Electricity, Heat Engine, Superheated Dry Steam, Coal-Fired Power Plant, Geothermal Power Plant and Waste-to-Energy Plant

Posted by PITHOCRATES - November 7th, 2012

Technology 101

(Originally published August 1, 2012)

Geothermal Power Plants and Waste-to-Energy Plants each produce less than Half of 1% of our Electricity

We produce the majority of our electricity with heat engines.  Where we boil water into steam to spin a turbine.  Or use the expanding gases of combustion to spin a turbine.  The primary heat engines we use are coal-fired power plants, natural gas-power plants and nuclear power plants.  The next big source of electricity generation is hydroelectric.  A renewable energy source.  In 2011 it produced less than 8% of our electricity.  These sources combined produce in excess of 95% of all electricity.  While renewable energy sources (other than hydroelectric) make up a very small percentage of the total.  Wind power comes in under 3%.  And solar comes in at less than 0.2% of the total.  So we are a very long way from abandoning coal, natural gas and nuclear power.

Two other renewable energy sources appear to hold promise.  Two heat engines.  One powered by geothermal energy in the earth.  The other by burning our garbage.  In a waste-to-energy plant.  These appear attractive.  Geothermal power appears to be as clean as it gets.  For this heat isn’t man-made.  It’s planet-made.  And it’s just there for the taking.  But the taking of it gets a little complicated.  As is burning our trash.  Not to mention the fact that few people want trash incinerators in their neighborhoods.  For these reasons they each provide a very small percentage of the total electric power we produce.  Both coming in at less than half of 1%.

So why steam?  Why is it that we make so much of our electrical power by boiling water?  Because of the different states of matter.  Matter can be a solid, liquid or a gas.  And generally passes from one state to another in that order.  Although there are exceptions.  Such as dry ice that skips the liquid phase.  It sublimates from a solid directly into a gas.  And goes from a gas to a solid by deposition.  Water, though, follows the general rule.  Ice melts into water at 32 degrees Fahrenheit (or 0 degrees Celsius).  Or water freezes into ice at the same temperature.  Water vaporizes into steam at 212 degrees Fahrenheit (or 100 degrees Celsius).  Or steam condenses into water at the same temperature.  These changes in the state of matter are easy to produce.  At temperatures that we can easily attain.  Water is readily available to vaporize into steam.  It’s safe and easy to handle.  Making it the liquid of choice in a heat engine.

Today’s Coal-Fired Power Plant pulverizes Coal into a Dust and Blows it into the Firebox

A given amount of water will increase about 1600 times in volume when converted to steam.  It’s this expansion that we put to work.  It’s what pushed pistons in steam engines.  It’s what drove steam locomotives.  And it’s what spins the turbines in our power plants.  The plumes of steam you see is not steam, though.  What you see is water droplets in the steam.  Steam itself is an invisible gas.  And the hotter and drier (no water) it is the better.  For water droplets in steam will pit and wear the blades on a steam turbine.  Which is why the firebox of a coal-fired plant reaches temperatures up to 3,000 degrees Fahrenheit (about 1,650 degrees Celsius).  To superheat the steam.  And to use this heat elsewhere in the power plant such as preheating water entering the boiler.  So it takes less energy to vaporize it.

To get a fire that hot isn’t easy.  And you don’t get it by shoveling coal into the fire box.  Today’s coal-fired power plant pulverizes coal into a dust and blows it into the firebox.  Because small particles can burn easier and more completely than large chunks of coal.  As one fan blows in fuel another blows in air.  To help the fire burn hot.  The better and finer the fuel the better it burns.  The better the fuel burns the hotter the fire.  And the drier the steam it makes.  Which can spin a turbine with a minimum of wear.

In a geothermal power plant we pipe steam out of the ground to spin a turbine.  If it’s hot enough.  Unfortunately, there aren’t a lot of geothermal wells that produce superheated dry steam.  Which limits how many of these plants we can build.  And the steam that the planet produces is not as clean as what man produces.  Steam out of the earth can contain a lot of contaminants.  Requiring additional equipment to process these contaminants out.  We can use cooler geothermal wells that produce wet steam but they require additional equipment to remove the water from the steam.  The earth may produce heat reliably but not water.  When we pipe this steam away the wells can run dry.  So these plants require condensers to condense the used steam back into water so we can pump it back to the well.  A typical plant may have several wells piped to a common plant.  Requiring a lot of piping both for steam and condensate.  You put all this together and a geothermal plant is an expensive plant.  And it is a plant that we can build in few places.  Which explains why geothermal power makes less than half of 1% of our electricity.

We generate approximately 87% of our Electricity from Coal, Natural Gas and Nuclear Power

So these are some the problems with geothermal.  Burning trash has even more problems.  The biggest problem is that trash is a terrible fuel.  We pulverize coal into a dust and blow into the firebox.  This allows a hot and uniform fire.  Trash on the other hand contains wet mattresses, wet bags of grass, car batteries, newspapers and everything else you’ve ever thrown away.  And if you ever lit a campfire or a BBQ you know some things burn better than other things.  And wet things just don’t burn at all.  So some of this fuel entering the furnace can act like throwing water on a hot fire.  Which makes it difficult to maintain a hot and uniform fire.  They load fuel on a long, sloping grate that enters the furnace.  Mechanical agitators shake the trash down this grate slowly.  As the trash approaches the fire it heats up and dries out as much as possible before entering the fire.  Still the fire burns unevenly.  They try to keep the temperature above 1,000 degrees Fahrenheit (about 538 degrees Celsius) .  But they’re not always successful.

They can improve the quality of the fuel by processing it first.  Tearing open bags with machinery so people can hand pick through the trash.  They will remove things that won’t burn.  Then send what will burn to a shredder.  Chopping it up into smaller pieces.  This can help make for a more uniform burn.  But it adds a lot of cost.  So these plants tend to be expensive.  And nowhere as efficient as a coal-fired power plant (or nuclear power plant) in boiling water into superheated dry steam.  Also, raw trash tends to stink.  And no one really knows what’s in it when it burns.  Making people nervous about what comes out of their smoke stacks.  You add all of these things up and you see why less than half of 1% of our electricity comes from burning our trash.

This is why we generate approximately 87% of our electricity from coal, natural gas and nuclear power.  Coal and nuclear power can make some of the hottest and driest steam.  But making a hot fire or bringing a nuclear reactor on line takes time.  A lot of time.  So we use these as baseload power plants.  They generate the supply that meets the minimum demand.  Power that we use at all times.  Day or night.  Winter or summer.  They run 24/7 all year long.  Natural gas plants add to the baseload.  And handle peak demands over the baseload.  Because they don’t boil water they can come on line very quickly to pickup spikes in electrical demand.  Hydroelectric power shares this attribute, too.  As long as there is enough water in the reservoir to bring another generator on line.  The other 5% (wind, solar, geothermal, trash incinerators, etc.) is more of a novelty than serious power generation.

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Clean Renewable Energy leaves India Vulnerable to more Massive Power Blackouts

Posted by PITHOCRATES - August 25th, 2012

Week in Review

Hydroelectric power is the king of renewable energy.  The fuel is free.  It doesn’t burn.  It doesn’t pollute.  It’s quiet.  They can produce power when the sun doesn’t shine (unlike solar power).  And they can produce power when the wind doesn’t blow (unlike wind power).  Their reservoirs make scenic lakes and wildlife areas.  And after they’re built they don’t need a complicated infrastructure or masses of workers running around acres of land to keep them running.  They really only have one drawback.  You have no control over that free fuel (see More Power Blackouts Expected In India by Kenneth Rapoza posted 8/20/2012 on Forbes).

Between lackluster rainfall during monsoon season and a nasty political imbroglio in the capital city, India seems to be going back to the past.

And now, the northern states, including Delhi, could face power outages yet again as three small hydroelectric power stations have been shut down.  Combined, they run about 3,000 megawatts of electricity. Electricity generated at those power plants is distributed to 28 per cent of Indian households.

At the end of last month, back to back power outages gave way to power surges that unleashed quite a bit of chaos for over 600 million people affected.  In the last week of July, around 360 million people lost power in northern India due to excessive demand and a shortfall in hydropower. On July 31, power resumed in Delhi only to fail again the next day, with the chaos spreading to Calcutta and other parts of eastern India.

This is why reliable coal-fired power plants typically provide the majority of baseload power requirements.  The minimum amount of power we consistently use throughout the year.  Because a coal-fired power plant can also produce power when the sun doesn’t shine or when the wind doesn’t blow.  And they can even produce power when the monsoons don’t come.  You can call coal Mr. Reliable when it comes to power generation.  Old Faithful.  Mr. Dependable.  The Life Saver and Comfort Giver.  No matter the heat or humidity a coal-fired power plant will say, “Give me coal and I will keep your lights on and your air conditioners running.  In your homes.  In your hospitals.  In your restaurants.  Wherever you go.  Whatever your needs.  To help you back to good health.  Or so you can simply relax at the end of a hot, humid and exhausting day.  Give me coal and I will provide for you.”

But, alas, the government of India is trying to reduce India’s carbon footprint.  And is pursuing wind and solar power.  In fact they have just connected the world’s largest solar power plant to their electric grid.  Gujarat Solar Park.  Covering some 11 sites spread over 3,000 acres.  Putting some 600 megawatts onto the grid.  Replacing about 20% of what those three small hydroelectric dams were putting on the grid.  That is, the world’s largest solar power plant can only produce what three small hydroelectric dams can produce.  And that’s only when the sun shines.  An incredible investment of capital that did not prevent in any way the back to back massive power failures that left 360 million people without power.  Which is more than the entire population of the United States.  Which is about 314 million.  Just to give you an idea of how big this power failure was.

Just think what that massive investment in solar power could have done in the northern states of India.  Instead of tilting at windmills.  The global warming boogeyman.  They could have rebuilt the electric grid.  Added a coal-fired power plant or two.  And paid for who knows how much coal.  Had the Indian government done that the good people of India probably would not have suffered through back to back power outages.  Not with Mr. Reliable on the scene.  Who laughs at large power loads.  Because he can produce power every hour of every day of every season.  The way people like their power.

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India turns to Renewable Energy and Abandons Coal, causing one of the World’s Worst Power Outages

Posted by PITHOCRATES - August 5th, 2012

Week in Review

India suffered a massive power outage that left some 600 million Indians without power.  Stranding train travelers.  And trapping miners underground.  Not to mention leaving people to swelter in 100+ degree Fahrenheit temperatures.  In one of the most humid climates to ever grace our planet.  Some buildings had backup generators.  Including hospitals.  But these were few.   Most just suffered.  One wonders how this can happen in one of the biggest emerging economies.  India is, after all, one of the BRICS.  And being that the modern economy runs on energy it leaves one scratching their head.  If India has such a burgeoning economy where is their electricity production (see India: More than 600 million without power in biggest blackout ever by Rick Westhead posted 7/31/2012 on the Toronto Star)?

 While India has been aggressively trying to encourage investment in renewable energy sources such as solar and wind power, critics say it rarely upgrades its electrical grid. India has missed every annual target to add electricity production capacity since 1951, Bloomberg reported.

Oh.  They’ve been pouring millions into renewable energy to save the planet while they in essence have left their country plugged into the lamp post on the corner.  Here’s an interesting fact.  India just recently switched on the world’s largest solar photovoltaic power plant.  They are also a leader in wind power.  So they are working hard to remove their carbon footprint.  While their economy, and their people, starve for reliable electric power.  Let’s go to Bloomberg for more details (see Ambani, Tata ‘Islands’ Shrug Off Grid Collapse: Corporate India by Rajesh Kumar Singh and Rakteem Katakey posted 8/3/2012 on Bloomberg).

About 1.6 trillion rupees ($29 billion) spent by companies including Tata Motors and billionaire Mukesh Ambani-led Reliance Industries Ltd. (RIL), to quarantine their plants from the national grid is shielding India’s biggest users of electricity from disruptions. Sixty years of missed investment targets, transmission losses and theft is prompting factories to build their own plants boosting costs in a nation that suffers from the fastest pace of inflation among BRIC nations…

Five of India’s biggest electricity users generate 96 percent of their requirement, according to their annual reports.

India’s electric power is so unreliable that large consumers of electricity have to produce their own.  We call it captive power.    They generate it.  They keep it.  Which is only fair as they paid a fortune to generate it.  Which, of course, they pass on to their customers.  Via higher prices.  Which just adds to the inflation.

India has missed every capacity addition target since 1951, underscoring the urgency behind Singh’s effort to boost investment in power. As much as $300 billion, or 30 percent of the total spend planned on infrastructure, over the next five years is on the electricity sector, according to Planning Commission Member B.K. Chaturvedi.

The network in Asia’s third-largest economy loses 27 percent of the power it carries through dissipation from wires and theft, while peak supply falls short of demand by an average of 9 percent, according to India’s Central Electricity Authority. Some 300 million people in India, or one in every four, remain without links to the grid and the number will still be about 150 million by 2030, according to the Paris-based International Energy Agency.

The blackout engulfed as many as 19 of the South Asian country’s 28 states on July 31, with more than 100 intercity trains stranded on the second day…

They have been failing to meet demand since 1951?  Wow.  What a horrible track record.  Yet they can build the world’s largest solar photovoltaic power plant.  Even though their electric grid can’t transmit the insufficient power that they can produce.  And what’s astonishing is one in every four people doesn’t even have electricity.  This in one of the strongest emerging economies.  A country that is capable of doing so much better.  Full of people deserving so much better.  But they leave the electric grid to the elements.  While they spend a fortune to build the world’s largest solar photovoltaic power plant.  That can only “power a medium-sized city’s worth of homes.”  What a catastrophic misuse of investment capital.  No wonder large consumers of electricity are building their own generating capacity.

Companies plan to set up more than 33,000 megawatts of new captive power capacity and applications for approvals are pending with various state agencies, Rajiv Agrawal, New Delhi- based secretary of the power producers’ lobby said on Aug. 2. Some of these stations may not be set up because of a shortage of coal supplies, he said…

The pace of growth in generation has failed to keep up with demand because of a shortage in coal and natural gas supply, and deficient monsoon rains.

The world’s second-most populous nation suffers from frequent power outages that can last as long as 10 hours, amid summer temperatures of as high as 45 degrees Celsius (113 degrees Fahrenheit) in the capital, New Delhi. Power supply shortages shave about 1.2 percentage points off the nation’s annual growth, according to the Planning Commission…

This is what happens when you demonize one of the most energy-rich and reliable fuels.  Coal.  To reduce your carbon footprint.  Saving the planet may come at the cost of killing people.  Forcing people in an advanced society powered by electricity to go without electricity frequently.  Coal-fired power plants are the backbone of baseload power.  Those plants that run 24/7 to produce a steady stream of power to meet most of our needs.  These efficient heat engines can spin steam turbines forever as long as we feed them coal.  And a large coal-fired power plant can power everything in a region full of large cities.  Not just the homes in a medium city.

Subsidized electricity to farmers is also exacerbating electricity-supply bottlenecks, discouraging producers from adding capacity. India deliberately abandoned metering power supply for agricultural irrigation in the 1970s, as part of a strategy of switching to new high-yield crops, which required regular water supplies, Miriam Golden of the University of California and Brian Min of the University of Michigan said in a report published in April…

The Reserve Bank of India refrained from raising its benchmark interest rate on July 31 amid the slowest pace of growth in almost a decade and raised its inflation forecast to 7 percent from 6.5 percent, citing rising food prices and lack of roads, ports and power plants…

A dry monsoon season is a double whammy.  The lack of rain has lowered levels in the reservoirs at hydroelectric dams.  Reducing the amount of power they can produce.  On top of that the dry weather has forced farmers to irrigate their lands.  Using free electricity.  Which doesn’t discourage them in any way from sucking power off the grid.  Adding to the strain of the grid.  Doing their part in causing power outages.  Adding to inflationary pressures.  And loss in GDP.

This is a horrendous energy policy.  But you know who would approve of it?  President Obama.  For he is trying to do the same thing in America.  Shutter the coal industry and replace it with renewable energy.  He’s even cool on nuclear power.  Which is something the Indians are planning to expand to meet their exploding electrical demand.  Nuclear power.  So their horrendous energy policy is bad.  But it’s still a bit more sensible in one area.  They aren’t trying to shutter nuclear power, too.  Which happens to be one of the other most energy-rich and reliable fuels.  Joining coal to provide the backbone of baseload power.  Where a government will have it, that is.

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France uses Renewable Energy to offset a Decline in Nuclear Power Generated Electricity

Posted by PITHOCRATES - August 4th, 2012

Week in Review

France may be moving ahead in renewable energies but they are only a sideshow to the major electricity producer.  Nuclear power.  In the grand scheme of things there is only one renewable energy that is a serious player.  Hydroelectric power.  Which is picking up the slack during some planned outages at their nuke plants (see French utility EDF sees profit up 4.6 percent as renewable energy offsets lower nuclear output by Associated Press posted 7/31/2012 on The Washington Post).

Electricite de France saw profits rise 4.6 percent in the first half of the year as growth in renewable energy offset lower nuclear output…

The increase in profits and sales came despite more planned outages at nuclear plants — and also unexpected extensions of those outages — this year than last. The company’s chief financial officer Thomas Piquemal said those issues should be resolved by August.

Hydropower, which struggled last year, and other renewable energies made up the difference. Excluding one-off charges, the group’s net income grew 10.3 percent.

Executives said that the group’s better-than-expected results were also due to a reduction in costs.

One would almost get the impression that the French, too, are abandoning nuclear power in favor of renewable energy sources.  To save the planet.  Well, they are pursuing renewable energy sources.  But they’re not abandoning nuclear power.  Because they can’t.  Taking a look at French electricity production explains why.  (These numbers are pulled from Table 6 in The French wholesale electricity, natural gas and CO2 markets in 2010-2011 and Part V in THE FREN CH ELECTRICITY REPORT 2010).

(Note: The variation is in electricity produced.)

Nuclear power produces the majority of French electricity.  About three-quarters of it.  And they were increasing their nuclear capacity in 2010.  And of all their electricity sources nuclear power is operating nearest full capacity.  Of all the nuclear reactor capacity they installed 74% is producing electricity.

The next largest producer of electricity is hydroelectric power.  And it only produces 12.4% of all electricity.  Of all the generating capacity of hydroelectric power only 31% actually produced electricity.  So more than two thirds of hydroelectric dam capacity sat idle.  Hydroelectric power increased 9.9% in 2010 “as a result of changes in the availability of water resources and the use of reservoirs” according the French Electricity Report.  Which means hydroelectric power is only as good as the volume of water behind those dams.  And once they build those dams it’s up to the weather to snow in the winter (in places that have winters with snowfall) and rain in the the spring, summer and fall.  With more than two-thirds of installed capacity sitting idle either it hasn’t rained or snowed enough in the mountains.  Or that water is being diverted for other uses.

The next largest producer of electricity is natural gas producing 5.5% of the total.  Because of the speed they can bring a gas turbine on line we often use these to handle peaks in demand.  So they don’t run all of the time like the nuclear power plants that provide the baseload.  Based on these numbers the baseload handled the electrical demand most of the time as these gas turbines only produced at 42% of their installed capacity.

After natural gas comes coal at 3.5% of the total.  A 7.6% drop from the previous year.  With 72% of installed capacity sitting idle.  A basic shuttering of the coal industry to make way for renewable energy.

Wind power produced 1.7% of all electricity.  An increase of 22.2% from the previous year.  So they’re increasing wind power.  But it’s almost statistically insignificant.  Worse, of the installed capacity only 24% is producing electricity.  That’s because they can only produce electricity when the wind blows.  But not too fast.  Or too slow.  Only a narrow band of wind speeds can produce electricity at the same frequency (typically 50 Hertz in Europe) that matches the grid.

And solar power produced a statistically insignificant 0.1% of the electricity total.  And this is a 281.6% increase over the previous year.  But of the total installed capacity only 34% of it produced electricity.  Because it is sometimes night.  And sometimes cloudy.  Which is why it will be difficult to get a large percentage of our electricity from solar power.  The fuel may be free.  But it’s just not always there.  Also, photocells are semiconductor devices that produced low DC currents.  So you need a lot of solar arrays to produce useable power.  And additional electrical equipment to convert the DC power into AC power.  And more if you want to store power during the day to use at night.  So even though the fuel is free solar power can be very expensive.

So nuclear power isn’t going anywhere in France.  It’s too reliable.  And it’s just too prevalent.  To replace that capacity would require enormous amounts of money.  Which just isn’t that prevalent during a European sovereign debt crisis.

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Electricity, Heat Engine, Superheated Dry Steam, Coal-Fired Power Plant, Geothermal Power Plant and Waste-to-Energy Plant

Posted by PITHOCRATES - August 1st, 2012

Technology 101

Geothermal Power Plants and Waste-to-Energy Plants each produce less than Half of 1% of our Electricity

We produce the majority of our electricity with heat engines.  Where we boil water into steam to spin a turbine.  Or use the expanding gases of combustion to spin a turbine.  The primary heat engines we use are coal-fired power plants, natural gas-power plants and nuclear power plants.  The next big source of electricity generation is hydroelectric.  A renewable energy source.  In 2011 it produced less than 8% of our electricity.  These sources combined produce in excess of 95% of all electricity.  While renewable energy sources (other than hydroelectric) make up a very small percentage of the total.  Wind power comes in under 3%.  And solar comes in at less than 0.2% of the total.  So we are a very long way from abandoning coal, natural gas and nuclear power.

Two other renewable energy sources appear to hold promise.  Two heat engines.  One powered by geothermal energy in the earth.  The other by burning our garbage.  In a waste-to-energy plant.  These appear attractive.  Geothermal power appears to be as clean as it gets.  For this heat isn’t man-made.  It’s planet-made.  And it’s just there for the taking.  But the taking of it gets a little complicated.  As is burning our trash.  Not to mention the fact that few people want trash incinerators in their neighborhoods.  For these reasons they each provide a very small percentage of the total electric power we produce.  Both coming in at less than half of 1%.

So why steam?  Why is it that we make so much of our electrical power by boiling water?  Because of the different states of matter.  Matter can be a solid, liquid or a gas.  And generally passes from one state to another in that order.  Although there are exceptions.  Such as dry ice that skips the liquid phase.  It sublimates from a solid directly into a gas.  And goes from a gas to a solid by deposition.  Water, though, follows the general rule.  Ice melts into water at 32 degrees Fahrenheit (or 0 degrees Celsius).  Or water freezes into ice at the same temperature.  Water vaporizes into steam at 212 degrees Fahrenheit (or 100 degrees Celsius).  Or steam condenses into water at the same temperature.  These changes in the state of matter are easy to produce.  At temperatures that we can easily attain.  Water is readily available to vaporize into steam.  It’s safe and easy to handle.  Making it the liquid of choice in a heat engine.

Today’s Coal-Fired Power Plant pulverizes Coal into a Dust and Blows it into the Firebox

A given amount of water will increase about 1600 times in volume when converted to steam.  It’s this expansion that we put to work.  It’s what pushed pistons in steam engines.  It’s what drove steam locomotives.  And it’s what spins the turbines in our power plants.  The plumes of steam you see is not steam, though.  What you see is water droplets in the steam.  Steam itself is an invisible gas.  And the hotter and drier (no water) it is the better.  For water droplets in steam will pit and wear the blades on a steam turbine.  Which is why the firebox of a coal-fired plant reaches temperatures up to 3,000 degrees Fahrenheit (about 1,650 degrees Celsius).  To superheat the steam.  And to use this heat elsewhere in the power plant such as preheating water entering the boiler.  So it takes less energy to vaporize it.

To get a fire that hot isn’t easy.  And you don’t get it by shoveling coal into the fire box.  Today’s coal-fired power plant pulverizes coal into a dust and blows it into the firebox.  Because small particles can burn easier and more completely than large chunks of coal.  As one fan blows in fuel another blows in air.  To help the fire burn hot.  The better and finer the fuel the better it burns.  The better the fuel burns the hotter the fire.  And the drier the steam it makes.  Which can spin a turbine with a minimum of wear.

In a geothermal power plant we pipe steam out of the ground to spin a turbine.  If it’s hot enough.  Unfortunately, there aren’t a lot of geothermal wells that produce superheated dry steam.  Which limits how many of these plants we can build.  And the steam that the planet produces is not as clean as what man produces.  Steam out of the earth can contain a lot of contaminants.  Requiring additional equipment to process these contaminants out.  We can use cooler geothermal wells that produce wet steam but they require additional equipment to remove the water from the steam.  The earth may produce heat reliably but not water.  When we pipe this steam away the wells can run dry.  So these plants require condensers to condense the used steam back into water so we can pump it back to the well.  A typical plant may have several wells piped to a common plant.  Requiring a lot of piping both for steam and condensate.  You put all this together and a geothermal plant is an expensive plant.  And it is a plant that we can build in few places.  Which explains why geothermal power makes less than half of 1% of our electricity.

We generate approximately 87% of our Electricity from Coal, Natural Gas and Nuclear Power

So these are some the problems with geothermal.  Burning trash has even more problems.  The biggest problem is that trash is a terrible fuel.  We pulverize coal into a dust and blow into the firebox.  This allows a hot and uniform fire.  Trash on the other hand contains wet mattresses, wet bags of grass, car batteries, newspapers and everything else you’ve ever thrown away.  And if you ever lit a campfire or a BBQ you know some things burn better than other things.  And wet things just don’t burn at all.  So some of this fuel entering the furnace can act like throwing water on a hot fire.  Which makes it difficult to maintain a hot and uniform fire.  They load fuel on a long, sloping grate that enters the furnace.  Mechanical agitators shake the trash down this grate slowly.  As the trash approaches the fire it heats up and dries out as much as possible before entering the fire.  Still the fire burns unevenly.  They try to keep the temperature above 1,000 degrees Fahrenheit (about 538 degrees Celsius) .  But they’re not always successful.

They can improve the quality of the fuel by processing it first.  Tearing open bags with machinery so people can hand pick through the trash.  They will remove things that won’t burn.  Then send what will burn to a shredder.  Chopping it up into smaller pieces.  This can help make for a more uniform burn.  But it adds a lot of cost.  So these plants tend to be expensive.  And nowhere as efficient as a coal-fired power plant (or nuclear power plant) in boiling water into superheated dry steam.  Also, raw trash tends to stink.  And no one really knows what’s in it when it burns.  Making people nervous about what comes out of their smoke stacks.  You add all of these things up and you see why less than half of 1% of our electricity comes from burning our trash.

This is why we generate approximately 87% of our electricity from coal, natural gas and nuclear power.  Coal and nuclear power can make some of the hottest and driest steam.  But making a hot fire or bringing a nuclear reactor on line takes time.  A lot of time.  So we use these as baseload power plants.  They generate the supply that meets the minimum demand.  Power that we use at all times.  Day or night.  Winter or summer.  They run 24/7 all year long.  Natural gas plants add to the baseload.  And handle peak demands over the baseload.  Because they don’t boil water they can come on line very quickly to pickup spikes in electrical demand.  Hydroelectric power shares this attribute, too.  As long as there is enough water in the reservoir to bring another generator on line.  The other 5% (wind, solar, geothermal, trash incinerators, etc.) is more of a novelty than serious power generation.

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Conservation of Energy, Potential Energy, Kinetic Energy, Waterwheels, Water Turbine, Niagara Falls, Dams, and Hydroelectric Power

Posted by PITHOCRATES - July 25th, 2012

Technology 101

Roller Coasters use Gravity to Convert Energy back and forth between Potential Energy and Kinetic Energy

We cannot destroy energy.  All we can do is convert it.  It’s a law of physics.  The law of conservation of energy.  A roller coaster shows this.  Where roller coasters move by converting potential energy into kinetic energy.  And then by converting kinetic energy back into potential energy.

The best roller coasters race down tall inclines gaining incredible speed.  The taller the coaster the faster the speed.  That’s because of potential energy (stated in units of joules).  Which is equal to the mass times the force of gravity times the height.  The last component is what makes tall roller coasters fast.  Height.  As the cars inch over the summit gravity begins pulling them down.  And the longer gravity can pull them down the more speed they can gain.  At the bottom of the hill the height is zero so the potential energy is zero.  All energy having been converted into kinetic energy (also stated in units of joules).

Roller coasters travel the fastest at the lowest points in the track.  Where potential energy equals zero.  While kinetic energy is at its highest.  Which is equal to one half times the mass times the velocity squared.  So the higher the track the more time gravity has to accelerate these cars.  At their fastest speed they start up the next incline.  Where the force of gravity begins to pull on them.  Slowing them down as they climb up the next hill.  Converting that kinetic energy back into potential energy.  When they crest the hill for a moment their speed is zero so their kinetic energy is zero.  All energy having been converted back into potential energy.  Where gravity tugs those cars down the next incline.  And so on up and down each successive hill.  Where at all times the sum of potential energy and kinetic energy equals the same amount of joules.  Maximum potential energy is at the top.  Maximum kinetic energy is at the bottom.  And somewhere in the middle they each equal half of their maximum amounts.

(This is a simplified explanation.  Additional forces are ignored for simplicity to illustrate the relation between potential energy and kinetic energy.)

We build Dams on Rivers  to do what Niagara Falls does Naturally

So once over the first hill roller coasters run only on gravity.  And the conversion of energy from potential to kinetic energy and back again.  Except for that first incline.  Where man-made power pulls the cars up.  Electric power.  Produced by generators.  Spun by kinetic energy.  Produced from the expanding gases of combustion in a natural gas-powered plant.  Or from high-pressure steam produced in a coal-fired power plant or nuclear power plant.  Or in another type of power plant that converts potential energy into kinetic energy.  In a hydroelectric dam.

Using water power dates back to our first civilizations.  Then we just used the kinetic energy of a moving stream to turn a waterwheel.  These waterwheels turned shafts and pulleys to transfer this power to work stations.  So they couldn’t spin too fast.  Which wasn’t a problem because people only used rivers and streams with moderate currents.  So these wheels didn’t spin fast.  But they could turn a mill stone.  Or run a sawmill.  With far more efficiency than people working with hand tools.  But there isn’t enough energy in a slow moving river or stream to produce electricity.  Which is why we built some of our first hydroelectric power plants at Niagara Falls.  Where there was a lot of water at a high elevation that fell to a lower elevation.  And if you stick a water turbine in the path of that water you can generate electricity.

Of course, there aren’t Niagara Falls all around the country.  Where nature made water fall from a high elevation to a low elevation.  So we had to step in to shape nature to do what Niagara Falls does naturally.  By building dams on rivers.  As we blocked the flow of water the water backed up behind the dam.  And the water level climbed up the river banks to from a large reservoir.  Or lake.  Raising the water level on one side of the dam much higher than the other side.  Creating a huge pool of potential energy (mass times gravity times height).  Just waiting to be converted into kinetic energy.  To drive a water turbine.  The higher the height of the water behind the dam (or the higher the head) the greater the potential energy.  And the greater the kinetic energy of the water flow.  When it flows.

Hydroelectric Power is the Cleanest and Most Reliable Source of Renewable Energy-Generated Power

Near the water level behind the dam are water inlets into channels through the dam or external penstocks (large pipes) that channels the water from the high elevation to the low elevation and into the vanes of the water turbine.  The water flows into these curved vanes which redirects this water flow down through the turbine.  Creating rotational motion that drives a generator.  After exiting the turbine the water discharges back into the river below the dam.

Our electricity is an alternating current at 60 hertz (or cycles per second).  These turbines, though, don’t spin at 60 revolutions per second.  So to create 60 hertz they have to use different generators than they use with steam turbines.  Steam turbines spin a generator with only one rotating magnetic field to induce a current in the stator (i.e., stationary) windings of the generator.  They can produce an alternating current at 60 hertz because the high pressure steam can spin these generators at 60 revolutions per second.  The water flowing through a turbine can’t.  So they add additional rotational magnetic fields in the generator.  Twelve rotational magnetic fields can produce 60 hertz of alternating current while the generator only spins at 5 revolutions per second.  Adjustable gates open and close to let more or less water to flow through the turbine to maintain a constant rotation.

The hydroelectric power plant is one of the simplest of power generating plants.  There is no fuel needed to generate heat to make steam.  No steam pressure to monitor closely to prevent explosions.  No fires to worry about in the mountains of coal stored at a plant.  No nuclear meltdown to worry about.  And no emissions.  All you need is water.  From snow in the winter that melts in the spring.  And rain.  Not to mention a good river to dam.  If the water comes the necessary head behind the dam will be there to spin those turbines.  But sometimes the water isn’t there.  And the dams have to shut down generators because there isn’t enough water.  But hydroelectric power is still the cleanest and most reliable source of electric power generated from renewable energy we have.  But it does have one serious drawback.  You need a river to dam.  And the best spots already have a dam on them.  Leaving little room for expansion of hydroelectric power.  Which is why we generate about half of our electric power from coal.  Because we can build a coal-fired power plant pretty much anywhere we want to.  And they will run whether or not we have snow or rain.  Because they are that reliable.

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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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