Energy is neither renewable nor sustainable
The pressure is on to reduce greenhouse gas emissions to slow climate change. The way proposed by most people is to switch away from fossil fuels to alternatives such as wind, solar, tidal and geothermal. Such alternative energy sources are often described as ‘renewable’ or ‘sustainable’. This terminology implies to most people that such alternatives can meet our energy demands in perpetuity, without polluting the environment. This is wrong, and will lead to serious errors in policy making.
Energy generated for human use cannot be ‘green’, ‘clean’, ‘renewable’ or ‘sustainable’. These words are all part of the ‘greenwashing’ or ‘sugar-coating’ vocabulary used for the benefit of corporate or political interests, or simply words of misunderstanding. They have no foundation in rigorous scientific language or thought.
Put simply the Earth can be considered as an open thermodynamic system in terms of energy but a closed system as far as matter is concerned. The sun continues to radiate energy to the Earth, and energy is re-radiated to space, more-or-less at the same rate. Over a very long period of time (many millions of years) there is a progressive increase in entropy and a net loss of energy from the Earth to the rest of the universe but this natural process is not significant on time scales relevant to humans.
However, humans increasingly wish to convert solar radiation into different forms of energy such as electricity or fuel, that can do work. This can only be achieved by creating devices or machines to convert one form of energy into another and the resources for those devices come from the Earth’s crust. Those devices have a finite life span and depend on yet further infrastructure (transport, cities, factories, universities, police, etc.) to maintain and operate them, which in turn has a finite life span. Continued mining, refining and manufacturing is required.
The amount of energy captured from the sun by such devices can never be enough to restore the Earth to its original condition. This is determined by the second law of thermodynamics. So the process of mining, building and manufacturing, to convert and use energy, inexorably depletes and degrades the Earth’s mineral resources. It is irreversible and unsustainable. It makes no difference whether we consider solar, wind, hydro, coal, bio, nuclear or geothermal energy. They are all unsustainable according to the laws of physics.
The second law of thermodynamics also tells us that we cannot completely recycle resources that have been extracted from the Earth and refined for use (such as metals, helium or phosphate fertiliser). The greater the percentage we try to recycle, so the energy cost increases disproportionately. So whether the resources that we want to use are still in the ground or are in circulation above ground, human industry will inevitably dissipate and lose those resources.
The more people we have on the planet, and the more energy we use, the faster and more extensive is the degradation of Earth’s resources. Humanity is like a huge organic machine, using energy to mine and deplete minerals. The more energy that is put into the system, the faster the degradation occurs. Nuclear fusion energy, if it comes to be, might be particularly efficient at degrading our resources and environment (one effect of such technology may be to convert our lithium reserves into helium which will escape the Earths atmosphere and be lost forever).
Energy for human use is as unsustainable and non-renewable as mining. So to talk about ‘renewable energy’ or ‘sustainable energy’ is an oxymoron, as is ‘sustainable mining’ or ‘sustainable development’. The more energy we use, the less sustainable is humanity. The sooner that people realise this, the sooner we can embark on the process of reducing energy consumption, rather than clutching at the straws of alternative energy sources to perpetuate the unsustainable.
In subsequent posts I will show that resource limitations are just decades away, not centuries, and that the scramble for resources will increase demand for fossil fuel energy.
Johnston P, Everard M, Santillo D, Robèrt KH. (2007). Reclaiming the definition of sustainability. Environ. Sci. Pollut. Res. Int. 14(1):60-6.
Kleidon A and Lorenz R (2004). Entropy Production by Earth Systems Processes. In: Kleidon A and Lorenz R.D. (eds.) Non-equilibrium thermodynamics and the production of entropy: life, Earth, and beyond. Springer Verlag, Heidelberg. ISBN 3-540-22495-5
Our Common Future:
The Natural Step
Comments 1 to 9:
"However, humans increasingly wish to convert solar radiation into different forms of energy such as electricity or fuel, that can do work. This can only be achieved by creating devices or machines to convert one form of energy into another and the resources for those devices come from the Earth’s crust. Those devices have a finite life span and depend on yet further infrastructure // Continued mining, refining and manufacturing is required. The amount of energy captured from the sun by such devices can never be enough to restore the Earth to its original condition."
I'm interesting in /skeptical of such "2nd law" approaches to the problem. If it were true that material cannot be effectively recycled, how can one explain rainforests - or any other ecosystem for that matter? These not only effectively recycle all their materials, powered at source by the sun, they develop and evolve to do it better.
One can argue that the problem isn't the same, but doesn't this falsify your point about the difference between incoming energy and matter? There is no requirement to 'restore the Earth to its original condition', only to be able to use the energy to effectively cycle materials, in the way that any ecosystem does.
I was recently reading georgescu-rosen's take on "steady state" arguments, where he said they weren't possible because those advocating the idea had forgetten about material throughput. I don't get that: repeating myself now, but steady state ecosystems are, from one point of view, massive machines for using energy to pump a throughput of matter and constantly re-organise it. I'd say it was a category error applying the 2nd law at this level. Ultimately the sun will run out of fuel, but until that starts to happen, I can see no theoretical limit to our ability to recycle matter in precisely the way any ecosystem does.
Have you read Jane Jacobs' 1969 'Economies of cities?' Without being explicit about it, she paints exactly this picture of cities as ecosystems using energy to constantly recycle material.
Thank you for your thoughtful comments, some of which I too have wrestled with.
I am aware that there are problems applying simple thermodynamic principles to the Earth system that is not in a steady state, and some of my chemistry colleagues have warned me against doing this, but nevertheless agree that the message that I convey is correct. I find that some people prefer common sense arguments while others expect a theoretical case. So I try to use both.
The question of negative entropy and plant growth is challenging. However I am satisfied that plants obey the 2nd law. Plant growth contributes to an increase in the entropy of Earth, by making a major contribution to global water cycles, heat transfer and weather patterns. This reference addresses this point although there will be more useful references out there.
An individual plant appears to contravene the 2nd law but most people overlook the relatively massive transpiration of water. A plant appears to represent order created out of disorder, but the environment that sustains the plant undergoes a greater degree of disorder (increase in entropy). Same as a washing machine.
Plant growth contributes to the ongoing increase in entropy of the planet but since land plants have been around for 400 myr or so, the Earth apparently copes well, and plants continue to adapt to the very slow rate of change of the biosphere.
What is different is the challenge created by billions of humans demanding materialistic lives, in the last few decades.
I return to common sense arguments to say that recycling 100% of all our materials is impossible. Can you imagine a world without mining?
Many people argue with what I say, I think, because they cannot cope with the reality of what I point out. They come back to the argument that the Sun will shine for 5 b years and produce more energy than we can possible want, so surely there is not a problem. Well the truth is even more ‘inconvenient’ than the ‘inconvenience’ of global warming. We will rapidly run out of resources to make use of all that solar energy.
Interesting stuff, thanks for getting back to me. I'm a little put off by the start of that paper, which *begins* with "the purpose of life is to increase the global entropy production of the Earth in its interaction with its solar environment" and then goes on to assume it. I certainly hope not to be one of those people who want something to be true because I can't cope with reality! I just want to understand the issue, but am yet to be convinced.
Entropy applies to closed systems, doesn't it? As you say, the Earth is an open system, in terms of energy if not (very much) matter. If life wasn't able to create little eddies of low entropy against the long-term entropic tide, I can't see how life could have got started in the first place. This puts me exactly at odds with the paper you link to: the broad effect of the cellular self-organisation underpinning life has been to turn a temporary influx of energy (lasting billions of years) into equally temporary little pockets where entropy has decreased.
That must be the case, surely? You can't be saying that a rainforest is less ordered than what preceded it? If you're saying that the net entropy nevertheless increased in the biosphere, I have trouble seeing how that's the case. The flow of water is a case in point: the sun pumps absolutely collosal amounts of the stuff around the biosphere, and this is one of the key ways life uses the sun's energy to build order.
I'm trying to think of ways I can get past assertion to examples, but I can't think of anything more obvious than the simple ubiquity of life on Earth. If the process created net entropy I just don't see how life could have been possible.
None of that is to say we can necessarily maintain anything like the material levels of production we have currently, but I'm still failing to see a strong case for an inevitable entropic increase - as you say, I'm one of those people who says "while the sun shines...!" While it does, life can channel its energy into order-producing systems...?
Steve, your premise has no practical value. On this same basis, we could argue that the persistence of life on Earth over a period of 3.5 billion years is impossible, because entropy would have long removed the biosphere's ability to recycle its constituent elements and compounds.
With energy that is usable by humans, there is sufficient accessible uranium on the planet to run all of human civilisation at a power level of 30 TWe for the next 500 million years (yet I doubt we'll need fission for more than a few thousand years at most). When this is coupled to methods for creating synthetic fuels from water-derived hydrogen and recycling virtually all of our 'garbage' using plasma-arc torches, human society can indeed achieve an equilibrium function that more than meets any practical definition of sustainability.
In short, I find your article adds nothing other than as a philosophical discourse that is likely to frighten the uninformed.
Barry, you are spot on. Smith fails to understand the Second Law and frightens more than enlightens.
The translator has done an astoundingly incompetent job on that article. It's almost unreadable.
Thank you for your constructive and challenging comments, which is what we hope for on STW.org.
I accept that my article can be seen as unconstructive but it is meant to be the opposite and I will address this below.
The information that you provide on uranium is useful. Can you tell us whether the supplies of uranium you refer to are ‘reserves’, ‘resources’, or the total amount in the earth’s crust? A reference would be great.
However, it does not change my argument. We all know that there are huge amounts of energy in solar radiation, geothermal, wind, wave and uranium-fueled nuclear energy. The problem is making use of it.
The constraint in the system is not the magnitude of the energy source but the resources to convert that energy into work.
The use of any energy, whether coal or nuclear, achieves the net dissipation of our finite resources. I have watched the process in action for most of the last 6 decades during which time fossil fuels have been used to extract and refine resources for consumption by us humans. Switching to a different source of energy will not change that.
What is different today is that some resources are running particularly low, and require greater amounts of energy to find and refine them. So they are becoming more expensive. Which in turn makes energy generation (or work) more expensive.
Everyone can see this happening. It is exactly what the laws of physics tell us will happen. We have probably hit peak production for some metals already. And peak metals will translate into peak useful energy. While we can do a better job of recycling of some resources in the future, it will become increasingly more expensive.
I am mainly arguing against using the misleading terms of ‘renewable’ or ‘sustainable’ energy because they give people false expectations. By all means talk about alternative energy or future energy, but we must realize that reduced consumption of resources and energy is inevitable, which means a change in lifestyle and values.
A less materialistic and consumptive lifestyle could be a great improvement in my opinion, with the potential to improve the quality of people’s lives. The dream of ‘renewable’ energy feeds the insatiable and unsustainable appetites of humans, in my opinion. And currently this means continuing to make demands on fossil fuel consumption with consequent negative impact on climate change.
This is am interesting point that I have not heard discussed before. If you are right - and I will have to think and read about this a bit before I can offer an opinion - we do need a better term than "sustainable". However, "alternative" suffers form having negative connotations as in "alternative medicine". Does anyone have a better suggestion?
Thanks Steve for your reply.
The information on inexhausibility of uranium resources is here: http://www.mcgill.ca/files/gec3/NuclearFissionFuelisInexhaustibleIEEE.pdf
I have also written about it recently here:
Entropy does, of course, increase over time. But for practical purposes, that's not the issue. The issue is how much energy we can harness, during the length of time of our civilisation. I argue that we can sustain 30 TWe of power for 500 million years, without even deep mining. At that point the Earth will have become uninhabitable due to stellar evolution leading to a sun that is about 10% hotter than today.
We can recycle with high efficiency -- perhaps 99.9% for things like metals in plasma arc torches. What's left -- the residue, has not left the planet either -- every molecule that life has ever used is still on Earth (apart from our space shots) -- it just must be recovered or replaced from other ore sources. The point again is not that entropy does not increase, but that it does not do so at a rate that is unsustainable over any practical time scale we would care to ponder.
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