renewables limitations

As part of the discussions stimulated by their airing of Pandora’s Promise, CNN hosted a debate between Michael Shellenberger of the Breakthrough Institute and Dale Bryk of the Natural Resources Defense Council.

That debate included some commentary that I thought was worth promoting to the front page.

A commenter named Fred, a tech who has worked in the power generation industry on hydroelectric and diesel power systems, provided the following background information for Shellenberger and others that might engage in debates about energy sources in the future.

Shellenberger really missed the ball by not mentioning the inherent energy inefficiency of the main renewables: wind & solar.

  1. Induced cycling inefficiency in the shadowing fossil fuel power plants
  2. Necessity of long distance power transmission to get rid of surpluses and import shortages due to the vagaries of wind & solar, waste energy in transmission & the energy of construction & maintenance of the transmission lines
  3. Economics of heavily subsidized fluctuating renewables favors low capital cost, low efficiency generation to backup and shadow the Wind & Solar. That is mostly diesel generation, OCGT and archaic low efficiency coal burners. Utilities are now being forced to pay expensive capacity payments to keep these inefficient generators operational.
  4. The inevitable overbuild that comes with wind & solar generation. Even renewables advocates admit that. In order to supply peak energy, winter in the north, summer in the south you need to greatly overbuild the renewables. That inevitably means throwing energy away in the fall & spring. Compounded by the fact that hydro is max in the spring, when energy demand is minimum. That is the epitome of energy inefficiency.
  5. Need to heat & power wind turbines when they are not generating electricity, especially in the north.
  6. The inherent energy inefficiency of energy storage, very much needed by wind & solar. Typically batteries with about a 70% round trip energy efficiency. Pumped hydro about 80-90%. CAES about 65%. Hydrogen about 40%. Add to that the embodied energy in all that additional infrastructure.

In his response to my request for his permission to promote his comment to the front page, Fred added the following information:

One additional point on electricity transmission. The substations, transformers, switchgear and transmission lines must be sized to carry peak load, while only carrying an average ~15% of peak for solar & ~30% of peak for wind. The actual transmission conductors are made of aluminum. A high energy input material. Normally the conductor size & number of conductors is determined by economics, the marginal cost of increasing conductor size or number of parallel conductors to reduce line loss should equal the revenue gained by the increase in available power sold.

With solar & wind you are only transmitting a highly peaked power for an average of a few hours per day, so it is not economical to reduce line loss to a minimum by adding a lot of aluminum. Thus line losses are going to be considerable for long distance transmission. An absurd fantasy to send solar from the SW to match wind from the plains. A ridiculous waste of energy.

Like Fred, I am intimately aware of the limitations of wind, solar, geothermal, biomass, and hydro energy sources. Despite all of the attractive sales pitches that have been given for the past 40-50 years, I believe that continued pursuit of them as major contributors to our energy supply will impoverish our society, even if a few people at the top of the economic heap may be able to continue to live like nobility.

This is an area where I often part with other energy observers; building large scale wind and solar power systems is inherently a bad idea. It is not because the systems do not scale well; it is because they depend on diffuse, highly variable energy flows that cannot be controlled by humans or human-designed control systems.

Bright, observant people — starting with the first people who learned to control fire — have been struggling for millennia to develop machines and systems that enabled them to control their environments. As a species, we have worked hard to eliminate the limitations imposed by nature. Why are so many people enthralled with the idea of going back to a time when weather and climate tightly limited our daily routines? Do they really believe that life without controllable energy supplies is wonderfully utopian?

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