PDS AP Environmental Science 8th Period 2010-11

Does anyone know how natural gas compares to coal and oil in amount of carbon dioxide produced per unit of energy?

Wind energy is considered a distant form of solar energy because wind is caused by the sun’s uneven heating of the earth. It is, therefore, perpetually renewable. We are able to use wind as a form of energy by utilizing wind turbines. In a very basic sense, wind turbines use the wind to generate kinetic energy and then convert that energy into electrical energy.

This is a great short video that introduces the function of a wind turbine.  ——-> Energy 101 – Wind Turbines

The idea of harvesting wind energy has been used for several centuries. For the past 800 years, European farmers have used the rotational energy of windmills to pump water and irrigate their crops.

A windmill built in 1865 near Berlin Source: Wikipedia

The modern version of these windmills are wind turbines. Wind turbines range from 40 to 100 meters in height and are most often found in wind farms (large areas with hundreds of turbines). The nacelle is the unit atop the turbine from which the blades extend. Inside the nacelle are the gearbox and the generator. Once the wind turns the blades, the rotation of the blades makes the gearbox spin. The the kinetic energy that turns the gearbox is fed into the generator, which converts the energy into electricity.

A Nacelle - © EERE Source: http://www1.eere.energy.gov/windandhydro/wind_how.html

Though wind power makes up a small percentage of the world’s total energy, it is quickly growing. Germany, Spain, and the U.S. generate the largest amounts of energy from wind each year, however, Denmark currently generates the highest percentage of their energy from wind, around 20%.

In recent news, it has been reported that Germany is in the process of abandoning the generation of energy through nuclear power and turning toward more renewable and safe forms of energy, such as wind power, because of the recent tragedy in Japan. They hope to replace all nuclear energy by the year 2020. One way in which Germany plans to accelerate the use of wind energy is to build wind farms along the coast. To read the full story about Germany’s energy transition, click here.

So I’ll probably have some more questions later, but which aquatic zone has the highest NPP per meter squared? Is it estuaries? Also, I can only find 5 of the 7 in our book. I have Open Ocean, Coral Reefs, Intertidal Zones, Salt Marshes, and Estuaries. Which ones are missing?

Our text defines urbanization as the shift from people living in rural areas to people living in urban areas and is probably the greatest change our society has undergone since the transition from a hunter-gatherer lifestyle to a settled agricultural lifestyle. What exactly is an urban area? An urban area is place with a population of 2,500 or more people. This said, around 50% of the earth’s population lives in urban areas, those urban areas only occupy about 3% of Earth’s land surface area.

Tokyo is the world's most populated metropolis with over 35 million people

Is this statistic good news or bad news for the future of our planet? It all depends on who you ask. An environmentalist would say that dense, crowded cities are very much a good thing because more forests and farmlands are being preserved. However, some environmentalists would deem this a bad situation because these urban areas, especially the highly populated cities, require many inputs and therefore produce just as much waste. This waste is taken out of the urban areas and will most likely be buried in the farmlands.

An urban area, and especially a city, is a system. All systems receive inputs, process these inputs, and produce outputs. CITIES AND URBAN AREAS ARE NOT SELF-SUSTAINING; they rely on importing almost all their necessities to function. Here are the inputs and outputs of a city system:

INPUTS:                                      OUTPUTS:

People                                           Money/Jobs

Goods                                            Solid Waste

Food                                              Pollution (water, air, light, noise)

Water                                            Heat

Energy (gas, electricity)

The production of money and jobs in urban areas provokes wealth, education, technology, and health. The massive amount of heat produced by cities gave rise to cities being nicknamed “heat islands.” This is because the dark asphalt of the paved roads absorbs the heat from the sunlight and then slowly releases it back into the city air.

Air pollution over Santiago, Chile

A Quick Introduction to Urban Sprawl:

Sprawl is the spread of low-density urban or suburban development outward from an urban center. Urban sprawl is more likely to occur in the “developing” countries of the world because the Average Growth Rate of these countries is much higher than in “developed” countries, so, the populations of urban areas in “developing” countries are growing much more rapidly, creating a need to increase the size of the urban area. Regarding the statistic I began my post with, research shows that by 2030, 60% of the world population will live in urban areas.

To see examples of urban sprawl in different countries around the world from the 1970s to 2000, click the UN Urbanization Preso Slides in the Box. These are the pictures we looked at today in class.

Sources:

http://en.wikipedia.org/wiki/File:Skyscrapers_of_Shinjuku_2009_January.jpg

http://en.wikipedia.org/wiki/File:Santiago30std.jpg

Hey guys!

Could someone explain why the profundal part of a river is the most oxygenated? I would have thought it would be the top where plants are able to do photosynthesis, but that wasn’t the right answer on our test.

Thanks!

I’m looking through my notes, and I can’t really tell the difference between an aquifer, the water table, and groundwater. It seems like they’re all really similar to me. What’s the difference??

I think that the most pressing issue of Environmental Science is that fact that we are depleting all of our natural resources much faster than they replenish themselves.