Skip to comments.(Texas)Wind farms may have warming effect - research
Posted on 04/29/2012 11:01:35 PM PDT by DallasBiff
LONDON, April 29 (Reuters) - Large wind farms might have a warming effect on the local climate, research in the United States showed on Sunday, casting a shadow over the long-term sustainability of wind power.
Carbon dioxide and other greenhouse gases from burning fossil fuels contribute to global warming, which could lead to the melting of glaciers, sea level rise, ocean acidification, crop failure and other devastating effects, scientists say.
In a move to cut such emissions, many nations are moving towards cleaner energy sources such as wind power.
The world's wind farms last year had the capacity to produce 238 gigawatt of electricity at any one time. That was a 21 percent rise on 2010 and capacity is expected to reach nearly 500 gigawatt by the end of 2016 as more, and bigger, farms spring up, according to the Global Wind Energy Council.
Researchers at the State University of New York at Albany analysed the satellite data of areas around large wind farms in Texas, where four of the world's largest farms are located, over the period 2003 to 2011.
The results, published in the journal Nature Climate Change, showed a warming trend of up to 0.72 degrees Celsius per decade in areas over the farms, compared with nearby regions without the farms.
"We attribute this warming primarily to wind farms," the study said. The temperature change could be due to the effects of the energy expelled by farms and the movement and turbulence generated by turbine rotors, it said.
"These changes, if spatially large enough, may have noticeable impacts on local to regional weather and climate," the authors said.
(Excerpt) Read more at reuters.com ...
“Velocity is not an energy level” - no, velocity is kenetic energy - the energy of motion.
“Velocity gives potential energy” - potential energy is the energy “no motion”. A lifted weight has potential energy that will be given up as it falls to a lower level.
A molecule of air hitting a moving turbine blade is like a ball hitting an object that is moving away from the ball. The ball after impact will have a slower speed than before, and the object will have hibher higher speed. Energy is transferred from the ball to the car.
With a gas, velocity, or let’s say speed which does not have an associated direction, is thermodynamically equivalent to temperature.
Potential energy does not relate to an object temperature.
Velocity will not increase an object temperature any more than lifting an object above the floor.
All velocity measurements are relative to other objects. Velocity has no absolute and stand alone measurement like temperature has. They are not related the way temperature, volume and pressure are related for gases.
Maybe this related example will help explain it better.
Take a child’s pinwheel. Hold it in a 20 mph breeze. Now live it 20 mph in still air. The reaction and effect on the air are the same, very minor heating by friction. The velocity was only relative to the ground as to which was moving and not part of the interaction equation.
For what you claim to work would require “still” air to drop in temperature aa you move the pinwheel through it.
Sorry, move it 20 mph, not live it.
I’m typing on a phone with autocorrect and I missed that in the preview.
“For what you claim to work would require still air to drop in temperature aa you move the pinwheel through it.”
Not true, because since you’re moving the pinwheel through the air (assuming it’s not freewheeling and therefore having no effect on the air), the pinwheel blades are speeding up the air molecules. By ‘speeding up’ I mean the molecules are moving faster coming out of the blades than going into the blades.
So the temperature of the air coming out of the blades is higher than the temperature going into the blades. This is the case when the blades are moved through the air, as opposed to the air moving against stationary blades.
When moving air is deflected by stationary blades, the air is slowed down.
That's because you didn't finance them with Rick Perry's ETF slush fund money.
You believe a 20 mph wind blowing against a stationary pinwheel would have a different effect than still air and a pinwheel held out the window of the car traveling 20 mph?
“20 mph wind ... pinwheel”
Forget my last post which was wrong.
Either way - pinwheel moving, air stationary or air moving, pinwheel stationary, the air is cooled because energy is taken from the air and converted to electricity (assuming the pinwheel is driving a generator).
I am sorry, but you have a different understanding of Physics than was taught when I go my engineering degree.
Have a nice day.
Is electrical energy produced? yes or no
Where does that energy come from? give your answer
If your answer is “from the moving air” then what is the difference between the air before going through the turbine and after it comes out of the turbine?
Momentum is reduced, not temperature.
If you won’t accept the difference between potential energy, and absolute energy values, or that velocity is only a relative measurement, not an absolute measurement like tenperature, then I cannot explain it to you.
Velocity is similar to potential energy in height with gravity. If I raise a rock above the ground, I have supplied potential energy. But I did not raise the temperature of the rock by lifting, nor will it cool as it crutches what it lands upon.
Velocity is the same way. It has no measurement accept in creation to something else. Temperature is an absolute value and needs no reference frame. Think of throwing a ball or throwing a ball from a moving truck and the again thrown inside a moving truck. You cannot relate the velocity to the object’s tempature.
nor will it cool as it crushes what it lands...
Velocity is the same way. It has no measurement accept in relation to something else.
“won’t accept the difference”
Of course velocity is relative, and temperature has an absolute zero but in thermodynamics it’s differences in temperature that you deal with.
Now answer the questions I posed. Here are the first two:
Is electrical energy produced by the turbine?
Where does that energy come from?
Say as much as you want but make sure you answer the questions.
Yes electrical energy is produced by the transfer of momentum of the air to the rotational force on the turbine.
The only effects on temperature are the friction of the moving surfaces and the inefficiencies of the wind turbine equipment. Both of these produce heat.
There is no drop in temperature.
I have been referring to the energy in the moving mass as potential energy in relation to the still frame of reference of the windmill.
A better term is kinetic energy. Momentum is the mass times the velocity. Work is the mass times acceleration (deceleration of the wind mass). Kinetic energy is 1/2 the mass times the velocity squared.
When the wind strikes the turbine blades, the momentum of the collision must remain the same. In reality it is less of a collision and more of a sliding pull. But the result is a slight slowing of the air flow. Momentum is transferred from the air to the rotating blades. The slowing of the wind is a reduction of the air’s kinetic energy. This kinetic energy is the source electrical power transferred through the blades, rotor and generator. Each of those devices have some degree of inefficiency and each one generates heat due to the inefficiencies like friction.
There is no cooling, only heating and transfer of kinetic energy to electrical energy.
Forget momentum. Collisions don’t have momentum. The sum of the momentums of two particles that elastically collide remains the same after the collision. Nothing about energy here.
The energy of each molecule is proportional to the square of its velocity. Slow it down and it gives up energy, and the law of conservation of energy says the energy goes somewhere.
In a gas, molecular motion is its energy. The energy is felt as wind and heat. Wind is a net motion in some direction. Heat is random motion.
In our discussions we’re talking about a gas that’s at a constant pressure.
I am sorry but are simply making things up and ignoring basic physics. This has become a conversation of you claiming red is really blue.
I don’t care to find new ways to explain the same thing over and over.
Have a nice day.