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
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