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Carnot Cycle
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What is the Carnot Cycle?

The Carnot Cycle has been described as being the most efficient thermal cycle possible, wherein there are no heat losses, and consisting of four reversible processes; two isothermal and two adiabatic. 

The Carnot Cycle has also been described as a cycle of expansion and compression of a reversible heat engine that does work with no loss of heat.

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Cogeneration Technologies
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The Renewable Energy Institute

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History of the Brayton Cycle,  Carnot Cycle,  Cheng Cycle,
Kalina Cycle,  Organic Rankine Cycle,  Rankine Cycle 
and Waste Heat Recovery

What is the Brayton Cycle?

Gas turbines operate on the principal of the Brayton Cycle, which is defined as a constant pressure cycle, with four basic operations which it accomplishes simultaneously and continuously for an uninterrupted flow of power.

Background Information and History of Rudolph Diesel and Sadi Carnot

Rudolph Diesel was educated at the predecessor school to the Technical University of Munich, Germany. In 1878, he was introduced to the work of Sadi Carnot, who theorized that an engine could achieve much higher efficiency than the steam engines of the day. Carnot envisioned a cycle in which a gas is compressed, heated, allowed to expand, and then cooled. After the gas is cooled, the cycle begins anew. Mechanical energy is used to compress the gas and thermal energy to heat it. In turn, expansion of the gas yields mechanical energy, and its cooling yields thermal energy. The net result is conversion of thermal energy to mechanical energy.

Diesel sought to apply Carnot’s theory to the internal combustion engine. The efficiency of the Carnot Cycle increases with the compression ratio—the ratio of gas volume at full expansion to its volume at full compression. Nicklaus Otto invented an internal combustion engine in 1876 that was the predecessor to the modern gasoline engine. Otto’s engine mixed fuel and air before their introduction to the cylinder, and a flame or spark was used to ignite the fuel-air mixture at the appropriate time. However, air gets hotter as it is compressed, and if the compression ratio is too high, the heat of compression will ignite the fuel prematurely. The low compression ratios needed to prevent premature ignition of the fuel-air mixture limited the efficiency of the Otto engine.

Rudolph Diesel wanted to build an engine with the highest possible compression ratio. He introduced fuel only when combustion was desired and allowed the fuel to ignite on its own in the hot compressed air. Diesel’s engine achieved an efficiency higher than that of the Otto engine and much higher than that of the steam engine. It also eliminated the trouble-prone electric-spark ignition system. Diesel received a patent in 1893 and demonstrated a workable engine in 1897. Today, diesel engines are classified as “compression-ignition” engines, and Otto engines are classified as “spark-ignition” engines.

What is the Kalina Cycle?

Invented by Alexander Kalina, a Russian engineer, the Kalina Cycle uses a water and ammonia in low temperature Waste Heat Recovery applications, such as geothermal power plants, to increase thermodynamic efficiency and power output. 

Problems associated with Kalina Cycle, and why it has never gained significant appeal include;

• GE Power attempted to operate a Kalina Cycle power plant in conjunction with a gas fired power plant but found it neither economical or competitive.

• Inability to operate efficiently at high temperature or high pressure.

• Nitriding of the alloy steel superheater tubes.

• Complicated distillation columns required to recombine the turbine exhaust into the binary mixture used in the heat exchangers
  

• cycle proposals seem to be based on zero frictional pressure drop and zero temperature differences in the main process components, and it is pretty expensive to meet such requirements.

some of the above information on the Kalina Cycle from www.eng-tips.com with our thanks.

What is the Organic Rankine Cycle?

A Rankine Cycle is a closed circuit steam cycle. (Also - see Rankine Cycle). 

An Organic Rankine Cycle uses a heated chemical instead of steam as found in the Rankine Cycle. 

Chemicals used in the Organic Rankine Cycle include freon, butane, propane, ammonia, and the new environmentally-friendly" refrigerants. 


Why use a chemical refrigerant? 

A refrigerant boils at a temperature below the temperature of frozen ice. Solar heat, for example, of only 150 degrees Fahrenheit from a typical rooftop solar hot water heater, will furiously boil a refrigerant. The resulting high-pressure refrigerant vapor is then piped to an organic Rankine Cycle engine. 


Why is it called "organic"? 

"Organic" is a term used in chemistry to describe a class of chemicals that includes Freon and most of the other common refrigerants.

What is the Rankine Cycle?

The Rankine Cycle is a thermodynamic cycle used to generate electricity in many power stations, and is the real-world approach to the Carnot Cycle. Superheated steam is generated in a boiler, and then expanded in a steam turbine. The steam turbine drives a generator, to convert the work into electricity. The remaining steam is then condensed and recycled as feed-water to the boiler. A disadvantage of using the water-steam mixture is that superheated steam has to be used, otherwise the moisture content after expansion might be too high, which would erode the turbine blades.

What is Waste Heat Recovery?

Many processes, especially in industrial applications, produce large amounts of excess heat – i.e., heat beyond what can be efficiently used in the process.  Waste Heat Recovery methods attempt to extract some of the energy as work that otherwise would be wasted.  

Typical methods of recovering heat in industrial applications include direct heat recovery to the process itself, recuperators, regenerators, and waste heat boilers.  In many applications – especially those with low-temperature waste heat streams, such as automotive applications – the economic benefits of waste heat recovery do not justify the cost of the recovery systems.  Innovative, affordable methods that are highly efficient, applicable to low-temperature streams, and/or suitable for use with corrosive or “dirty” wastes could expand the number of viable applications of waste heat recovery, as well as improve the performance of existing applications.  Our focus is on the development of innovative Waste Heat Recovery processes and techniques that are (1) more efficient than conventional methods, yet still cost-effective; and (2) applicable to waste streams from which heat cannot be recovered easily with conventional methods.

Turning to cooling, air conditioning systems consume approximately 10% of the energy used in U.S. buildings and are key contributors to peak demand.  Consequently, improving the energy efficiency of air conditioning systems would substantially reduce overall energy consumption and enhance grid reliability.  For example, compressors require cooling to dissipate the heat produced during compression and could benefit from improved surface heat transfer – innovative designs could increase the available heat-transfer area or materials enhancement could increase the heat flux between the hot and cool sides of a heat exchanger.  Similarly, a reduction in the requirement for condenser cooling could provide significant energy savings if more-efficient, cost-effective technologies were developed.  

This is where we believe waste heat recovery integrated with our Solar Trigeneration energy systems represents a unique opportunity for commercial and industrial clients. 

Industrial Waste Heat Recovery

Waste Heat Recovery from exit gases can significantly increase the energy efficiency of industrial processes.  Energy can be recovered from flue and stack gases, vent gases, and combustion gases at a variety of temperatures at large-scale industrial plants (chemical plants, petroleum refineries, biorefineries, pulp and paper mills, etc.).

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How we make and distribute electricity is changing! 

The electric power generation, transmission and distribution system (the electric "grid") is changing and evolving from the electric grid of the 19th and 20th centuries, which was inefficient, highly-polluting, very expensive and “dumb.”  

The "old" way of generating and distributing energy resembles this slide:

Hubbert's Peak Oil Predictions Now Proving True?

Marion King Hubbert was a geologist and scientist who worked at Shell Oil company's research lab in Houston, Texas.  Hubbert made several important contributions to geology, geophysics and petroleum geology.  Hubbert is most recognized for the "Hubbert Curve" and " Hubbert Peak Theory" which is now referred to as " Peak Oil. 

Hubbert's life work determined that the world has a finite amount of petroleum that can be produced.  (Similarly, there is a finite amount of coal.) Many scientists and engineers believe we have reached Hubbert's "peak oil" limit.  Hubbert's espouses that when 50% of domestic crude oil production has been reached, that there will be such significant upward demand on prices of the limited supplies of oil production, that the U.S. economy will experience severe economic, social, and political turmoil.

Hubbert's Peak Oil predictions have proven to be true and this is validated as the U.S. in the early 1970's produced about 60% of its' oil demand and imported 40%.  That equation has flipped since then, because our domestic oil production has been on the decline since 1970, so now, due to our declining domestic oil production, we have to import 60% of our oil supplies, to meet our country's oil/energy demands.

The Next Oil Shock Could be the "mother" of All Oil Shocks

How severe our economic calamity and next "oil shock" will depend upon a number of factors, including when this occurs, as well as the following:

1.  the dependence of the individual country upon its own crude oil production to meet its energy needs and to subsidize consumer imports; 

2.  the rate of relative decline in crude oil production; 

3.  the degree of difficulty encountered in replacing missing energy inputs; 

4.  the degree to which our country had prepared in advance for this inevitable geological and economic calamity.

Examples of past "oil shocks" and the economic and political calamities that followed:

United States: Our peak crude oil production of domestic oil occurred in 1970; the first "oil shock" and oil crisis followed in 1973 with the Arab/OPEC Oil Embargo.

Iran: Their peak crude oil production occurred in 1974; They had their islamic revolution 1979 that overturned government and replaced it with radical islam.

Soviet Union: Their peak crude oil production was in 1989; what happened next? 
Their country disintegrated and the collapse of the Soviet Union followed in 1991. 

Indonesia: Their peak crude oil production was in 1991; their financial and government crisis followed in 1997.

Iraq: Iraq's crude oil production was in 1989; they then invaded Kuwait (for their oil) in 1991.

Using Mr. Hubbert's predictions, that beginning around 2000  we would see peak (global) oil production, then, if the country's not weaning themselves off of their oil addiction, and had not begun making the switch to renewable energy, that the negative economic and political calamities would soon follow, including ever-increasing prices of energy that is from fossil fuels. 

Now is the time to begin weaning ourselves off of fossil fuels and making the transition to and increasing the use of renewable energy. If you don't believe in climate change, or global warming, GREAT! Join us in the switch to renewable energy and a fossil-free economy!

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America's Clear and Present Danger

America Has INCREASED its' Dependence on Foreign 
Sources of Energy by 50% Since 1973.

America is even more "addicted" to foreign oil today, than we were in 1973 - 1974 when OPEC, Saudi Arabia and other suppliers from the Middle-East  stopped selling us their fossil fuels, and created a significant blow to our economy.

According to Monty Goodell, Founder and Chairman of the Renewable Energy Institute, "our increased dependence and reliance on foreign energy supplies represents a Clear and Present Danger to our national security, our economy, and the lives and livelihood of every American. Energy - including the energy we use from imported fossil fuels, is the very "lifeblood" of the American economy as it is for every industrialized country.  An economy dies without it's lifeblood of energy. This Clear and Present Danger we face is far more serious than the problems related to greenhouse gas emissions.  And while greenhouse gas emissions are very serious issue, in the long-term, pales in comparison to America's vital national security interests and America's economic stability in the short term.  For this reason alone, America needs to transition away from its addiction to foreign energy supplies. And America's abundant renewable energy resources such as the energy we receive from the sun, and renewable energy technologies such as concentrated solar power (CSP) plants - can supply 100% of America's power requirements with a concentrating solar power plant measuring 75 miles by 75 miles, located in the Southwest U.S.  By generating America's power from concentrating solar power plants, America resolves its' short-term Clear and Present Danger as it relates to importing its energy from foreign countries, and the long-term problems relating to greenhouse gas emissions."

Continuing, Mr. Goodell states that "too many Americans have forgotten what happened to us in 1973, when the Arabs and OPEC brought the United States economy to a screeching halt during the OPEC Oil Embargo.  This happened because they (mainly the country of Saudi Arabia) disagreed with our foreign policy and is the reason why they "turned off the tap" of our need for their oil supplies. When Saudi Arabia and OPEC stopped the vital flow of oil to our country in 1973, they caused an "oil shock" that severely and negatively impacted our economy. 

Mr. Goodell's question for us to ponder is, "do these countries who sell us 60% of our daily energy requirements, like us and our foreign policy, or might they leverage our addiction to their fossil fuels, and turn off the tap to make us adjust or revise our foreign policy??  Like any addict, America's foreign policy may be held hostage to its addiction, and in this case, our addiction to foreign oil, may over-ride our national interests."

Have American's forgotten the gas shortages and long lines at 
their gas stations to get gas during the Arab Oil Embargo of 1973? 

"Apparently so."  Mr. Goodell states that "in 1973, America was 'addicted' and 'over the barrel' of foreign oil to the amount of 40%.  Forty percent of our energy 'needs' in 1973 came from countries - many of which didn't like us then, and I'm afraid, many of them still don't.  The difference between 1973 and today - is that today we receive 50% MORE foreign oil now than we did in 1973.  And now we know about the problems relating to greenhouse gas emissions that we didn't know then.  America needs to change course, and change course now, in terms of its' energy supplies and how we keep America's economy strong, without the threat of being held hostage to a middle-east tyrant or regime, that could once again, turn on us, and turn off our supply of foreign oil." 

Remember ????

" Sadly," Monty Goodell continues, " most Americans have forgotten the long lines of people waiting in their cars - lined up and waiting for gasoline at their nearby gas station, with lines that were many blocks long.  And, after waiting 4-5 hours, many even waiting overnight in many places, to finally take their turn to fill up their car with gasoline, only to find that the gas station had run out of gas."

"Let me Repeat.... That was 1973 when we imported 40% of our daily energy requirements in the form of crude oil from overseas, and from foreign countries - and many of these from countries that don't like us.

Today, over 35 years later, America has yet to learn the lesson.  We cannot continue our reliance on energy from foreign countries that supply us with 60% of the crude oil that our refineries use as a feedstock for producing gasoline and diesel fuel for our cars and trucks comes from overseas. 

America is "over the barrel" and it's not our barrel, but the barrels of oil that we are addicted by and owned by other countries.  Why have we not learned the lessons we needed to learn in 1973 when we were cut-off from the vital energy supplies we need? 

Countries like China, are growing rapidly, and have an insatiable need for crude oil. China, with their booming economy, is increasingly growing in its clout and control over international supplies of crude oil - whether they do this through their ability to buy as much oil as they need on a daily basis, or whether they simply but American drilling rigs, technology, and explore and produce oil and gas from their own fields. China, is buying large amounts of oil for their country, and causing upward pricing on declining supplies. What happens if Russia, with all of their oil and natural gas, along with China and Venezuela, with or without the help of OPEC, decided to NOT sell oil to us????

To be sure, greenhouse gas emissions are a problem, and to some, greenhouse gas emissions are also a Clear and Present Danger, but not to the extent that it presents an imminent Clear and Present Danger. 

America's reliance for 60% of our energy "needs" coming from foreign suppliers is un-acceptable.

The "driver" to get America to begin reducing and eliminating fossil fuel use should be our nation's national security and the welfare and safety of its citizens. And this can all begin with developing and investing in our own renewable energy resources and renewable energy technologies, let's start by putting solar on every rooftop that has a clear and unobstructed view of the Southern sky. See www.RooftopPV.com  or  www.DistributedPV.com  for more information.  Let's create incentives begin with adopting a national "Feed In Tariff" as Germany did in 1990. 

America, we simply do NOT have the luxury of time on our hands.  We need to end our dependence and reliance on foreign fossil fuels, especially from countries that don't like us! We need to rapidly begin expanding renewable energy resources and renewable energy technologies from our vast and abundant renewable energy resources, such as; solar, solar energy systems, solar cogeneration, solar trigeneration, "solar on every roof," waste to energy, waste to fuel, biomass gasification, B100 Biodiesel, Biomethane, Synthesis Gas, geothermal, E100 Ethanol (from sugar cane and NOT from corn), and wind, where it makes economic sense."   

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