Sustainability

Sustainability is all the rage now days.  We have sustainable farming, sustainable energy, and even sustainable fashion.  Sustainable in this context means that the activity or product does not harm the environment or permanently consume any natural resources.  This might be farming strategies that restore as much nutrition to the soil as they consume, either by limiting the rate of consumption to what the environment can naturally restore through the water cycle and natural decay or by actively replacing those nutrients.  It might be energy production strategies that rely on processes that will continue to produce energy indefinitely.  The benefit of sustainability is that sustainable activities can be continued indefinitely, without ever running out of raw materials or causing so much harm that it is impossible to continue them.

Sustainability is also a myth.  There is no such thing as true sustainability.  All sustainable practices come back to sustainable energy, and energy is not sustainable, as far as modern science has been able to determine.  And let's be clear, thousands if not millions of people have tried to invent truly sustainable energy, and not a single one has been successful.  The First Law of Thermodynamics, which again, has never been broken, states that the amount of energy within a system cannot change, which means energy output of a generator cannot exceed the energy input.  Another way of saying this is that no source of energy can last forever.  Nearly all of our "sustainable" energy comes from the Sun.  The Sun depletes hydrogen gas and other heavier elements to produce energy.  This process cannot be reversed efficiently, and that means solar energy is not sustainable.  Wind energy is also a form of solar energy, as wind is created by atmospheric temperature gradients caused by solar radiation warming the air.  Hydroelectric power is also yet another form of solar energy, provided by the water cycle, which is powered by solar radiation evaporating ocean water.  Not all of our supposedly sustainable energy comes from solar power though.  Geothermal energy does not come from the Sun.  It comes from the compressive forces of about 6 × 10^24 kilograms (6.6 × 10^21 tons) of iron, rock, water, and soil, super heating most of its own volume.  More importantly, all of that thermal energy will eventually bleed out into space, leaving the Earth a cold lump of rock, metal, and ice, without any geothermal energy left for us to harvest.  Just like the Sun, the Earth's reserve of energy will not last forever.  Even geothermal power is not sustainable.  Every other form of energy we can harvest is widely known to be unsustainable.  We have already calculated an approximate date for when petroleum products will run out.  We have sufficient uranium to produce nuclear power for significantly longer than that, but even that is a very limited resource.  The same is true of other potential nuclear fuels.  Even our oceans are not big enough to produce enough fusible hydrogen for a sustainable source of fusion power fuel, though if our technology was sufficiently more efficient, fusion power could be the most sustainable power source, since its fuel is produced by cosmic radiation hitting hydrogen atoms in water.  Eventually though, the entire universe is going to equalize in energy, making it literally impossible to ever harvest energy again.  There is no sustainable power source, because even the longest lasting sources are consuming fuel in a process that is irreversible and will eventually run out.  And every other sustainable practice relies critically on sustainable energy.  Nutrients do not magically appear in the soil.  Bacterial, fungal, and animal actions produce the nutrients, in processes that consume energy ultimately provided by sunlight.  Even sustainable farming and sustainable fashion are not actually sustainable.

If nothing is sustainable, are we just stupid to be pursuing "sustainable" practices, or is it still worth doing?  We are not stupid, but we are misguided.  The concept of sustainability comes from the very wise idea of self sufficiency.  The fundamental idea is that we should protect and conserve our resources, so that we do not have to rely on outside entities beyond our control for our survival.  How many businesses have failed, because an external company supplying some raw material or fundamental ingredient went under?  How many people have ended up unable to sustain their desired lifestyle, because their employer laid them off or went out of business?  Sustainability is about self sufficiency, and self sufficiency is about having access to the resources you need, for as long as you need, without having to depend on something unpredictable for them.

If we acknowledge that the traditional definition of "sustainable" describes a property that is literally impossible, we can adjust that definition a little bit to fit the intent of our meaning and the purpose of sustainability.  This will give us a glimpse into our ideal future and how we might get there.  Let's say sustainability is not fundamentally about whether a process would deplete resources if continued indefinitely, and instead put a practical limit on the time span.  Thus, any process which would take so long to deplete the resources required for it to continue that humanity would no longer exist is a de facto sustainable process.  Similarly, any process which will not deplete its resources before we find another source to replace our current sources is also sustainable.  And of course, any process that causes so little damage that other sources of harm will cause significantly more damage before the given process causes enough damage to be a problem is sustainable.  This means, if we can find a natural resource that can be used to generate sufficient power for our needs, which will not be depleted before either, the Sun expands and destroys all life on Earth, or we find some other source of that resource that will extend our supply sufficiently to continue using it, that form of power generation is sustainable, regardless of whether it would theoretically deplete all of its fuel if allowed to continue indefinitely.  It also means that processes, like farming practices, that damage the soil are still sustainable, so long as that damage will not cause any lasting problems in the time frame from now till our Sun destroys all life on Earth.

This opens up a lot of options.  For example, we have discovered uranium on Venus.  Perhaps Venus has sufficient uranium to fuel our power needs till the Sun expands and swallows the Earth.  If this is the case, then if we can figure out how to mine uranium from Venus, before we deplete our own reserves, then uranium fission power is a sustainable source of energy, so long as we can also avoid serious harm.  Modern fission power is much safer than early fission power and all of the associated accidents, and it can be made even safer.  The biggest real concern with uranium fission power at this point is the role it can play in nuclear weapon production.  Nuclear weapons are a very unsustainable use though, because they cause very serious harm.  This is rather a tangent, but it is worth consideration, if we look at it as a side effect of uranium fission power.  For power though, uranium is not the only fission option.  To be clear, the numbers strongly suggest uranium fission power is a sustainable energy source, given our revised, practical definition.  Earth's reserves of reasonably available uranium [1] is roughly estimated to be sufficient to last us around 2.5 million years [2], if we scale the usage of every person in the world and then some (10 billion total) up to energy usage levels of those living in the most developed nations.  Estimates schedule the Sun to destroy the Earth in around 7.6 billion years, so 2.5 million is not inherently sustainable, but if we cannot find a more sustainable source of energy 2.5 million years, maybe we deserve to run out.   This is not the end though.  We are also starting to (finally) pursue thorium fission power generation.  This would approximately double our fuel reserves, giving us a total of 5 million years worth of power.  In addition, Japan is working on extracting uranium from seawater, currently costing $240 per kg.  This is a somewhat renewable process too, because as uranium is extracted, more will dissolve into the sea, essentially giving us access to massive reserves of uranium underwater.  Since 71% of the surface of the Earth is water, if we assume that sea water can dissolve as much uranium as we can extract from land [3], that increases our time before we run out to 17 million years.  And then there is Venus.  Obviously Venus would be a much more expensive source of uranium and thorium, but it does have at least comparable concentrations of uranium and thorium.  Further, current prices for these minerals are around $80 per ton, so odd are really good that we could be mining these minerals from Venus for under $3,000/kg within the next century.  This would far more than double our reserves, because Venus is uninhabited and permanently uninhabitable, meaning that we could mine far more of its surface area.  Without cities, farms, national parks, reserves, stripmining regulations, and just plain land that the owners do not want to sell to mining companies, Venus could be mined for uranium and thorium far more extensively [4].  As a rough estimate though, let's say we get just over double what we can get from Earth, from Venus.  That would give us around 40 million years worth of nuclear fuel.  There may also be uranium and thorium on Mars, and we will probably find significant quantities of these minerals in asteroids.  In short, nuclear power is incredibly sustainable.  The amounts available on Earth and Venus combined still do not even get close to competing with solar energy for how long they will last, but 40 million years gives us way more than enough time to find more sources or to find entirely alternative energy sources.  In that time, we might be able to build something like a Dyson sphere to more efficiently and directly collect solar energy.

What about solar, wind, and hydroelectric power though?  How do those fare against our revised definition of sustainability, and how do they compare with nuclear?  If you are not well educated in these sources of supposedly sustainable energy, the answer will probably surprise you.  They actually do not fare terribly well.  Hydroelectric power has been known to be harmful to the environment since shortly after the first dams were built.  Some of this can be mitigate, for instance, hydroelectric dams can prevent fish populations, notably salmon, from returning to their breeding grounds, after swimming out to the ocean.  Fish ladders were invented to mitigate this problem, but they have been shown to do a poor job of maintaining sustainable populations of fish, and they do not help all species of wildlife that are negatively affected by dams.  Many old hydroelectric dams in the U.S. are actually being decommissioned and torn down, when they become due for major maintenance, in a large part because the ecological harm they cause is not worth the benefit.  Wind generators cause similar problems with bird populations, killing both migratory birds and some larger species.  While reports are sometimes blown out of proportion, protected species, like bald and golden eagles, are at risk of being killed in wind farms built near their natural feeding grounds, like lakes and rivers.  And reports are starting to show that bird safe radar systems that turn off the turbines when birds are flying though have a very poor success rate.  At least half a million birds are killed each year by wind generators.  This may not sound like much, given that Earth is home to hundreds of billions of birds, but as wind farms become more common, those numbers will rise, and experts estimate the world bird population has declined by 1% to 2% over the last 50 years.  With the bird population already in decline, wind farms are poised to make what may currently be a fairly minor problem into a much more serious one.  In addition, wind farms reduce wind speed, and we do not know what other side effects that may have.  Scientists recently discovered that geothermal power can cause earth quakes, because it cools deeper parts of the crust, shrinking the rock and soil and potentially cooling magma that may be lubricating tectonic motion.  The only reason we do not see problems from this is that geothermal power is quite uncommon.  As wind farms become more common though, we will very likely see more dramatic affects from slowing wind speeds.  Solar power is also not blameless.  To start with, it is so inefficient that we need massive solar farms, covering vast areas of land, just to get the same power a coal plant would produce.  In our attempts to be environmentally conscious, we have built many of these in desert areas.  Not only do these areas have very little wildlife, they also tend to get far more sunlight.  Except, it is not true that they have very little wildlife.  Deserts are actually full of wildlife.  Pretty much any place on Earth that is not straight up toxic to cellular biology has some kind of wildlife living there.  This includes deep ocean thermal vents with water temperatures well above boiling.  While warm blooded life cannot survive well in deserts, cold blooded life that has adapted to the high daytime temperatures can and does.  Assuming deserts are barren of life has turned out to be a major mistake, which construction workers have discovered while building these solar farms.  The most obvious desert life that has been harmed by solar farms is turtles that use their shells for shelter during the day.  A great many of these turtles have been relocated as their habitats were destroyed to make way for solar farms.  Most desert life, however, does not live on the surface during the day, and some does not live in the surface at all.  Construction workers, who mostly worked during the day, have not relocated this vast majority of desert life, because they could not see it.  This life is either killed, when concrete foundation is poured over the sand, suffocating anything beneath, or when the shadows of the solar panels prevent the sand beneath from being warmed during the day, causing the burrowed animals to die from the cold of the nighttime desert at night.  In addition, more efficient solar power plant designs are known to sometimes burn birds alive.  Nuclear power, on the other hand, has a very small foot print, limiting its impact on ecosystems.  It does not have spinning blades, nor does it interfere in migration.  It generates far more power, meaning we need far fewer plants.  It is also safer for humans to maintain.  The only by products are heat and nuclear waste.  The nuclear waste is not terribly difficult to contain, especially for thorium plants, and the waste heat would easily be mitigated by the dramatic reduction in CO2 emissions a switch from coal to nuclear power would result in.  In short, by our revised practical definition of sustainability, nuclear is actually significantly more sustainable than solar, wind, or hydroelectric.

It turns out that nuclear power is the most sustainable energy we have the technology for.  Maybe, eventually, we will figure out how to harness solar power that is not pointed at the Earth, so that it does not affect Earth's ecosystems, but the numbers strongly suggest we have at least 17 million years just to figure out how to get nuclear fuel from places other than Earth, and well over 40 million years to find an alternative to nuclear energy.  If humanity manages to survive that long and has not managed to accidentally discover some new source of energy, then perhaps humanity does not deserve to survive.  That is not a problem for us though.  The best thing we can do right now is switch as much as possible to nuclear power, so the next generations will have access to the massive amounts of energy they will need to find the next source of energy.





[1] This includes all uranium that would cost $3,000 per kg (0.04¢ per kWh) or less to extract, not counting uranium contained in sea water.

[2] The uranium in the U.S. alone is sufficient for 50,000 years, and the landmass of the Earth is 51 times that of the U.S..

[3] The $3k per kg value takes into account the fact that we cannot just dig up 100% of the Earth's surface, because people live on some of it, and we want to maintain very large quantities for future development.  As such, sea water probably actually has access to far more available uranium per unit of surface area than land does.  This means this estimate is probably a massive underestimate.

[4] Venus actually has a bit less land surface area than Earth does, but on Earth, we would not be able to mine more than a small percentage of our land area, because any more would disrupt our own ecosystems as well as other ecosystems on Earth.  The damage done by more extensive mining than that would make nuclear power clearly unsustainable, even by our revised definition.


This is the source of the numbers on nuclear fuel cost and availability:

www.daretothink.org/numbers-not-adjectives/how-long-will-our-supplies-of-uranium-and-thorium-last/