Engineering in an Age of Limits

Discusses the role of engineers as society enters an Age of Limits — particularly with oil supplies.

18. Solving the Wrong Problem

Engineering in an Age of Limits

Post #18. Solving the Wrong Problem


Engineers did not invent the steam engine — the steam engine invented them.
What will a post-oil society invent?

This is the eighteenth post in the series “Engineering in an Age of Limits”. We are facing limits in natural resources, particularly oil; our finances (money seems to be increasingly disconnected from actual goods and services); and the environment as we continue to dump waste products into the air, the sea and on to land.

We are also facing a transition as the Oil Age comes to an end. This is not the first time that society has faced such a shift. At the beginning of the 18th century the principal source of energy in northern Europe was wood. However the forests were mostly depleted so a new source of energy, coal, had to be developed and exploited. The extraction of coal from underground mines posed new technical challenges particularly with regard to removing the water that flooded those mines. So new technologies, particularly the steam engine, had to be developed. Necessity was indeed the mother of invention. These technological developments led to many changes in society, including the creation of the profession of engineering. The transitions that we are currently experiencing as we look for alternatives to oil are likely to generate equally profound paradigm shifts.

In this blog we consider two questions:

  1. What new paradigms, new ways of looking at the world, will develop, analogous to the development of engineering in the early 18th century; and
  2. How can engineers and other technical professionals help navigate the troubled waters that we are entering?

These posts are published at our Welcome page. We also have a LinkedIn forum that you are welcome to join. 

Trickle Down Phytomass

If I had an hour to solve a problem I’d spend 55 minutes thinking about the problem and 5 minutes thinking about solutions. 

Albert Einstein

Just when you thought that things could not get any worse they get worse.

Most ‘Age of Limits’ discussions revolve around the use of fossil fuels: the coal, oil and gas that was formed from the remains of photosynthetic plants hundreds of millions of years ago. We are both using them up (resource depletion) and also turning them into waste products such as CO2 in the atmosphere and acid in the oceans that are killing the environment. These problems are bad enough, but it turns out that the real concern is to do with the the earth’s inventory of living plant and animal material because that is what nourishes us, either directly or indirectly.

The technical term for this living material is phytomass.

Phytomass is critical to the survival of human beings because all of the food that we eat comes from living organisms. The energy stored in fossil fuels can help us extract and use that food more effectively but it does not create food. A person cannot eat a lump of coal or drink a barrel of oil. Phytomass is also vital because it maintains biodiversity and biochemical recycling.

In her latest essay at Our Finite World Gail Tverberg references the paper Human domination of the biosphere: Rapid discharge of earth-space battery foretells the future of humankind (lead author John R. Schramski). Published in June 2015 the paper compares the earth to a battery that has been trickle-charged for hundreds of millions of years by energy from the sun. The energy has been stored as biomass, some that is living now (mostly as trees) but most of which is stored underground in the form of oil, gas and coal. The authors argue that humanity is rapidly and irreversibly discharging that battery. They compare the earth to a house whose only electrical power comes from a battery. While the battery is charged all is well. But once it is discharged it is no longer possible to live in the house, except in the most rudimentary way.

The paper states, “Living things use photo-synthesis to convert diffuse but reliable sunlight into energy-rich organic compounds, and they use respiration to break down these compounds, release stored energy and do the biological work of living . . . humans also use technological innovations to burn organic chemicals and use this extrametabolic energy to do the additional work of fueling complex socioeconomic activities.” In other words, over a time span of hundreds of millions of years the earth’s battery has been trickle charged by sunlight being converted by plants into biomass. We are now using up that biomass and running down the battery.

With regard to the energy stored in fossil fuels there is nothing new in the above statements — the depletion of these resources is a central element of the Age of Limits thesis. However, what is new to most of us is that it is the energy stored in living biomass that really matters to our survival. After all, humans lived in rough equilibrium with the planet for tends of thousands of years. It was only with the start of the industrial revolution 300 years ago that the balance was thrown badly off kilter.

The paper estimates that the total energy stored in the earth’s current inventory of phytomass is 19 ZJ (zetajoules) and that 2 ZJ of new phytomass is created each year by plants from sunlight. (A zetajoule equals 1021 joules and is roughly half the amount of energy used by humanity per year.) “An input of 2 ZJ/y of photosynthesis maintains a standing stock of 19 ZJ of stored biomass.” In other words, if humanity were to consume phytomass at a rate of 2 ZJ per annum then we would be in balance with nature. But, needless to say, we are not so sensible.

In fact, in addition to irreversibly using fossil fuel resources, humans are also depleting the earth’s store of phytomass. The authors estimate that its value 2,000 years ago was around 35 ZJ but that now, as already noted, it is down to 19 ZJ. Causes for this depletion include deforestation, over-fishing and paving over vegetated landscapes. And the rate at which we are depleting the phytomass is increasing due to population growth and increased use of energy and phytomass per head of population. The authors of the paper calculate that humanity is consuming something like 0.53 ZJ/y more than is being replaced by the trickle down energy from the sun. This number is likely to increase as the population grows and as people strive for a higher material standard of living.

The Wrong Problem

To put it plainly, it looks as if we have been trying to solve the wrong problem. 

Our fundamental challenge is not the conservation of fossil fuel resources, nor is it reducing our impact on the environment. Our fundamental problem is that we are depleting the earth’s inventory of phytomass. Resource and environmental problems are secondary.

The chart shown below is from the journal Nature. The red line shows that startling growth in total energy consumption that has occurred in the last 300 years.

Total Energy Consumption

Based on information such as that shown in the chart the authors of the paper calculate that humanity has round 1,029 years left before the earth’s store of phytomass is exhausted. This sounds bad enough, but it is overly optimistic for the following reasons.

  1. No all phytomass can be consumed — a large proportion of it consists of trees, and we cannot eat wood.
  2. Although we cannot directly consume the energy in fossil fuel (we cannot eat lumps of coal) we still need that energy to extract phytomass energy through activities such as the manufacture of synthetic fertilizers. And, as we have discussed many, many times fossil fuel energy is declining.
  3. Human actions such as the reduction of biodiversity and pollution of the seas and atmosphere will reduce the rate at which phytomass is created.
  4. The earth’s human population (the blue line in the chart) continues to grow, at least in the short and medium term.

Therefore the value of 1,029 years before the store of phytomass is gone is probably wildly optimistic given the trends. Therefore the red line, the total energy consumed by humanity, will grow with it.

The unspoken assumption in most Age of Limits discussions is that if we can somehow control our use of fossil fuels then all will be well and we will be able to maintain our current lifestyle, or something close to it. Based on the insights of this paper such a conclusion is hopelessly naïve. Moreover, non-biological sources of energy such as wind, tidal power or nuclear energy are all essentially immaterial to the central problem — which is that we need phytomass to live; all that these  other energy sources can do is help us create and extract phytomass more effectively, thus ironically bringing about our demise even more quickly.

End Point

Schramski and his colleagues are saying that it is not enough to achieve a balance with our resources and environment — the current balance is unsustainable. We must cut back both the total population and we must drastically reduce our per capita consumption of phytomass. Simply stopping growth is not enough — we need to drastically shrink our presence on this earth because, “Unless phytomass stores stabilize, human civilization is unsustainable”. 

The authors go on to say,  “Living biomass is the energy capital that runs the biosphere and supports the human population and economy. There is an urgent need not only to halt the depletion of this biological capital, but to move as rapidly as possible toward an approximate equilibrium between [photosynthesis] and respiration. There is simply no reserve tank of biomass for plant Earth. The laws of thermodynamics have no mercy. Equilibrium is inhospitable, sterile, and final . . . the laws of thermodynamics offer little room for negotiation.”

I started this post by noting that I ran across the Schrmaski paper at the Finite World site. One of the commenters there, Fast Eddy, showed the following picture and said, “If that paper is correct… this is the future”.

Dead Plant Earth




The above sub-title comes from Voltaire’s book Candide, a work that I have referred to in previous posts. His satirical writing can be seen as a work of optimism in spite of all the bad things that take place. Therefore, where possible, I will end these posts with a few words of optimism.


After reading and thinking about the paper Human domination of the biosphere I can think of little to be optimistic about. We will have to drastically cut back on our energy consumption and on our depletion of phytomass. We need to reduce our energy consumption so that it is no more than what trickles down to us from the sun and is then converted to living plant and animal material. But, based on what we see around us, it would appear that the chances of us doing so voluntarily are slim indeed.

This line of thought takes us inexorably back to Voltaire’s Il faut cultiver notre jardin. Live simply, grow your own food and hope for the best. But there is one other conclusion that can be drawn from the above line of reasoning. Maintaining the world’s vegetative cover and diversity of plant and animal life is not just something we ought to do — it is something that is vital to our existence.


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3 responses to “18. Solving the Wrong Problem

  1. Etienne Bayenet August 9, 2015 at 11:47 am


    I believe that the problem is even worse than what it seams in this post. We don’t just need to reduce our phytomass use in order to stabilize it, but we need to reduce it so much that others who don’t use much of it now can have more of it. Maybe we are even running out of time to find a fair deal among humankind. We used to be world powers, first Europe, than the USA, but things are changing and nobody knows how much time we have left.

    Lets be optimistic and hope we find a way, best regards,



  2. suttonbooks August 10, 2015 at 2:39 pm

    But there is no evidence that we will behave in that manner. We have never done so in the past.

    This whole phytomass issue opens up a new way of thinking — it does seem as if our focus on resources and the environment is missing the point. I certainly welcome any feedback on this topic since it is new to me.


  3. Etienne Bayenet August 12, 2015 at 12:24 am

    I agree that it is not the way it works, and fair is a very difficult concept to manage. Fair trade is a good example, it works fine when the process is still very much manual like for clothes production, but what would be the fair price for ore when some work with wheelbarrows and other with huge trucks and machines, when geology is so different ? Same thing with the phytomass, what is a fair use per person when one lives in Florida, and the other in Greenland ? When one has a new passive house and the other a 1960’s house ? In the “Do the math” blog, Tom Murphy shows very well how much energy use at home depends of the behavior, furthermore thermalcomfort is well known to be a very personnal thing. In my home, I found that most of the energy efficiency improvement I made where at the end more comfort improvement than energy efficiency improvement. Regulation (like the european regulation about lightbulb efficiency, or about fuel efficiency for cars in the US) can help a lot, it is the only way I can think of to really reduce phytomass usage.

    Best regards,



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