Tuesday, December 22, 2015

Energy Supply in Post-Coal America

Subtitle: What Will Replace Coal in 20 Years

(Note, see Update below)
One of the several themes on SLB is energy supply, as at times articles on the Grand Game appear in which various aspects of US national and international energy are discussed.   As time permits, I conduct personal research into those various aspects.  In general, energy supply is categorized as coal, natural gas, petroleum, hydroelectric, nuclear, wind, solar, geothermal, tidal, wave, river and ocean currents, and bio-fuels such as ethanol, bio-gas, and bio-diesel.  There are a few others, too, such as municipal solid waste (MSW), waste fuel as cogeneration feed, waste treatment plant sludge conversion to methane, ocean thermal electric conversion (OTEC), and direct osmosis using fresh river water and the saline gradient into ocean water.  (Update: and algae-to-oil as another bio-fuel.  )

Many of these have several variations, so that the 20 categories listed above easily have 50 or more distinct types.  Each has advantages, disadvantages, environmental impacts, economics, resource and land-use requirements, grid impacts, and other aspects.  As an example of different grid-scale electric generating power plants, a recent study (cited in several SLB articles) by the California Energy Commission in 2009 lists 21 different technologies including baseload, peaking, and intermittent sources. ( see link. ) 

An earlier article on SLB (May, 2014) had the following, with respect to the world running out of coal in the 50 to 60 year time-frame:  (see link to "Coal Exhaustion Looms - Renewable Energy to the Rescue")

". . . 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."  

That statement is a bit vague on what reserves of coal are included, it should be improved by stating the "world economic recoverable reserves" of coal will be exhausted in roughly 60 to 70 years.  

However, the US coal domestic supply and demand picture is quite a bit gloomier: the coal will run out in approximately 20 years.  (see link to USGS' 2009 National Coal Resource Assessment Overview) That is, by 2035, every coal-fired power plant in the US will be out of fuel.  With coal-fired power plants providing approximately 40 percent of the US electricity today, see pie-chart at right, and only 20 years in which to identify and build replacement power supplies, perhaps it is no wonder that the current federal administration is pushing coal to the sidelines and assisting renewables.  The USGS shows economical recoverable reserves to be a bit more than 28 billion tons in 2009, and 1.1 billion tons annual production.  Today, six years later, the reserves are at approximately 21 billion tons, and production has declined to just under 1 billion tons per year, leaving 21 divided by 1 for approximately 20 years of coal remaining.  

Replacing the domestic coal-power can be via several alternatives: importing coal from overseas, increasing construction of natural gas-fired plants, building 200 nuclear plants, or increasing renewable production.  Of course, a crash program to reduce electricity use would also play a role, but not a very large role.   Any increased efficiencies would be offset by increased economic growth.   Another possibility is by in-situ coal gasification, gas collection, cleanup, and distribution to power plants. 

Importing Coal

Other countries are also running out of coal and are importing coal to run their power plants.  India, China, Korea, and Japan are a few examples.   Importing coal requires port and rail infrastructure to unload the ships, store the coal on shore, then load the coal into rail cars for delivery to the power plants.  A major concern is security of energy supply with coal ships shuttling over the oceans.  

Build Natural Gas Power Plants

The US has abundant natural gas due to advances in precision directional drilling and hydraulic fracturing in gas-bearing rock formations.  Gas price is low at approximately $4 per million Btu.  Combined cycle gas turbine power plants are very efficient at approximately 60 percent, and use very little water for cooling compared to coal and especially compared to nuclear plants.  CCGT can also be built rapidly and are mature technology with predictable startup dates and finished costs.   CCGT plants also have desirable operating characteristics of load-following or baseload operation.  

Build 200 Nuclear Plants

Another option to replace coal power is to build approximately 200 nuclear power plants using the Pressurized Water Reactor design at 1,000 MW each.  However, with the plants running at less than 100 percent, it is likely that at least 220 nuclear plants would be required.   But, getting 220 nuclear plants through the regulatory approval process, licenses to construct issued, and building the plants so that all start up within the 20 year deadline is essentially impossible.  Recent experience in the US with the Vogtle and Sumner nuclear plant expansions indicates that a new reactor requires 8 to 10 years to construct.  

Finding locations for the plants, and finding adequate cooling water for that many plants would also be essentially impossible.  Nuclear plants consume approximately 4 times as much water per kWh generated compared to a CCGT plant described above  (see link to "Nuclear plants use far more fresh water than other power plants").  

In addition, if the country were to "go nuclear" to replace coal, it is necessary to replace the existing fleet of approximately 100 aging, operating nuclear plants as they will (almost) all be beyond their service lives of 40 to 60 year with the passage of another 20 years time.  Therefore, the build requirement is then 320 new PWR nuclear power plants.  

Finally, the price impact on consumers, whether residential, commercial, or industrial would be catastrophic from building that many nuclear power plants, as described in some detail (see link) in "Preposterous Power Pricing."      Replacing coal power with nuclear power is simply not an option. 

In-Situ Coal Gasification

 A potential option, but one that has not shown any hope of economic practicality, is to convert the residual coal left in the existing mines into a viable form of synthesis-gas that can be brought to the surface and burned in power plants.  The basis for this is that approximately one-half of a coal deposit remains in the ground after all the economically mine-able coal is produced.   That figure varies from mine to mine.  The concept is not new and has been the subject of some research over the decades.    Even if gasification can be accomplished, a substantial hurdle exists to convey the low-Btu synthesis gas via pipeline to the power plants.   New power plants would be required, or substantial modification to existing plants to accommodate the heating characteristics of the synthesis-gas.  

Increase Renewables With Storage

After exhausting the other avenues as impractical or hopelessly expensive (other than building CCGT plants), what is left is the renewable energy systems.  Noting that 15 of the 20 generating technologies listed above are renewable, there is substantial opportunity for competition between technologies.   It is very likely that solar will be deployed where the resource is adequate, and some form of storage will accompany the solar plants.  

Wind, however, will likely be the major player in replacing coal, along with CCGT.  Wind plants require some form of storage to make the energy reliable.  Off-shore wind systems can use the submerged spheres hydroelectric technology.  There is plenty of wind offshore, with the US' Minerals and Mining Service estimating in 2009 that 900 GigaWatts of energy can be economically produced offshore the US coasts.  Half of that is along the Atlantic seaboard.  (900 GWatts is almost 10 times the installed capacity of all the nuclear power plants in the US) 


Unless some way to produce more coal from existing mines is discovered in the very near future, the US is headed to a fundamental change in the way the electric power grids are supplied.   Coal, which has powered much of the country for more than 100 years, is about to run out.  It appears that the current presidential administration is not emphasizing this fact, but has chosen the theme of Climate Change and Man-Made Global Warming due to Carbon Pollution as the vehicle to phase out coal-power and encourage renewable energy systems.  

The most likely outcome will be a combination of natural gas-fired CCGT plants with wind turbines both onshore and offshore, and suitable ocean-based storage, to meet the electricity demands.   It is little wonder, then, that Congress continues to renew the small incentives and subsidies for renewable energy systems.   The time has come for the power in the sunshine, and the wind, to step up and be counted.   

Meanwhile, the age of the nuclear power plant is essentially over.  As described in many Truth About Nuclear Power articles on SLB and in many other places, the nuclear plants are far too expensive, take far too long to build, and have unacceptable risks of radiation releases, meltdowns, and catastrophic health hazards and environmental destruction.

The next 20 years will indeed be interesting to observe.  The Grand Game in the US, as it relates to the electrical power grid, will be a fine subject to watch as all this plays out.  

UPDATE: 1 -  Extending the 20 year deadline:  Some calculations show that we have a bit more than 20 years, perhaps 40 years, if two things occur.  One, no more coal-fired power plants are built and we simply retire aging plants as scheduled over the next 20 years.   Approximately one-half of all the coal-fired plants would normally be retired and shut down in a 20-year period, given a 40 year normal service life.   That, alone, will extend the life-time of the coal reserves as less coal is produced each year.   Two, in addition to not building new plants and retiring aging plants on schedule, a reasonable fraction of the remaining least-efficient plants are shut down and their output replaced as discussed above: CCGT plants and wind with storage. 

That, then, is the key parameter to watch:  No new coal-fired plants to be built in the next 20 years, and aging existing plants are retired on-schedule or a bit earlier.  -- end update 1 )

Roger E. Sowell, Esq.
Marina del Rey, California
copyright (c) 2015 by Roger Sowell, all rights reserved


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