating the ERoEI ratio for various sources of energy such as nuclear, coal, solar PV, and others.

Unfortunately, the reported ERoEI ratios for any given energy source are often widely divergent from one paper to the next. For example, Weissbach et al[1] report an ERoEI of 75 for nuclear power, whereas another study[2] reports an ERoEI of less than 1 for the same energy source. As another example, the ERoEI of solar PV is reported as 2.3 in Weissbach et al's paper[1], and the high 30s in another paper[3]. Those kinds of discrepancies are common throughout the ERoEI literature.

Much of those discrepancies are caused by errors in the calculation of ERoEI which I will detail here. Once these errors are corrected in the offending papers, the resultant ERoEI ratios for different sources of energy become much closer together.

The errors are as follows:

Error #1: Energy returns are repeatedly treated as energy investment

It's crucial not to count energy returns as energy investment, because they are different things. It would be incorrect to include energy returns as energy investment. It would yield the wrong result. However, this mistake is made repeatedly in the papers of Charles Hall and others.

As an example, the paper[4] from C Hall (What is the Minimum EROI that a Sustainable Society Must Have?) calculates the EROI of oil. However, it includes  the energy cost of freeways, automobiles, and so on. That is a mistake, because those things are energy returns, not energy investments to obtain energy. If I drive my car down the freeway, and I'm not doing so out of necessity for gathering coal, then it was because of energy returns.

If you include all energy returns as energy investment, then the EROI of every energy source is 1. This is an application of the first law of thermodynamics. It would be highly surprising if we got more energy out of an energy source than was present within it. As a result, it is not surprising that the EROI of any energy source will converge to 1, as returns are included in the denominator. However, that does not yield any useful information, because it does not tell us how much energy is left over after obtaining the energy to provide for consumption. That is just a roundabout way of testing the first law of thermodynamics--something which has already has been tested and which could be tested far more directly. If we wish to find how much energy is left over as a return, then we must exclude returns from the denominator.

Many of the conversions of money to energy, which are found throughout the EROI literature, are implicitly committing this mistake. For example, in Hall's papers such as Spain's Photovoltaic Revolution[5] and the accompanying presentation[6]. On pp 12 of that presentation, there is a conversion of money into energy units, in order to find the energy cost of things like accountants employed by solar companies, etc. The formula presented is "At 1 Toe = 42 GJ, this represents 5.12MJ/Euro" which is derived from dividing the GDP with all energy usage in the entire country (Spain). That is a mistake, because most energy usage in the country is energy returns, not energy investment. To correct this mistake, Hall et al should take the total energy return for the country as a whole and divide it by the ERoEI which prevails for the country as a whole.

Performing this correction (assuming an average EROI of 10 for the country), by will increase the reported ERoEI of solar PV for that paper from 2.79, to 5.22. The figure of 5.22 is much closer to other reported ERoEI calculations for solar PV. This correction was performed by dividing all values by 10 which were the result of a money conversion as found in the chart on pp 12 in the above presentation[6].

Error #2: Lifetime estimates are incorrect

Many papers wrongly assume that the lifetime of an energy source is identical to its warranty period. For example, Hall et al's book[5] indicated above, and Weissbach et al's paper[1], both assume that the lifespan of a solar PV module is 25 years because that is the warranty period.

It would be highly surprising if solar PV cells failed on exactly the day their warranty expired. For example, I bought a car with a 50,000 mile warranty, but it didn't cease working at 50,000 miles.

The reason manufacturers are offering a 25 year warranty on solar cells is because they expect the vast majority of cells to last longer than that.

This error has a large effect on calculated EROI. In Weissbach et al's paper[1], the EROI of nuclear is calculated as 75 but the EROI of solar PV is calculated as 3.8, partly because nuclear plants are assumed to last twice as long as their original rated lifespan based upon observations, but solar cells are assumed to fail the exact day their warranty expires.

Even worse, many EROI papers contain incorrect aggregations of lifespan estimates. For example, C Hall's book[5] includes energy costs for things such as access roads to the solar plant, metal fence posts around the solar plant, concrete in the foundation, steel frames for the solar cells, etc. These things are grouped together with the solar cells themselves and are therefore wrongly assumed to have the same lifespan as the cells themselves. Even if the solar cells spontaneously stop working the very day their warranty expires, the rest of the plant (access roads, fences, steel frames, canals, and so on), will certainly last much longer, and would be re-used.

Error #3: Not counting embedded energy which is recovered

Papers about EROI frequently include the "embedded energy" cost of components for an energy source. For example, calculations of the EROI for solar PV often include the "embedded energy" in the aluminum frames which support the solar panels in the field.

If embedded energy is counted on the way in, then it must also be counted on the way out. These papers uniformly fail to account for the energy which is recovered when the aluminum is recycled when the frames are dismantled. The recovered energy should be counted because the aluminum will be recycled. Almost all major corporations recycle structural materials such as aluminum because they save money by doing so.

This factor alone has a large effect on the reported EROI of solar PV. Much of the energy for solar PV is actually devoted to the aluminum frames which support the panels. About 75% of the energy for manufacturing those panels would be recovered when the panels are decommissioned.

In J Lundin's paper[7], there was some confusion expressed over how much recycled material should be assumed within incoming aluminum used to build solar frames. In my opinion, the incoming aluminum should be counted as 100% virgin, and the outgoing aluminum must also be counted, and should be counted as 100% recycled minus the energy costs of recycling. This is the only correct way. If recycled aluminum is used when a power plant is constructed, then the recycled portion is displacing the usage of that recycled aluminum elsewhere, which would require precisely that amount of aluminum to be made from raw materials for something else. Thus, 100% of the aluminum used for construction of the plant should be counted as virgin. However, 100% of the aluminum which is recovered should be subtracted from energy investments (not including the energy used to recycle the aluminum) because that is displacing aluminum which would have been made from virgin material elsewhere.

Error #4: Waste heat losses are counted as energy returns

This is a recurring problem throughout the ERoEI literature. Waste heat should not be counted as energy returns because it is not usable as energy to society. The only exception is when the waste heat is actually used for something (such as combined heat and power plants), but this is rare.

This factor is parcticularly important when computing the ERoEI of oil. Oil is refined and then used as transportation fuel within vehicles. Those vehicles have engines which convert the chemical energy in fuel to kinetic energy (movement). However, the engines lose about 70% of the energy in the fuel during the conversion. This must be counted as an energy loss. As a result, the EROI of oil is overstated almost everywhere by at least a factor of 3.

In fact, it might be useful to abandon the ratio "EROI" in these cases, and adopt the ratio "thermodynamic work over energy investment" or TWoEI. It is work which we want in the economy, not waste heat.

This factor is especially important when considering the oft-repeated figure that "oil had an EROI of 100 back in 1930". This comment is frequently repeated by the doomsday prepper sect. In fact, that EROI of oil back in 1930, does not include refinery losses, nor does it count losses in internal combustion engines which were even less efficient back then. If I perform a back-of-the-envelope calculation which takes into account those two factors (100*0.7*0.15), I obtain a corrected EROI of 10.5 for oil in 1930, not 100.

Error #5: Outdated figures are used

Frequently there are large discrepancies in the EROI calculations because different technologies are assumed when calculating energy inputs. For example, there are large discrepancies of the reported EROI of nuclear power. That is partly because some papers[1] calculate the EROI using gas diffusion enrichment of uranium, while other papers calculate the EROI using centrifruge enrichment[8]. Those different assumptions will yield very different EROIs for nuclear power, because centrifuge enrichment is so much more efficient. This factor is a large part of the energy investment for nuclear power, and so has a big effect on the resultant EROI.

When calculating the EROI of an energy source, we should use the most modern technology when calculating energy inputs. We wish to know the EROI of an energy source going forward, not the EROI of an energy source if we had built it years ago.

As an example, the paper by Weissbach et al[1], in its calculations of the EROI of solar PV, assumes the Siemens process is used to generate solar PV grade silicon. However, that process has been supplanted by processes which use only 40% of the energy[9]This factor by itself increases the EROI of solar PV in Weissbach's paper from 3.8 to 6.6.

Error #6: Invalid Comparisons Are Made

The are actually different types of EROI depending upon where the boundaries are drawn for calculations. When calculating the EROI of oil, do you include refinery losses? Energy losses for the transport of oil? Waste heat losses from the car? And so on. Each one of those calculations represents a different type of EROI. Some EROI calculations attempt to include only energy inputs used for extraction at the mine mouth, whereas other EROI calculations attempt to include every energy investment in the entire economy, such as the energy investment for building rail lines to transport the coal. Those are different types of EROI.

EROI figures should not be compared if they draw the boundaries very differently. For example, there was a very famous graph from Charles Hall which makes such comparisons[9] (found here). That graph spread like wildfire throughout the peak oil community. However, that graph is repeatedly comparing different types of EROI figures which are not comparable.

For example, the comparison of the EROI of coal (about 70) to nuclear (about 10), taken from that graph. There is a big difference in the kinds of EROI for those two sources. The figure for coal is before waste heat losses are subtracted for generating electricity, whereas the figure for nuclear is after waste heat losses are subtracted. When a correction is made for that, coal has an EROI of about 24.5, compared to nuclear of 10. The discrepancy has been reduced considerably.

As another example from the same graph, oil from 1930 is reported to have an EROI of 100, whereas hydroelectric is reported to have an EROI of 30. However, the EROI of oil from does not include refinery losses and waste heat losses from interal combustion engines in 1930. Correcting these factors yields an EROI of 10.5 for oil in 1930, not 100. Of course, hydroelectric also suffers from electrical resistance losses which reduces its EROI to perhaps 25. However, the adjusted EROI ratio for oil has gone from much higher to much lower when an adjustment is made so the figures are comparable.


The six errors described above are widespread throughout the ERoEI literature. They are partly responsible for the wide discrepancy between reported ERoEI findings.

For example, Charles Hall et al's book[5]Spain's Photovoltaic Revolution, is committing errors #1, #2, #3, and #5. When I correct those errors and re-calculate, I obtain an EROI of 6.27 for solar PVnot 2.79 as reported.

Weissbach's paper[1] calculates an EROI of solar PV at 3.8. However, that paper is committing errors #2, #3, and #5. When I correct those errors, I obtain an EROI of 12.96, and not the 3.8 which that paper reported. Incidentally, that paper also calculates the EROI for solar in a cloudy site in Germany, and then generalizes that to the EROI of "solar PV" altogether. If I correct that factor also, and use the average insolation for the inhabited northern hemisphere, then I obtain an EROI figure of 22 for solar PVwhich is much higher than the reported figure of 3.8.

Finally, even the concept of EROI has problems. Perhaps net energy should be expressed or reported differently, using a different ratio. This is because EROI gives an exaggerated impression of the difference between energy sources. For example, assume a hypothetical energy source with an EROI of 10,000, and compare it to an energy source with an EROI of 10. The source with an EROI of 10,000 would require 0.0001% of its output (1/10000) to build another like it, whereas the source with an EROI of 10 would require only 10% of its output (1/10) to build another like it. In other words, a reduction in EROI of 99.99% led to a reduction of net energy output of only 10%. This is because EROI is less and less important as it becomes higher. Instead of using EROI, we should calculate net energy as 1-(EI/ER), and then express that as a percentage. For example, if natural gas has an EROI of 15 (everything included such as infrastructure), and solar PV has an EROI of 6.27 (everything included), then their inverted ratios are 93% and 84% respectively. This means that 7 percent of the energy from the gas plant is necessary to build another gas plant, whereas 16 percent of the energy from the solar plant is necessary to build another solar plant. The net energy available to society has declined by only 9% despite EROI falling by more than half. Thus, EROI figures give an incorrect impression, and should be calculated and reported differently.

When all the problems above are corrected, it's unclear if there is any significant difference in net energy between different methods of generating electricity. The highest EROI source (hydroelectric) requires 1.3% of its output to build another hydroelectric dam, whereas the lowest source (solar PV) requires 16%. This implies only that we would need to build slightly more solar cells (~15% more) to obtain the same net energy. Any EROI more than 5 or so makes little difference (20% at most). All common methods of generating electricity seem to exceed that threshold.

Certainly, we should investigate further into this matter. If any method of generating electricity has a disastrously low EROI (lower than 4 or so, everything included) then it would be very helpful for us to know about it. Hall's work is very useful in this regard, insofar as he attempts to include all energy investments, which will give us better approximations of relative EROIs. However, we must avoid the above mentioned errors in performing our calculations.

p.s. This paper should be seen as a draft. I will update it if any relevant objections are made.

Sunday, April 26, 2015

Civilization would rapidly rebound after a catastrophe

Here is a comment I wrote in response to an article. The article was asking whether industrial civilization could be reconstituted from scratch after a worldwide collapse. The author argues that it would be more difficult to rebuild, now that the best fossil fuels are depleted. I argue that it would be easier to industrialize the second time around. As follows:

I think that industrial civilization would be reconstituted fairly quickly, like within two centuries.
In my opinion, It would be FAR easier to industrialize the second time, despite fewer and worse fuels. Any reborn civilization would progress through the industrial revolution far faster, and far easier, than we did originally. That is because they would start with our technical knowledge, which would more than compensate for any degradation of fuel quality.
For the first 80 years, up until about 1790, steam engines had an efficiency of just 1%. Early steam engines lost 99% of their coal energy as waste heat. This was because nobody had invented the Watt engine, the Corliss engine, the Wilkonson boring machine, the compound engine, and the Parsons engine. Those basic inventions in steam technology increased the efficiency of steam engines from 1% to 15%. In other words, that basic technical knowledge allowed steam engines to obtain 15x as much power per unit of fuel. A triple expansion steam engine from 1890 is not much harder to manufacture than a Newcomen engine from 1790, but it provides 15x the work per unit of fuel. Simply understanding the basics of thermodynamics and how to build a more efficient steam engine, results in a 15x advantage.
Any reborn civilization would start with that knowledge. They would start with engines which produce 15x the power, per unit of fuel. That advantage would more than compensate for any degradation of fuel quality. Does coal really have 15x as much energy as charcoal? The answer is no.
If industrial civilization was able to advance with 1% efficient engines, then it would be able to advance with 15% efficient engines. That advantage would far outweigh any degradation of fuel quality.
As long as a few textbooks survive and those textbooks describe how to build such engines, then industrial civilization would bounce back fairly quickly. Any new industrial revolution would be far faster than the original one.
After that, if we retained even 15 textbooks about basic physics, chemistry, thermodynamics, electricity, inventions, and so on, it would be enough to bring us well into the 20th century fairly quickly.
(The original article, to which this was a response, is here.)