Monday, October 17, 2016

Green Energy

When I saw the CBS story:  “Most Americans are willing to pay a little more each month to fight global warming - but only a tiny bit, according to a new poll,” I thought it was time to do some investigation.  The story went on to say that if the electric bill went up by $1 a month, 57 percent of Americans would support it.  A $10 a month increase got only 39 percent support.  “At $20 a month, the public is more than 2-to-1 against it. And only 1-in-5 would support $50 a month.” Last time I looked the cost of wind and solar was very much higher than fossil fuel generated electricity – two to three times, in some cases.  On a nationwide average bill of about $110, we are talking about much more than $12 a year, closer to $50 a month or more.

But my research surprised me.  I found that over the past few years the cost of electricity renewable sources has become more competitive and continues to drop.  (See the chart showing the wholesale costs per kilowatt-hour and not necessarily the price on your bill.  The next column shows projected “leveraged cost,” different units but comparable within the same column across options.)  More government restrictions on coal and subsidies for wind and solar farms, bring the relative cost of renewables down, but do it in part by bringing fossil-fuel costs up, which will affect bills by more than a dollar a month.  How much more is still unknown.

Power Plant Type
9.5 - 15
Natural Gas
7 - 14
7 -20
Solar PV
Solar Thermal

In any case in August President Obama said:  “We'll take steps to meet the goal we set with Canada and Mexico to achieve 50 percent clean power across North America by 2025.”  This brings up another interesting point, variability.  Wind and solar are not available at all times, calm nights for example.  They are not always consistent and you can’t easily turn them on and off, or store electricity produced today until tomorrow.

There was an Economist article about three years ago addressing this problem in Germany, a leader in renewable energy.  The wholesale price of electricity actually goes negative on bright and windy days because of the unusually high supply, which threatens to overload the grid due to their inability to quickly and efficiently adjust their coal, gas and nuclear plants.  In places where utilities are required to buy solar- and wind-generated electricity first and where those systems provide a high percentage of the generating capacity (40%+), utilities can lose profits, money for future investment in delivery systems.  That may seem like a minor problem until the next hurricane or snow storm when we lose power longer due to that lack of investment in lines, and fewer crews available to make repairs.

This chart shows the degree of that variability for wind turbines in Germany in 2013.  Solar variability is similar, and the peaks may occur at the same or different times.  Their total need is around 52,000 MW, which is twice as high as the highest wind peaks.  All this demand must be consistently met by filling the gaps with power from the back-up sources like coal and gas that can be controlled by the people running power plants, not by the whims of nature.

As mentioned earlier, one way to solve this problem would be to store renewable energy for later use.  This could be done with traditional battery systems or some other mechanism, like a huge very low-friction disk powered by a motor to store it as kinetic energy until needed.  Nothing is yet available at the scale needed.

This was an interesting investigation.  Despite favorable cost movements, much more work needs to be done to implement a practical large-scale conversion to renewable energy.  To fall in love with a 50% number, when we already know 40% causes such problems in parts of Germany, while at the same time making it more difficult for the more reliable, traditional sources to operate, is a bit naïve at best and possibly dangerous.*

*The dangers of tinkering with an electrical system that we are so dependent on in our modern world move beyond the inconvenience of the lights going off.  We depend on electricity for heating, food preservation and the smooth operation of hospitals, emergency rooms and other emergency services.

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