Saturday, May 17, 2014

Long-Term Energy Supply

Subtitle: If Not Nuclear, What Then?

One of the grand questions for those who think about the future, especially the long-term future, is "what type of energy source will the world need?"   A corollary question, following the usual statement of "we will someday run out of fossil fuels", is "what will we do after we run out of fossil fuels?" 

The most common answer to the "what will we do?" question is "use nuclear power, of course!" as if that is the obvious answer.   Many, many scientists and others have concluded that nuclear power is the only long-term source of energy for society. 

I have a different view, and will expand on that here and in other posts.  One of the purposes of the Truth About Nuclear Power series on this blog is to show that nuclear power has many, many disadvantages and should never be the energy source of choice.  

Brown bear.  source: wiki commons
A story illustrates.  Two men were camping in the wilderness, which was known to have bears.   Each night before going to sleep, one man carefully put on his socks and track shoes.  The other man said, "that is silly.  If a bear wants you, wearing track shoes is not going to help you outrun the bear."   The first man replied, "I don't have to outrun the bear.  All I have to do is outrun YOU."

In the complex scheme of evaluating and developing energy supplies, a long-term source is not required to be economically superior to natural gas with its high efficiency and low construction cost, or coal with its very low energy cost.  All the long-term energy source must do to "beat the bear" is to be lower cost and safer than nuclear power.   Of course, to be used on a modern grid, the electric power must be, by law, safe, reliable, low-cost, and environmentally responsible.  

The TANP articles have shown that nuclear power cannot compete economically, and has structural or inherent flaws that make being competitive impossible.  Reasons include but are not limited to the inherent danger of radioactive fuel, extra safeguards to prevent radiation release, larger equipment due to low plant efficiency, more equipment needed just to run the plant, difficulty in following the grid's load, ridiculously long construction periods that add to interest and inflation costs, government subsidies in many forms just to coax utilities to build the plants (without the subsidies in their many forms, no one would build a nuclear plant), and smaller, modular plants have far worse economics than the grand, 1000-MW or larger plants.   The ultimate issue, though, for long-term sole-source nuclear energy is that power prices must be increased by a factor of 8 to 10 compared to present prices (this was covered in Part Two of TANP, see link)

If not nuclear power, what, then, will be the energy source of the future?  The answer is a mix of energy types, but in general they can be classified as 1) renewable and 2) regenerated.     Under the renewable heading, there are hydroelectric, onshore wind, offshore wind, solar in at least three forms, geothermal, cellulosic ethanol, photosynthesis of algae to oil, synthetic photosynthesis to split water into hydrogen for fuel and oxygen for sale, organic liquids as bio-diesel, ocean waves, ocean current, OTEC (ocean thermal energy conversion), and river mouth osmosis.   

Under the regenerated heading, there are methane capture from landfills, methane capture from cattle feedlots, methane from steam hydrogasification of organic sludge (sewage treatment plant sludge) see link, municipal solid waste to energy (see below), and the ultimate energy source: Carbon dioxide conversion to methane.  It has long been known how to convert carbon dioxide back to methane by removing the oxygen and adding hydrogen.   What is needed to make this economic is simply very low-cost energy.  More on this, a bit later in this article. 

Some of the above energy sources are non-steady, variable, and intermittent and thus require a grid-scale, economic energy storage system.  Such systems have been developed.  The most promising system is one developed by MIT and is one of the simplest: submerged hollow spheres in the medium-deep ocean to serve as pumped storage hydroelectric systems.   The surrounding ocean serves as the upper body of water, and the interior of the hollow sphere serves as the lower body of water.   Such systems can also be placed in lakes that are sufficiently deep, such as Lake Superior and Lake Michigan.   Another SLB article (see link) showed that presently, the US has grid-scale, pumped storage hydroelectric capability at just over 22 GW.  The PSH capacity is expected to increase to approximately 30 GW,

A bit more than 5 years ago (March, 2009), SLB had an article on Renewables in Outer Continental Shelf (see link).  That article quoted the US Department of Energy 2009 study that concluded there is 900 GW of energy in the offshore wind in US territorial waters.  That is very close to the installed US electrical capacity.  After allowance for intermittency issues, and a 20 percent loss from pumped storage systems, approximately 275 GW of reliable power is available from offshore wind.  

With offshore wind coupled to grid-scale storage, onshore wind providing energy to existing pumped storage hydroelectric systems or expanded to their 30 GW potential, cellulosic ethanol from the recently-published breakthrough in genetically modified lignin Poplar trees, recovered methane from landfills, cattle lots, and methane from reprocessing of bio-sludge, fossil fuel reserves can be extended for many, many years.   Even if such reserves were to finally deplete and no new technologies can be found to recover, for example, the 50 percent of oil that is estimated to remain in depleted oil fields, and methane hydrates are found to ultimately be uneconomic to recover, the renewables and regenerated fuels will be here forever.  

The municipal solid waste as a renewable fuel has great potential.  A U.S. utility patent, 7,452,392, was issued in 2008 to Peter A. Nick and his team of Southern California chemical engineers.  The system produces a medium-Btu gas from waste, and produces power by burning the gas in a power plant.  

Converting carbon dioxide to methane can be accomplished with cheap power at night, perhaps from wind.   The wind energy would split water to form hydrogen, then combine the CO2 with the hydrogen to yield methane and water.  

This has focused on the USA, to this point.  The rest of the world also has similar opportunities.  Conversion of sewage sludge to methane requires first that the sewage be captured and treated.  From there, the conversion to methane is straightforward.  Landfill and cattle waste methane are certainly available world-wide.   Different geographic features will dictate what each country selects as its power source.  It may be solar in the Sahara, for example.

Worldwide, the most significant ocean current in the world has the potential for vast electrical generation.  That current is the Southern Current, that circles the entire continent of Antarctica.  While it is in a remote area, the potential is incredible.   Similarly, the wind also blows strong and steady around Antarctica, in what are referred to as the Roaring Forties.  

The reality of renewable, and regenerated, power is the costs per kWh are steadily declining.  Meanwhile, the cost to construct nuclear power plants is increasing.  The beauty of renewable and regenerated power is there are no radiation concerns, and no long-term toxic spent fuel concerns.   

The future looks bright, indeed. 

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

1 comment:

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