Forecasting the Future - Hubris or Honesty

Subtitle:  Coal Exhaustion Looms - Renewable Energy to the Rescue

"It's hard to make predictions, especially about the future," - attributed to Yogi Berra.

In any event, a few articles on SLB have alluded to the future, if not outright predicted the future.  One article made the case for Peak Oil as non-existent, and argued that the US should build several coal-to-liquids plants to help reduce the world price of crude oil see link. Another described future energy supplies, with renewables and regenerables as the primary supplies see link.  Still another described the near-impossibility of having nuclear power plants as the long-term supply of energy  see link.  Another described the outrageous power prices that would result from an all-nuclear-powered grid see link.  

For another quasi-quote:  "A foolish man maintains his opinion no matter what the facts are.  A wise man considers new facts, and modifies his opinions accordingly."  - paraphrased.  

A new fact presented itself to me a few days ago, and after giving it some thought, it is time to modify an opinion.  The new fact is that coal, that mainstay of electric power generation world-wide, is in shorter supply than I had remembered.  In fact, several reputable sources now state that world reserves of coal will be exhausted in roughly 60 to 70 years - and that is if no increase in current consumption occurs.  Yet, growing economies in several countries are increasing their coal consumption year-over-year.  China and India are on that list.   It is entirely conceivable that coal will run out in less than 50 to 60 years.  

What then, are the alternatives?   From Yogi's quote above, it may be futile to make predictions.   It was only 135 years ago when no one had electricity, because the first generators connected to a grid were started in approximately 1880.   Only 70 years ago, the first atomic energy was created - and that was a bomb, not a power plant.   How, then, can one predict the future of energy supplies 100 or 200 years into the future? 

One thing we can do is examine the existing energy mix, and see what will be available in 100 years.  We note that power is generated today by hydroelectricity from water flowing from dams, by burning natural gas in power plants, by burning coal in power plants, a small amount by burning oil in power plants, by nuclear fission in power plants, and a small amount by renewables such as geothermal, wind, and solar.   There are also some very small experimental plants for ocean waves and tides, and river currents.  

However the greatest source of modern electricity is burning coal, at 41 percent of the total in 2011 (source, IEA).  Next is natural gas at 21 percent.   The people who drill for gas are quite good at finding more as the need arises, drilling in new areas or deeper in old areas.  In addition, we know that great stores of methane exist in the cold, deep ocean as methane hydrates.    The same is not true for coal, however.  

Coal is only economic if it can be mined and brought to the surface at fairly low cost.  Indeed, coal must exist in a seam at least 2 feet thick, and at less than 4000 feet depth, or it is stranded, left in place.  CalTech's Professor Rutledge gives an excellent overview of world coal reserves in his 2011 paper.  ("Estimating long-term world coal production with logit and probit transforms,"  International Journal of Coal Geology, 85 (2011) 23-33 ).  He paints a grim picture.  Roughly, there are 500 billion tonnes of mine-able coal left in the world, and the existing consumption rate is 7.8 billion tonnes per year.  This provides approximately 60 to 70 years of coal remaining.   However, a slight positive note is that Rutledge did not include coal deposits near the Arctic, in Alaska North Slope, and Siberia's Lena and Tungus fields.   Whether those fields in the harsh, cold far north can be produced economically is an open question. 

As stated earlier, nuclear fission is not a candidate due to resource limitations, outrageous cost, and serious safety concerns.  The world is in great need, then, dire need actually, of a replacement energy source for coal and nuclear.  Together, that is nearly 55 percent of today's energy production.  

Knowing this, it makes sense to turn to the renewables: wind, solar, and ocean current.  It may also be possible to make the ocean-temperature-difference technology (OTEC) work.  If the technologies still need a subsidy to advance so they can stand alone and provide electricity at reasonable rates, then prudence dictates the subsidies be made.   

Advances in grid-scale energy storage have been made, with underwater storage in the shallow oceans an excellent candidate.  Similar systems can be deployed around the deeper Great Lakes in the US.  

Is this hubris?  Will engineers and planners of the year 2100 read this or similar articles, and get a good laugh?  It could happen.   Until some major technology improvement or discovery occurs, though, this is about the best we can do.  We can alter our grids so that power can flow from onshore turbines in windy areas to storage facilities.  We can install large, economic wind turbines offshore and store the power underwater in hollow spheres for later use.  We can maintain the improvements in solar photo-voltaics, primarily efficiency and cost reduction.  A recent announcement showed that 40 percent efficiency has been achieved in PV (2014).   We can install and test slow-speed ocean current turbines, and tap into the incredible amounts of energy in the ocean currents.   

The problem is made much, much more acute when one considers the effect of population growth, and the increase in energy-per-capita.  A growth rate in electricity consumption of only 2 percent per year will triple electricity demand in only 55 years.  (the STEM majors will run that calculation and verify it as 2.97, close enough to 3.0)   Even more sobering is that number will again triple in another 55 years.  That puts the world needing 9 times the present energy in only 110 years.   That puts Professor Rutledge's 60 to 70 years for coal-exhaustion as an optimistic figure.  We may well run out of coal long before that.  

When various governments decide to continue subsidies for wind, or solar, or fund research into alternative energies, and some decry these as a waste of money, I hope someone points this article to them.   What would the nay-sayers do?  There will be a grim day of reckoning when the coal runs out.   It would be far, far better to have proven, economic means to provide grid-scale electricity at least a decade before the coal-runs-out-day. 

It may be possible, someday, to gasify coal in-situ and collect the gasified product at the surface and do all this economically.  There is research into this.  The practical challenges are, however, enormous.  One must essentially start a fire in the coal-bed, deep underground, with sufficient oxygen to maintain the burning.  The economics of oxygen injection make the entire thing questionable.   Also, a patent from 1980 describes injecting methanol and steam into a coal bed to produce methane.  

Roger E. Sowell, Esq. 
Marina del Rey, California