Saturday, 4 July 2015

A Political Fantasy, Part 4: Renewable Energy Sources

This is another in the series of posts where I've been talking about things a government might do to ease our transition to a low energy economy, if it (the government) wasn't shackled by political realities.

The depletion of fossil fuels, and the economic contraction it's causing, is at the core of our current problems. Coming up with an energy policy which solves those problems is a major challenge, and perhaps it's a political fantasy to think it can be done.

In my last post I talked about non-renewable energy sources and "energy sprawl", which is what happens when we try to keep up with the demand for energy without considering the quality as well as the potential quantity of the energy sources we are trying to tap into.

In this post, I'll be talking about renewable energy and its limitations.

Renewables would seem to solve the major problems with non-renewables – that the supply is finite and the easy to access portion of that supply is becoming depleted, and that, in the case of fossil fuels, that burning them is causing climate change. But renewables come with a whole new set of problems of their own, and learning to live within the constraints posed by renewable energy is going to be one of our major challenges in the coming decades.

First, let me clarify what I mean by "renewable". Energy sources that are based on the sun, not just solar power, but also biomass and biogas, and the power of falling water, the wind and ocean waves, are called renewable. The sun keeps coming up every day and will continue to do so for a few more billion years. Technically, that's not forever, but it's good enough for me. The same can be said for other renewables like tidal power, which comes from the orbit momentum of the moon around the earth and the earth around the sun, and geothermal power which, depending on how deep you go, either from the sun shining on the ground or from the heat of decaying radio isotopes deep within the earth.

The tie between the quality of energy and the economy is something that governments, most economists and indeed most people in general, just don't get. It's central to thinking clearly about the energy problem and renewable energy, so I think it is worth repeating this part of what I have to say again (and again). It may even be that I'm getting better at it with practice (I hope).

The economy is actually about people working to produce goods and services that other people need and/or want. “Working” is the key word here. To accomplish work, energy must be consumed, be it food powering muscles, fuel powering engines or electricity running motors. So energy is the essential resource that enables all production. I would say that wealth in our growth based economy can largely can be defined as claims on future productivity. So if wealth is based on productivity, then it is a actually based on energy.

And it’s not just the amount of energy that we can access that's important, but also the difference between what it costs us to acquire the energy and the value of what we can produce with it – the “surplus energy”. When there is an abundant supply of surplus energy economic growth is essentially unstoppable.

In the last century, when fossil fuels were cheap and available in copious quantities, economic growth came to be accepted as the normal state of affairs. Our financial system adapted to the demand for a constantly growing supply of money by creating money out of thin air, as debt. For providing this service, banks insisted on being paid back with interest. This worked fine as long as the economy was growing and the cycle of borrowing and paying back with interest could go on. But when growth slows, we have no elegant way of dealing with debts that can no longer be repaid. Demand for goods and services decreases, companies shut down, unemployment grows and demand for goods and services decreases even further.

A good way of looking at the quality of energy is to compare the cost of energy with what it's worth – what can be accomplished using it. This is clearly expressed in the ratio “Energy Returned on Energy Invested” or EROEI, calculated as Energy Returned divided by Energy Invested. Every energy source that is available to us has a certain characteristic EROEI. It’s pretty obvious that if it takes more energy to make a fuel than you get from burning it (if its EROEI is less than one) then you’d be wasting your time. And actually, because of losses in processing and distribution (which aren't usually included in EROEI numbers), it takes an EROEI somewhere between 3 and 5 to really break even. But what isn’t so obvious is that an energy source must have an EROEI considerably higher than one (or even five) in order to drive the kind of economy to which we’ve become accustomed. It seems that if the average EROEI of the energy sources we’re using falls below about 15, the economy fails to generate enough surplus wealth to drive growth, and as the EROEI falls even further, there isn't even enough surplus wealth to maintain existing infrastructure.

In our current circumstances, it is very important to understand why that last bit is true.

When our average EROEI is well above 15, sufficient wealth is created to pay for the ongoing search for energy, accessing it, converting it into useful forms and moving it to where we need it. There is sufficient energy (wealth) to provide the necessities of life, with lots left over to keep productivity high and build more of the machinery of production, so the economy keeps growing. But as the EROEI drops off, a larger and larger portion of the wealth being created is used up just supplying the energy. When we get into an energy sprawl situation such as we have at present, so much wealth (and energy) is being put into building new energy infrastructure (energy sprawl) to access low quality energy sources that there is barely enough left over to supply the necessities of life. Economic growth has slowed down and the infrastructure of our economy is being allowed to crumble. Many governments are borrowing immense sums of money in an attempts to "jump start" the economy. But this isn't working because, to continue with the automotive analogy, the problem is not that the battery is dead, but that the gas tank is empty.

Indeed it seems very unlikely that a "business as usual", high tech, global, industrial society can be sustained with an average EROEI of less than 15. Efforts to access even more low EROEI energy just make the situation worse by gobbling up more wealth with insufficient return to improve the situation. This is what I've been calling "energy sprawl".

There's one more non-obvious aspect of this situation is that we really need to be aware of. Many of the possible renewable energy sources that we'll be talking about in a moment have an EROEI of less than 15, which means they won't support a growth based high tech industrial society, but at the same time they require a global high-tech infrastructure to support them. Let's be clear on the way this works. Yes, we could use what remains of high EROEI fossil fuels to set up the infrastructure for such renewables, solar panels for instance. And I think that, technically speaking, after the fossil fuels are depleted, the energy from these renewables would be sufficient to maintain them and even to replace them as they wear out. But there would not be sufficient energy left over to support an industrial society if we did so. And if there is no industrial society, the large scale manufacture of solar cells would not be feasible, so that "technically speaking" doesn't really help. By pinning our hopes on such sources, we're heading straight for collapse.

It is time now to talk about specific renewables, their EROEIs, and the problems and limitations that come with them.

Biomass

Biomass is sunlight (solar energy) converted by plants into sugar, starch, cellulose, lignin and so forth. People has been using biomass as an energy source for a very long time, first as food and then as firewood.

I will cover agriculture in another post, but food as a source of energy should not be forgotten. Of course, modern agriculture has an EROEI of 0.1 (yes that's "point one", and it's not a mistake), so energetically speaking it is an abject failure. But even traditional agriculture had an EROEI of about 6 and with judiciously chosen modern refinements we should be able to do even better. Food converted to muscle power, both of people and draught animals, is low tech and very effective in many situations. It is under-utilized today, because we have accepted labour efficiency as the main metric for judging success in business.

Firewood has an EROEI range from 13 to 40, depending on the type of wood and how far the tree is from where it will be burnt. But it can be used at the very lowest levels of technology, by anyone who can pick up deadwood and start a fire. With modern, clean burning, high efficiency wood stoves (which certainly aren't high tech) it can be used quite effectively and at fairly low levels of air pollution. Of course, people do have to be trained to burn wood properly. And firewood is still probably not suitable in areas of high population density due to air pollution and having to ship the wood a long way from its source.

Wood, unfortunately, has a lower energy density than any of the fossil fuels, and it isn't nearly as convenient to handle as any of the liquid fuels that can be refined from crude oil.

We are, in fact, quite desperate to find a renewable replacement for those liquid fuels. So far, the results are not encouraging. Ethanol from corn has an EROEI of around 1.3. Corn biodiesel has an EROEI of 3. Ethanol from sugar cane has an EROEI of around 5. Ethanol from cellulose has an EROEI of around 4. These low numbers are a reflection of the reality that sunlight is not a very concentrated sources of energy, that plants are not very efficient at converting it into sugars, starches or oils, and that growing these plants and turning them into alcohol or biodiesel takes energy as well. It also takes a great deal of land to produce to produce liquid fuels in the quantities we've grown used to.

It is possible to make biodiesel from algae grown in clear tubes to maximize their exposure to sunlight, but thus far the EROEI is less than 1, so that clearly is not going to help.

There are a couple of other ways of turning biomass into fuels, but in both cases the fuels are gases.

Biomass that is decaying anaerobically (without oxygen) gives off methane gas, in this case called "biogas". The EROEI of this process is about 7.9, so it is probably worth doing in cases where the gas would just be released to the atmosphere anyway, on farms with lots of manure, or in cities where human waste could be collected and used for this purpose. Unfortunately, current sewage systems add too much water to the waste stream.

Biomass can also be broken down into a flammable gas consisting of hydrogen and carbon monoxide(wood gas), simply by heating it in an oxygen starved environment. This gas can be used directly or processed into more conventional liquid fuels. I haven't been able to find any EROEI figures for this process, but indications are that it would be better than cellulosic alcohol, somewhere between 5 and 10 for direct use of the gas, lower if further processing is done.

There are a few other things to remember about using biomass as an energy source.

Forests grow at a certain rate and if we harvest wood at a faster rate, soon the forest is gone. If we were to switch over much of our current energy use over to wood the countryside would soon be completely stripped of trees. We need to engage in a urgent program of reforestation if we're going to start burning a lot more wood.

While vast plantations of the same type of tree planted in nice rows at the same time are easy to harvest, after a generation or two yields decrease, and if the trees are all cut at once, the land is left unprotected from erosion until more trees are planted and grow. A mixed forest that supports a more complete ecology is more sustainable, especially if harvesting is done by "single cutting" trees as they mature. And the nutrients taken out of the soil by the trees need to be replaced, at the very least by returning the ashes to the forest.

Indeed, when any plant grows, it take nutrients from the soil and those nutrients must be replaced be replaced if the practice is to be sustainable. Modern agricultural practices don't do this, so alcohol from corn grown using non-renewable fertilizers can hardly be called a renewable fuel.

A certain amount of organic matter needs to go back into the soil to maintain healthy soil, so all the biomass that is produced on a piece of land can't be burnt, or the organic matter content of the soil drops off, reducing its ability to hold water and nutrients and resist erosion.

So, desperate as we are for a renewable, high energy density liquid fuel than can replace gasoline and diesel, especially for use in transportation, it seems that biomass isn't going to supply us with one at a suitably high EROEI. We'd actually be better to concentrate on not needing nearly so much of the kind of transportation that is powered by those fuels. And return the land that is currently being used to grow corn and sugar cane back to growing food.

Firewood does seem to be such a practical, high EROEI source of energy that every bit of land not suitable or needed for growing food should be reforested.

Wood gas and biogas are in that intermediate range of EROEI between 5and 15, and the technology needed to make and use them is not extremely high. So where the feedstock is readily available, perhaps as a byproduct of process we already want and need to be doing, then it is probably worth developing these sources of energy.

On top of all this, it is important to carefully balance biomass production with food production, lest the demand for energy drive up the price of food and leave more and more poor people hungry.

This is probably the right place to mention the idea of burning garbage to generate electricity. This can certainly be done, with equipment that isn't particularly high tech. But it is not scalable because we can't readily expand the supply of garbage and indeed we would like to eliminate garbage as much as possible, because of the waste it entails, both of materials and energy.

Direct solar

What about using energy from the sun directly? There are several problems with that.

Solar energy is quite diffuse so large areas of collectors are needed to capture a significant amount of energy. Solar energy is intermittent, on the regular day and night cycle, and randomly as clouds obscure the sun, so if you want continuous power some form of energy storage is required, which reduces the EROEI by approximately half. At high latitudes the sun is at a lower angle in the winter, providing less energy exactly when more energy is needed.

Photovoltaics (solar panels which generate electricity) have an EROEI of only about 6.8, perhaps half that if you include storage, and require a high level of technology to produce. So despite their great popularity, they aren't at present the answer to our energy problems. Perhaps more research should be done to develop solar cells that can be manufactured using a lower level of technology, so that they can fit into the kind of tech level that can be maintained at an average EROEI somewhere between 5 and 15. But it doesn't seem that this has occurred to anyone in a position to do something about it.

In the face of seemingly boundless enthusiasm for solar electric power, I'd like to do a little "back of the envelope" calculation. I happen live a few miles from one of the largest nuclear power stations in the world. To match Bruce Nuclear's output (over 6 gigawatts) would take an array of solar cells over 400 square kilometers in size (a square 20 km on a side), and cost over $3 trillion. And that is only at noon on a clear summer day. To match BNPD's output round the clock would require a much large solar array with storage facilities that are beyond current technology.

By way of comparison Bruce Nuclear Site is around 900 hectares (9 square kilometers) in area and cost less than $15 billion to build. I make this comparison not as a booster of nuclear power, but to give some idea of how large and expensive utility scale solar power installation would be, if we were foolish enough to try to build them.

Solar CSP has an EROEI around 19, half that with storage. This is a moderately low tech system where mirrors focus sunlight on tubes full of fluid which boils and drives turbines which power generators.

Solar water and space heating have EROEIs around 10 and are moderately low tech.

Hydro Power

Water power has an EROEI ranging from 11 to 267, depending on circumstances. The technology required to harness water power (dams, turbines and generators) is not terribly high, late 1800s level for electrical generation, much less if the energy is to be used directly for mechanical purposes as in a water mill. The flow of water typically varies somewhat on a seasonal basis, but is much less intermittent than solar or wind, and with a large head pond this sort of energy can actually be stored. The limiting factor is that there is only so much water flowing downhill and only in specific locations.

There are also some environmental impacts of large hydro developments that need to be considered. Depending on the geography, large areas may be flooded when a dam is built. Fish that spawn upstream can't get around dams, unless special "fish ladders" are built. Silt which would normally be washed downstream by the river will build up behind the dam. This is a long term problem for the power station itself, and it can also have negative effects downstream where that silt would have enriched the fertility of the soil on the river's flood plain. But there are ways to mitigate these effects, if we care about the environmental side effects of our energy system, rather than treating them as externalities that can safely be ignored and dealt with by future generations. And we certainly should care about that.

There aren't a lot of large scale hydro power sites that haven't yet been developed, but there are lots of small scale sites, which haven't yet been developed or, more commonly, were abandoned when grid power became available and they were no longer competitive.

There are a few locations (3 or 4) in the world where there is a sufficient concentration of water power to support a localized high tech civilization of a few million people, about 50 million total. This has been studied in some detail by Jack Alpert, a fellow I met at the Age of Limits conference in 2014. The practical stumbling block is reducing our population down to that level, which makes me doubt it will ever be attempted. But if we are willing to accept a somewhat lower level of technology we can get by with smaller concentrations of people and power, spread over more of the world, and a large total population supported, especially if we add a few other reasonably high EROEI sources of energy into the mix.

Wind Power

Wind power has an EROEI of around 18. It is randomly intermittent and varies according to location. It is low tech if it can be used just when the wind is blowing, but a nightmare to hook up to a power grid and by the time measures are included to cope with the intermittent supply, the EROEI is much lower.

Wave, Tidal and Geothermal Power

Tidal power, wave power and geothermal power all have EROEIs ranging in the range of 5 to 15. This can vary quite a bit depending on the location. So too, can the level of technology required to access the energy source. In a world hungry for energy, any moderately plentiful local resource that can be access at a fairly low level of technology and has an EROEI above 5, should be developed.

Summary

When formulating an energy policy, it is extremely important to keep in mind the debilitating economic effect of investing in lower EROEI energy sources. It is so tempting to spend a lot of money on "energy sprawl" in an attempt to tap into those resources, especially if you're trying to keep "business as usual" alive as long as possible. But it won't work.

We are currently observing this with oil. Conventional (cheap) oil peaked around 2005 and since then we've been using various type of unconventional (expensive) oil to keep up with demand. Initial this drove the price up over $100 per barrel, but this had such a negative effect on the world economy that demand fell off and with it, the price of oil fell to around $50 per barrel, below the cost all unconventional sources of oil and many conventional ones.

If we were to develop any of the low EROEI renewables something similar might happen, but more likely since energy demand has already started to fall, we will never have the where-with-all to do so in any large way. The future of corn alcohol, for instance, is determined largely by how long the American government can keep up the subsidies.

So, what renewable energy sources we should be investing in?

Based on EROEI and the level of technology required, the main ones would be food and firewood, hydro, wind, solar CSP and solar heating. Biogas, wood gas, tidal, wave and geothermal should also be considered depending on local circumstances. The result of switching over to these renewables with be two-fold. First, we will probably end up with an average EROEI below 15, or at best not far above it. Second, the total amount of energy available will be much less than we are now using, perhaps 10% to 20% of our current energy consumption. Taken together, that means the economy will not only have to quit growing, but will actually have to contract significantly.

It seems unlikely to me that large scale electric grids will be sustainable under such conditions. The so-called smart grids that are being developed will prove too complex and not resilient enough due to their high level of optimization and efficiency. Because of the intermittent nature of many of the renewables, and the lack of suitable storage technology, we will have to change our energy use to match energy availability.

All of this means backing off from our current addiction to high tech and adopting more "appropriate technology", at a somewhat lower level, adopting the "LESS" approach to consumption: less energy, stuff and stimulation, and deciding to be happy with having "just enough". I'll talk about how our patterns of energy use need to change in my next post, but I will say now that I don't believe we need fall back to anything like a medieval level and certainly not to the stone age. In fact, I am willing to say that we need fall no further that the level of Japan during the Edo period (1603-1868). This was a society with a steady state, sustainable economy which relied on food and biomass for energy. And which was in many ways more civilized than Europe at the same time. Of course, this is provided we can respond to our current challenges in a reasonably intelligent fashion (though no more intelligent than the Japanese of 400 years ago). I can highly recommend the book "Just Enough – Lessons in Living Green from Traditional Japan", by Azby Brown.

Note that on my list of the renewables that we should be using, "food and firewood" come first. This is because, while I don't believe we need fall very far, if we keep on the way we are going things could fall considerably further. Food and firewood can carry us through with very simple technology while still yielding a fairly high level of EROEI. With what we now know (that we didn't 1000 years ago) and with modern industrial civilization as a starting point, we should be able to do rather well for ourselves and go on to redevelop the rest of that list of energy sources. Of course, if we are fortunate, or if our governments were to plan ahead and develop suitable energy policies, the switch over to renewables and the descent to lower levels of energy use could take place in a more organized fashion with a lot less pain involved. And under such ideal circumstances, we may indeed manage not to fall nearly as far as Edo Japan's level.

Having food and firewood as an energy safety net will be especially important for those who fall out of the consumer economy. It seems that this economy is bent on keeping itself profitable by eliminating its labour expenses, even though this at the same time eliminates the consumers on which it depends to maintain the demand for its products. But rather than worrying about keeping the consumer economy going, we should be concerned with how to carry on without it, and access to energy is an important place to start.

In order for food and firewood to serve as an energy safety net, we need to undertake a major program of reforestation and get started switching over to sustainable farming methods, the subject of my "post-after-next". Both these items should be a major part of our energy policy.