FT142: “Solar and wind power would take the longest to restore after a devastating weather event.” —Old Pithy

Posted by PITHOCRATES - November 2nd, 2012

Fundamental Truth

Neither Snow nor Rain nor Heat nor Gloom of Night Stays the Production of Electric Power from Coal

What’s the best way to generate electric power?  This is not a trick question.  There is an answer.  And there is only one correct answer.  Coal.  A coal-fired power plant is the best way to generate electric power.  Coal-fired power plants can run 24 hours a day, 7 days a week, 365 days a year.  You never have to turn them off.  They can produce an enormous amount of power for the given infrastructure.  You can put these power plants anywhere.  Where it’s snowy and cold.  Where it’s bright and sunny.  Where it’s cloudy and rainy.  It doesn’t matter.  Coal-fired power plants are like the US Postal Service.  Neither snow nor rain nor heat nor gloom of night stays the production of electric power from coal.

Coal is a highly concentrated form of energy.  Burning a little of it goes a long way.  This is why one coal-fired power plant can add over 2,000 megawatts to the electric grid.  And why about 600 coal-fired power plants can provide over half of our electric power needs.  Coal is one of the most abundant fuel sources in the world, too.  In fact, America has more coal than we can use.  This high domestic supply makes coal cheap.  Which is why coal-produced electric power is some of the cheapest electricity we have.

The only thing that will shut down a coal-fired power plant is running out of coal.  Which doesn’t happen easily.  Look around a power plant and you will see mountains of coal.  And conveyor systems that move that coal to the firebox that burns it.  You’ll probably see more coal arriving.  By unit train.  Trains with nothing but coal cars stretching a mile long.  By river barge.  Or Great Lakes freighter.  Making round-trip after round-trip from the coal mines to the power plants.  We’ve even built power plants near coal mines.  And fed those plants with coal on conveyor systems from the mines to the power plants.  Trains, barges and freighters use self-contained fuel to transport that coal.  And electric power energizes those conveyor systems.  Electric power that comes from the power plant.  Making it difficult to interrupt that flow of coal to our power plants.  Onsite stockpiles of coal can power the plant during brief interruptions in this coal flow.  When the lakes freeze they can get their coal via train.  And if there is a train wreck or a track washout they can reroute trains onto other tracks.  Finally, coal-fired power plants are least dependent on other systems.  Whereas a natural gas-fired power plant is dependent on the natural gas infrastructure (pipelines, pumps, valves, pressure regulators, etc.).  If that system fails so do the natural gas-fired power plants.

Solar Panels produce low DC Currents and Voltages that we have to Convert to AC to Connect them to the Electric Grid

Neither snow nor rain nor heat nor gloom of night stays the production of electric power from coal.  But they sure can interrupt solar power.  Which won’t produce much power if there is snow or rain or night.  Giving it one of the lowest capacity factors.  Meaning that you get a small fraction of useful power from the installed capacity.  Wind power is a little better.  But sometimes the wind doesn’t blow.  And sometimes it blows too strong.  So wind power is not all that reliable either.  Hydroelectric power is more reliable.  But sometimes the rains don’t come.  And if there isn’t enough water behind a hydroelectric dam they have to take some generators offline.  For if they draw down the water level too much the water level behind the dam will be below the inlet to the turbines.  Which would shut off all the generators.

Of course, hydroelectric dams often have reservoirs.  These fill with water when the rains come.  So they can release their water to raise the water level behind a dam when the rains don’t come.  These reservoirs are, then, stored electric power.  For a minimal cost these can store a lot of electric power.  But it’s not an endless supply.  If there is a prolonged draught (or less snow in the mountains to melt and run off) even the water level in the reservoirs can fall too low to raise the water level behind the dam high enough to reach the water inlets to the turbines.

Storing electric power is something they can do with solar power, too.  Only it’s a lot more complex.  And a lot more costly.  Solar panels produce low DC currents and voltages.  Like small batteries in our flashlights.  So they have to have massive arrays of these solar panels connected together.  Like multiple batteries in a large flashlight.  They have to convert the DC power to AC power to connect it to the grid.  With some complicated and costly electronics.  And any excess power these solar arrays produce that they don’t feed into the grid they can store in a battery of batteries.  And as we know from the news on our electric cars, current battery technology does not hold a lot of charge.  Barely enough to drive a 75 mile round-trip.  So you’d need a lot of batteries to hold enough useful power to release into the grid after the sun goes down.

Storms like Sandy would wipe out Solar Arrays and Wind Farms with their High Winds and Storm Surges

When a 9.0 magnitude earthquake hit Japan in 2011 the Fukushima Daiichi Nuclear Power Plant suffered no damage.  Then the storm surge came.  Flooding the electrical equipment with highly conductive and highly corrosive seawater.  Shorting out and destroying that electrical equipment.  Shutting down the reactor cooling pumps.  Leading to a partial reactor core meltdown.  Proving what great damage can result when you mix water and electric equipment.  Especially when that water is seawater.

Hurricane Sandy hammered the Northeastern seaboard.  High winds and a storm surge destroyed cities and neighborhoods, flooded subway tunnels and left tens of millions of people without power.  And they may be without power for a week or more.  Restoring that power will consist primarily of fixing the electric grid.  To reconnect these homes and businesses to the power plants serving the electric grid.  They don’t have to build new power plants.  Now if these areas were powered by solar and wind power it would be a different story.  First of all, they would have lost power a lot earlier as the driving rains and cloud cover would have blocked out most of the sun.  The high winds would have taken the windmills offline.  For they shut down automatically when the winds blow too hard to prevent any damage.  Of course, the high winds and the storm surge would probably have damaged these as well as the power lines.  While shorting out and destroying all of that electronic equipment (to convert the DC power to AC power) and the battery storage system

So instead of just installing new power lines they would have to install new windmills, solar arrays, electronic equipment and storage batteries.  Requiring long manufacturing times.  Then time to transport.  And then time to install.  At a far greater cost than just replacing downed wires.  Leaving people without electric power for weeks.  Perhaps months.  Or longer.  This is why using coal-fired power plants is the best way to generate electric power.  They’re less costly.  Less fragile.  And less complicated.  You just don’t need such a large generating infrastructure.  Whereas solar arrays and wind farms would cover acres of land.  And water (for the wind farms).  And storms like Sandy could wipe these out with their high winds and storm surges.

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Hydroelectric Dams can’t make Electricity if it doesn’t Rain

Posted by PITHOCRATES - July 21st, 2012

Week in Review

Some people like to think that renewable energy is the energy of the future.  And that it will be free and abundant.  But with today’s technology it is none of these things.  It is just too unreliable.  And has such low capacity factors (CF).  The CF is a rating we calculate by dividing actual power produced by the amount possible under ideal conditions over a period of time.  Solar panels have a CF of about 20% because there are nights and cloudy days.  Wind farms have a CF of about 30% because there are times the wind doesn’t blow.  Big hydroelectric dams have a CF of about 50%  because there are times when it doesn’t rain (see Erratic monsoon clouds hydro power generation by Sadananda Mohapatra posted 7/18/2012 on the Business Standard).

Hydro power generation in the state may decline over the next couple of weeks due to erratic and deficient monsoon…

Daily generation from seven hydro power plants in the state reached up to 722 MW this week, up from 210 MW in early June. However, as the monsoon rainfall has been below normal so far, power managers feel this could hurt generation in coming days.

“All reservoirs, except Burla, have water levels below or at par with (MDDL) Minimum Draw Down Level. The generations had gone up on expectation of better rainfall, but it has to come down as rainfall has not been satisfactory,” said a senior official of state-run power trader Gridco…

Even though hydro power generation does not contribute significantly to meet the state’s power demand, cash-strapped Gridco depends on it heavily due to its low cost and easier availability. This summer, thermal units operating in the state had to shut down operations frequently due to technical glitch or coal supply problems, compelling the power trader to look for other sources such as captive power plants.

Fossil fuel-fired plants may not be as clean as the renewable energies but they are more reliable.  With capacity factors in excess of 90%.  As long as they aren’t broke.  Or run out of fuel.  Things we can minimize with proper maintenance.  And a sound energy policy.  One that encourages the extraction of fossil fuels from the ground.  Even with this though these plants can go off line because they only have a CF of about 90%.  And sometimes that 10% happens.

Of the renewable energies hydroelectric is the one with the most commercial potential.  A mix of coal and hydro can go a long way in meeting a nation’s energy needs.  One that normally works in India.  When the rains cooperate.  Which they sometimes don’t.  Which limits their capacity factor.  For if the water in the reservoir isn’t high enough it can’t spin those water turbines fast enough.  Or long enough.  And if it falls too low it may not even be able to enter the water inlets that feed those water turbines.  A prolonged dry spell could shut a hydro dam down completely.  Something you never have to worry about with coal.

Renewable energy can help.  But it just can’t replace fossil fuel-generated electric power.  For nothing is more reliable.  Which is a comforting fact when you head home after a tiring day at work.  Knowing that the electricity-provided creature comforts you so enjoy will be there waiting for you.  Thanks in large part to coal.  With the occasional assist from hydroelectric power.

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