Vertical Wind Power Systems

Mark asks…

What happens to heat in an atmosphere when pressure is low?

Also what are factors that could affect pressure in the area

Windmill Farms answers:

When the pressure is low, then…

Extratropical cyclones form as waves along weather fronts due to a passing by shortwave aloft or upper level jet streak before occluding later in their life cycle as cold core cyclones.[13][14][15] [16] Polar lows are small-scale, short-lived atmospheric low-pressure systems that are found over the ocean areas poleward of the main polar front in both the Northern and Southern Hemispheres. They are part of the larger class of mesoscale weather systems. Polar lows can be difficult to detect using conventional weather reports and are a hazard to high-latitude operations, such as shipping and gas and oil platforms. They are vigorous systems that have near-surface winds of at least 17 metres per second (38 mph).[17]

Tropical cyclones form due to latent heat driven by significant thunderstorm activity, and are warm core with well-defined circulations.[18] Certain criteria need to be met for their formation. In most situations, water temperatures of at least 26.5 °C (79.7 °F) are needed down to a depth of at least 50 m (160 ft);[19] waters of this temperature cause the overlying atmosphere to be unstable enough to sustain convection and thunderstorms.[20] Another factor is rapid cooling with height, which allows the release of the heat of condensation that powers a tropical cyclone.[19] High humidity is needed, especially in the lower-to-mid troposphere; when there is a great deal of moisture in the atmosphere, conditions are more favorable for disturbances to develop.[19] Low amounts of wind shear are needed, as high shear is disruptive to the storm’s circulation.[19] Lastly, a formative tropical cyclone needs a pre-existing system of disturbed weather, although without a circulation no cyclonic development will take place.[19] Mesocyclones form as warm core cyclones over land, and can lead to tornado formation.[21] Waterspouts can also form from mesocyclones, but more often develop from environments of high instability and low vertical wind shear.[22]
In deserts, lack of ground and plant moisture that would normally provide evaporative cooling can lead to intense, rapid solar heating of the lower layers of air. The hot air is less dense than surrounding cooler air. This, combined with the rising of the hot air, results in a low-pressure area called a thermal low.[23] Monsoon circulations are caused by thermal lows which form over large areas of land and their strength is driven by how land heats quicker than the surrounding nearby ocean. This creates a steady wind blowing toward the land, bringing the moist near-surface air over the oceans with it.[24] Similar rainfall is caused by the moist ocean air being lifted upwards by mountains,[25] surface heating,[26] convergence at the surface,[27] divergence aloft, or from storm-produced outflows at the surface.[28] However the lifting occurs, the air cools due expansion in lower pressure, which in turn produces condensation. In winter, the land cools off quickly, but the ocean keeps the heat longer due to its higher specific heat. The hot air over the ocean rises, creating a low-pressure area and a breeze from land to ocean while a large area of drying high pressure is formed over the land, increased by wintertime cooling.[24] Monsoons are similar to sea and land breezes, a term usually referring to the localized, diurnal (daily) cycle of circulation near coastlines everywhere, but they are much larger in scale, stronger and seasonal.[29]

See: http://en.wikipedia.org/wiki/Low-pressure_area

Make note that this all depends on the type of climate and the setting! There is exactly no formula to determine the nature of heat when pressure is low.

Good luck!

Donald asks…

HELP ME. PHYSICS!!!!!!?

The good news .. your great aunt tilley just left you her farm since you were her favourite relative! The bad news .. the farm has not been modernized since 1867!!
Your mission now is to come up with a plan to make the farm self-sufficient in terms of electrical energy production.

About the farm:

The farm is primarily a dairy farm on 100 ha of south-sloping land. It has a good sized house, a large dairy barn with a milking parlour and two vertical silos. The land is mostly planted for pasture and hay. There is a fast-flowing stream running through the property. The region has an average annual wind speed of 12 km/h and approximately 65% of the days are sunny.

Answer the following.

1) Explain the difference between renewable and non-renewable resources of energy. Give two examples for each.

2) One of the ways to save energy is to replace outdated incadescent light bulbs with fluorescent bulbs. Research and suggest 4 other energy saving tips for this farm without comprimising lifestyle (eg: washing clothes by hand is a NO-NO!)

Windmill Farms answers:

Most of the energy stored in these wind movements can be found at high altitudes where continuous wind speeds of over 160 km/h (100 mph) occur.

Renewable energy is energy generated from natural resources—such as sunlight, wind, rain, tides and geothermal heat—which are renewable.
OR

“Renewable energy is derived from natural processes that are replenished constantly. In its various forms, it derives directly from the sun, or from heat generated deep within the earth. Included in the definition is electricity and heat generated from solar, wind, ocean, hydropower, biomass, geothermal resources, and biofuels and hydrogen derived from renewable resources.”

Explanations:
Wind power:
Airflows can be used to run wind turbines. Modern wind turbines range from around 600 kW to 5 MW of rated power, although turbines with rated output of 1.5–3 MW have become the most common for commercial use; the power output of a turbine is a function of the cube of the wind speed, so as wind speed increases, power output increases dramatically.Areas where winds are stronger and more constant, such as offshore and high altitude sites, are preferred locations for wind farms.

Since wind speed is not constant, a wind farm’s annual energy production is never as much as the sum of the generator nameplate ratings multiplied by the total hours in a year. The ratio of actual productivity in a year to this theoretical maximum is called the capacity factor. Typical capacity factors are 20-40%, with values at the upper end of the range in particularly favorable sites. For example, a 1 MW turbine with a capacity factor of 35% will only produce an average of 0.35 MW. Over a year, output would be .35x24x365 = 3,066 MWh instead of 24×365 = 8,760 MWh. Online data is available for some locations and the capacity factor can be calculated from the yearly output.

Water power:
Energy in water (in the form of kinetic energy, temperature differences or salinity gradients) can be harnessed and used. Since water is about 800 times denser than air,even a slow flowing stream of water, or moderate sea swell, can yield considerable amounts of energy.
There are many forms of water energy:

* Hydroelectric energy is a term usually reserved for large-scale hydroelectric dams. Examples are the Grand Coulee Dam in Washington State and the Akosombo Dam in Ghana.
* Micro hydro systems are hydroelectric power installations that typically produce up to 100 kW of power. They are often used in water rich areas as a Remote Area Power Supply (RAPS). There are many of these installations around the world, including several delivering around 50 kW in the Solomon Islands.
* Damless hydro systems derive kinetic energy from rivers and oceans without using a dam.
* Ocean energy describes all the technologies to harness energy from the ocean and the sea:
o Marine current power. Similar to tidal stream power, uses the kinetic energy of marine currents
o Ocean thermal energy conversion (OTEC) uses the temperature difference between the warmer surface of the ocean and the colder lower recesses. To this end, it employs a cyclic heat engine. OTEC has not been field-tested on a large scale.
O Tidal power captures energy from the tides.

Solar energy:
A solar cell or photovoltaic cell is a device that converts sunlight directly into electricity by the photovoltaic effect. Sometimes the term solar cell is reserved for devices intended specifically to capture energy from sunlight, while the term photovoltaic cell is used when the light source is unspecified. Assemblies of cells are used to make solar panels, solar modules, or photovoltaic arrays. Photovoltaics is the field of technology and research related to the application of solar cells in producing electricity for practical use. The energy generated this way is an example of solar energy.

Bio fuels:
Plants use photosynthesis to grow and produce biomass. Also known as biomatter, biomass can be used directly as fuel or to produce biofuels. Agriculturally produced biomass fuels, such as biodiesel, ethanol and bagasse (often a by-product of sugar cane cultivation) can be burned in internal combustion engines or boilers. Typically biofuel is burned to release its stored chemical energy. Research into more efficient methods of converting biofuels and other fuels into electricity utilizing fuel cells is an area of very active work.

Solid biomass:
Biogas can easily be produced from current waste streams, such as paper production, sugar production, sewage, animal waste and so forth. These various waste streams have to be slurried together and allowed to naturally ferment, producing methane gas. This can be done by converting current sewage plants into biogas plants. When a biogas plant has extracted all the methane it can, the remains are sometimes more suitable as fertilizer than the original biomass.

Geothermal energy:
Geothermal

Jenny asks…

Do you think they should include these in the new infrastructure?

Barack Obama said he wants to focus on fixing the infrastructure of America. He wants to build new roads and bridges. Good for him. Because energy is a hot button, I don’t doubt he’s going to put that on the back burner. Here is what I’m wondering. Do you think they should put helices on the roads? I’m talking about wind turbines over highways that run off the wind gusts from speeding cars. They actually have those now. I’ve seen some that are overhanging from freeways. Each of them has a helix on it. They also have vertical wind turbines inside guardrails that spin from the wind generated from cars. What do you think of that? Do you think they should encompass those into the new infrastructure?
Here is a picture of what I’m talking about.
http://www.instablogsimages.com/images/2007/10/11/two-horizontal-axis-shaped-wind-turbines-on-a-highway-signage-to-produce-wind-energy_179.jpg

Windmill Farms answers:

I have read about incorporating new technology into the transportation systems of the future and I am in favor of the idea of including wind turbines on highway overpasses. Wind turbines are a great source of alternative energy, that are cost effective and low maintenance. This new technology will generate enough power for several cities across the country.

Richard asks…

A funny Physics Problem. please help?

1. Alanzo, running at a constant 3 m/s, is the first to reach you. You stagger to your feet as he approaches, but before you can speak even the first word of your explanation, Alanzo tackles you in a perfectly inelastic collision. If you were stationary when hit and have a mass of 70 kg, what is the kinetic energy (in J) of you and Alanzo together after the collision? You may consider the collision takes place in 1-D, that you and Alanzo form an isolated system, and that Alazno’s mass is 80 kg.

2. You quickly recover from the tackle and shove Alanzo aside. By now Zacarias has arrived on the scene and you greet him warmly by completely burying the 15 cm blade of your Fällkniven F1 hunting knife in his chest. If you perform 300 J of work in the process and the blade enters normal to the surface of his chest, what is the magnitude of the average resistive force (in N) that Zacarias’s chest exerts on your knife?

3. You quickly grab the bourbon bottle from the table, spin around, and smash it across Alanzo’s face, just as he was preparing to hit you again. He staggers away, disoriented, but finally pulls himself together about 5 m from you. During this time you have retrieved your knife from the lifeless Zacarias and have thrown it with a speed of 20 m/s directly at Alanzo. The impact of the knife on his neck causes Alanzo’s to stagger backward and subsequently fall through a window and down to the alley below. During his fall, Alanzo is subject to a constant force of wind resistance of 100 N. If he hits the ground with a speed of 11 m/s, how high (in m) is the window from the ground? Alanzo’s mass is 80 kg and his initial vertical speed when he fell through the window is zero.

4. As a courtesy to the owner of the Grasshopper, you drag the lifeless, but very bloody, 80 kg body of Zacarias 10 m to the outside of the bar. The force you apply to pull the body is at a 60° angle to the floor. What is the work (in J) done by this pulling force if you drag the body at constant velocity? The coefficient of kinetic friction between the body and the floor is 0.2.

5. What is the power (in W) exerted by your pulling force if you pull the body 10 m in 50 seconds?

6. What is the power (in W) exerted by the force of kinetic friction acting on the body as you pull it for 10 m in 50 seconds?

Windmill Farms answers:

Yo. Me again. Last time the plus signs where missing for some reason and I ended up deleting my answer by mistake. Here it is again.
1. Ans = 192J
Pbefore = Pafter
m(Alanzo)v(Alanzo) = [m(Alanzo) + m(you)]v(final)
v(final) = m(Alanzo)v(Alanzo)/[m(Alanzo) + m(you)] =

KE = [1/2][m(Alanzo) + m(you)][v(final]^2

2. Ans = 2000N
W = Fs
F = W/s

3. Ans = 7.08m (I’m not sure about this one)
F(Total) = F(Weight) + F(Wind) = – m(Alanzo)g + F(Wind)
F(Total) = m(Alanzo)a(Total)
a(Total) = F(Total)/m(Alanzo) = -m(Alanzo)g/m(Alanzo) + F(Wind)/m(Alanzo) = -g + F(Wind)/m(Alanzo)

[v(Final)]^2 = 2[a(Total)]h
h = |[1/2][v(final)^2]/[a(Total)] = [1/2][v(final)^2]/[-g + F(Wind)/m(Alanzo)]|. Note that the number inbetween the || (absolute value) should be negetive.
4. Ans = 1568 J
F(Normal) = m(Zac)*g
F(Kinetic friction) = uF(Normal)
F(Total) = F(Kinetic friction) – F(Applied) = Zero N
F(Kinetic friction) = F(Applied)
W = F(Applied)s = um(Zac)gs

5. Ans = 31.36 J
P = W/t

6. Ans = 31.36 J
Check Q 4 for reason.

Please do me a favour and pick a best answer for the following. It doesn’t matter which you pick.

Http://answers.yahoo.com/question/index;_ylt=AgV0LLGeacYmTJTI4ioXOk_ty6IX;_ylv=3?qid=20101029080530AAVYOtl&show=7#profile-info-EJlD5E7Caa

http://answers.yahoo.com/question/index;_ylt=AoWPLP7MPXgKEsT3p7JSgNrty6IX;_ylv=3?qid=20101029072632AAZHQ3M&show=7#profile-info-SyQue77Qaa

http://answers.yahoo.com/question/index;_ylt=AiJ6vFh4z4JggsLn.3s7l5Hty6IX;_ylv=3?qid=20101029065808AAcZuHm&show=7#profile-info-TlDn8FBEaa

Ken asks…

Is Global Warming to Blame For Hurricane Sandy?

Windmill Farms answers:

Global warming may or may not have increased the destructiveness of it. However looking at one incident of weather and blaming it specifically on global warming is the wrong way to go about it. Warming ocean waters due to global warming more than likely did play an effect on the size and power of the hurricane but ENSO also played a large role. That is when warmer ocean waters are brought to the surface. As you can see from the link below we are currently in a neutral phase heading into the positive phase of the ENSO cycle known as El Nino.

Http://www.esrl.noaa.gov/psd/enso/mei/

The Atlantic Multidecadal Oscillation also plays somewhat of a role in modulating the ENSO cycle. Though the current understanding is that this El Nino won’t be very strong compared to prior El Ninos it most likely did play somewhat of a role. During El Nino years fewer hurricanes make landfall with the US and fewer hurricanes form due, most likely, to increased vertical wind shear.

Http://tropical.atmos.colostate.edu/Includes/Documents/Publications/klotzbach2011(us).pdf

Of course during an ENSO event different areas will be affected differently. Some areas having enhanced activity while others having decreased activity.

Http://www.atmos.albany.edu/daes/atmclasses/atm305/Kim-et-al-2011.pdf

There are a number of other events that are affecting hurricane Sandy as well including a high pressure system over Greenland and a cold air mass crossing the US.

Http://www.washingtonpost.com/local/crime/atmospheric-conditions-cause-hurricane-sandy-to-intensify/2012/10/29/4dbdf680-2209-11e2-8448-81b1ce7d6978_story.html

So while global warming may have played some role in the storm the major effects of it were oscillatory cycles and variable weather patterns. The link between global warming and hurricane activity still remains one of uncertainty though but, as global warming is affecting various parts of hurricane formation dynamics, they will be affected one way or another. It just remains to be seen as to how.

Http://www.cgd.ucar.edu/cas/jhurrell/Docs/anthes.hurricanes_globalwarming.bams06.pdf

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