By  Eric B. Forsyth

November 2018/ Revised January 2019

  The recent horrendous wild fires on the west coast have certainly focused the attention of the media on the consequences of global climate change, at least, temporarily.  The extremes of weather we are experiencing are not unusual for complex systems heading for instability.  In my many years of developing and building complicated machines I have found it to be expected, although none have approached the complexity of the weather system, which can be defined as the interaction of many variables in ill-defined ways.  Many stable systems are conditionally stable, they work fine for a normal range of conditions but can go wild with an unexpected jolt.   I remember many years ago witnessing the test of a 4,000 psi hydraulic system used to control a missile which was working smoothly, then suddenly oscillations of the control surfaces got wilder and wilder until a pipe burst due to over-pressure, and a technician was injured by a jet of fluid.  And this was a simple system, but it illustrates the point.  

   On average the mean parameters that characterize our weather are changing for the worse, but it must be emphasized that spikes, departures from the average, are also going to get more extreme if the system behaves as I expect.  To look at one aspect; average sea level height, extreme surges are going to get worse for many large coastal cities throughout the world.  Underground transportation and electrical distribution are particularly at risk, defending these systems will be very expensive.  A tsunami at the same time as a storm surge could defeat all the precautions to protect low-lying infrastructure.  All these catastrophes, and the steps we take to ameliorate them, must be regarded as the symptoms of a deeper malaise and if we are to put in place a cure it must tackle the symptoms and the disease itself.  The disease, of course, is the total dependence of our western way of life on fossil fuel.  Anyone born in a westernized country in recent times has benefited, most of us live a life of ease, comfort and freedom of choice unheard of a couple of centuries ago for the average man (or woman).  When a change is forced on us by the final depletion of fossil fuel reserves this will solve the problem of carbon dioxide emissions, but the damage will have been done; the lingering effects will affect the climate for at least a century, our way of life must be by design, not unavoidable happenstance.   

   It is the nature of engineers to try to solve problems, but a solution to a change of this magnitude is far beyond the scope of a few individuals, and it will probably require a Darwinian competition of politics, social engineering, technology and economics.   I think it is safe to say current renewable technologies will never be able to permit a one for one replacement for the fossil fuel driven society we now live in. The reason is simple; fossil fuel packs a very high energy content into a unit volume.   After all, the energy was distilled into fossil fuel over uncountable millennia, but for us, lucky enough to born in the present era, it is free. Yes, the present cost of fuel only covers extraction, distribution and profit, the energy itself was stored a long time ago, just waiting for us.   Look at it this way; the industrial age we live in started about two hundred years ago and will probably last another hundred years, give or take.  Say three hundred years altogether, the fuel the human population will have consumed in that period took about a hundred million years to form, give or take.    Put another way; every year the energy the world depletes from the inherited reserve was created in about 330,000 years, just about the span of homo sapiens.   Every week we burn energy created in about 6,000 years, almost the total span of recorded human history. It will be extraordinarily difficult for the technologies presently under consideration such as wind, solar, tides and all the rest to produce energy of this scale in real time, if we are aiming for a simple substitution of one form of energy for another.  Other scientists, engineers and some economists, simply using annual reports of energy production and use, have reached the same conclusion.

  In a long engineering career, I have discovered, sometimes to my cost, that if the perceived solution to a problem is going to work, the problem itself must be very carefully and accurately understood.  On a macroscopic scale let’s try to define the problem and figure out a path to solutions.   The immediate problem is climate change and the consequences that flow from that.  Despite lofty sentiments the world community has not met the goals set in Paris three years ago to reduce carbon emission into the atmosphere and thereby, hopefully, limit long-term temperature change to two degrees centigrade.    But no-one really knows the exact relationship between carbon emission and temperature rise, it is likely to be highly non-linear.  That is to say, that at some point a small increase in emissions could produce a disproportionate change in temperature.   Thus, it seems logical to tackle the root cause of carbon emission; burning fossil fuel.   The goal of a future agreement should be a year by which the world society can function satisfactorily by virtually eliminating the use of fossil fuel.  This amounts to a gigantic re-ordering of our way of life in order to leave fossil fuel where it was made; in the ground.   The implications are enormous, fossil fuel is at present the bedrock of everyday life and the economy of many countries.  But it will happen, either by planning and design or by neglect, the stuff will not last forever.   We must envisage a society which maintains acceptable, sustainable, standards without coal, oil and gas, worldwide.

   Implementing the infrastructure for this new society is the greatest technical and philosophical problem ever faced by mankind.  As new technologies are developed, they must be seamlessly incorporated into our daily life, probably subsidies will be needed at first.   I make no pretense of trying to propose specific solutions, they will require the contributions of millions of people and the wisest leadership.  I suggest the period for this change is two generations, the goal of the next Paris Agreement should be a fossil fuel-less society by 2080.  Attempts to ameliorate climate change should continue  but all our R&D must be aimed at the elimination of fossil-fuel use, this work will of itself generate considerable economic activity that may compensate for some of the disruptive changes.  At the same time, we must find resources to deal with the on-going consequences of climate change such as rising sea level, weather extremes and disruption of food supplies, which will probably become more critical as fossil fuel use is tapered down. 

  Apart from hydro and nuclear power the only source of energy, if fossil fuels are eliminated from the balance of energy production and use, is the sun.  What I stated above, in a nutshell, is that green technology, mainly solar cells and wind turbines, are probably incapable of providing the amount of energy now produced by fossil fuels.  I find that green energy advocates are almost invariably optimistic and their predictions of how solar and wind can step up to the plate are often misleading.  We cannot afford to make mistakes about powering our future, we must have realistic predictions so that investments in R&D and infrastructure are optimized. 

  The production of energy from fossil fuel in the US is about 50million Megawatt hours per day.  Never mind if you aren’t familiar with the units.   On average for a combination of solar and wind generation one can expect a maximum output of about 20 Megawatts per km².  Because the sun is absent for about half a day and the wind doesn’t always blow all the time the energy produced is 120 Megawatt hour per km² per day, on average.   Divide these two numbers and you know roughly how much real estate is needed; 50million /120, equals 400 thousand km².  The area of the US is 10 million km^{2 (}lower48) of which about 80% is usable, i.e. not a mountain or a lake, but by no means is all of it available for energy production.   Some land is unsuitable, and we need space for cities, roads, agriculture, etc.  At an optimistic guess say 1% is available, or 80 thousand km², which must be compared to 400 thousand km² . This obvious shortfall is made worse by the fact not all green power is produced where there are users and in other areas there are more users than there is energy available.   Massive power transmission lines will be needed to equalize this inequality. The figure used in the calculation of 120 Megawatt/km² /day requires some explanation.   Based on long experience we find the average power available from solar or wind sources is about 25% of the peak rating, a factor called the coefficient of performance. Wind turbines permit some agriculture to be carried out on the land beneath the blades.    The mix of solar and wind is a compromise to optimize power and food production and deal with the loss of energy during night-time from solar.   In this calculation 30% of the land was given over to solar and 70% to wind turbines.  The ratio makes no allowance for land needed to house additional power source to provide operational safety margins. There is a significant penalty in allocating the preponderance of space allocated for energy production to wind turbines; the average energy per km² is reduced. This explains the growth of off-shore wind farms.  Other factors include rising population; power demand will grow if we try to maintain the present way of life.   The calculation indicates the US has only a fifth of the land needed to house green sources of energy to replace current fossil fuel production.

  Paths to a solution are:

• Improve the efficiency of green sources of energy production.

• Develop combined solar and wind sources at one site.

• Reduce the size of sources of green energy.

• Prioritize the use of land in favor of energy production

• Produce more power from hydro and nuclear sources

• Develop a less energy intensive way of life. 

• Develop stable electrical networks with energy storage facilities.

• Develop a means of energy export; battery ships akin to oil tankers.

• Use the oceans for energy production, e.g. biofuel

•    Find a substitute for plastics

•  All of the above

 The Chinese have an old curse; ‘May you be born in interesting times.’  I believe we have wished it on ourselves.