PDS AP Environmental Science 8th Period 2011-12

This article shows the future of solar energy in Africa by providing cleaner and more accessible energy to the impoverished communities.
The article mentions that the only current source of energy and heat is burning wood and coal which can cause tuberculosis and asthma. The transition utilizes solar powered hot water heaters and clean-burning cooking stoves which are types of active solar energy. This is a unique example of how solar energy can improve the health of less fortunate societies through Active Solar Energy. The other main method of solar energy is Passive Solar Heating. The major difference between the two types of solar energy is that passive solar heating doesn’t require the use of mechanical and electrical devices like active solar energy does.

Passive Solar Heating is used to collect, store, and distribute solar energy in the form of heat in the winter while also to reject solar heat in the summer. This technique takes advantage of the building design, but the designing must be done during the construction of the house or building. Examples of the building designs are things like positioning windows on the south-facing walls to let sunlight and heat in, covering roofs with dark material to maximize heat absorption, and having overhangs to block sunlight in the winter.

Here is a visual to passive solar heating:

This is a video that better explains how window positioning helps passive solar heating.

*While you don’t have to spend extra money on equipment, construction costs can run high but usually pay themselves off within a few years.

Active Solar Energy is used to convert solar energy into a more useful form of energy, such as heat or electrical energy. Examples of active solar energy are things like a small scale water heating system, photovoltaic solar cells, and large concentrating solar thermal systems. Water Heating Systems can be used for household water, public swimming pools, or businesses and is generally driven by a pump that is powered by the sun. A Photovoltaic Solar Cell is an electrical device that converts the energy of light directly into electricity. Many of the solar cells are paired together to make the solar panels that are seen on houses and buildings. Concentrating Solar Thermal Systems use mirrors or lenses to concentrate a large area of sunlight, aka solar thermal energy, onto a small area which then converts the light to heat. This drives the turbine that is responsible for generating the power.

*Active solar energy can generate hot water or electricity without polluting the air or water as it doesn’t produce CO2, but the installation of these technologies can be expensive.

Tags: energy, renewables, solar

In class on Thursday, February 9th, we had a debate on whether recycling was worth the trouble. Everyone in class was assigned to a team, either pro-recycling or anti-recycling (regardless of their actual opinion). There were 2 articles from which the teams got their information, “Recycling Is Garbage” (New York Times) is anti-recycling and “Anti-Recycling Myths” by R. Denison and J. Ruston is pro-recycling. The following are the points that were brought up by both teams:

PROS:    

• Recycling is safer for the environment; it’s more beneficial long-term to cut out the pollution from producing twice as many products.
• Without recycling, there are two options for trash disposal: landfills and incinerators. Landfills are detrimental because of the methane gas they release into the air (methane gas is more harmful than CO2, and causes global warming). Landfills use money yet don’t produce anything, and incinerators also require money, but produce minimal energy.  
• Extracting materials for new products is expensive.
• Recycling reduces the need to extract new raw materials. This way, consumers don’t pay for new materials, and recycling can pay for itself. 
• Recycling causes trash production to decrease, while having no recycling programs encourages waste production (i.e. having a waste system makes people feel better about throwing more things away and producing more waste).
• The collection, sorting, and reproduction of materials will create new jobs and opportunities for workers. Recycling can potentially pay for itself. 

CONS:

• Collecting, sorting, and the entire recycling process of the materials is more expensive than landfills.
• New technologies lessen the impact of pollution from production. This means that we don’t need the same materials that used to be necessary (for example, copper, aluminum, and glass are not required in every products as much as they used to be).
• Recycling is more expensive than landfills or incinerators, and it’s paid for by tax dollars (can be $500 million-$800 million). Some people can’t afford the additional money needed to transport the garbage away from cities to rural areas and landfills.
• Recycled materials are undesirable by most companies and businesses, so the government forces them to purchase recycled materials and therefore increase their spending and decreasing their profit.

“Recycling Is Garbage” by John Tierney

http://www.nytimes.com/1996/06/30/magazine/recycling-is-garbage.html?pagewanted=all&src=pm

“Anti-Recycling Myths” by J. Ruston and R. Denison

http://www.proprecycles.org/Commentary%20about%20Recycling.html

IMAGES:

http://www.bourboncountyks.org/recycling_program.htm

http://julesmay.wordpress.com/2007/10/02/why-recycling-is-bad-for-the-environment/

Tags: recycling, solid waste

Yesterday in class we discussed two different ways of managing forests: even-aged management and uneven-aged management. Even-aged management is basically tree farming, where the trees are cut down all at once after a certain length of time in order to get trees all the same age. It can also be called industrial forestry. Un-even aged management is also known as sustainable forestry or selective cutting. This is the method utilized in order to maintain biodiversity.

We also went over different methods of harvesting forests. There are 5 specifically that we focused on: clear-cuting, strip-cutting, selective cutting, shelterwood cutting, and seed-tree cutting.

Clear-Cutting removes all trees in an area at once, like the Onceler did in the Lorax. It gains the largest profit, but is the most detrimental biodiversity.

This is forest in California that has been clear-cut.

Strip-Cutting clear-cuts narrow strips of trees in a certain way in order to decrease erosion. This protects biodiversity by allowing the uncut areas to provide habitats and protection for animals and seeds for the cut strips to re-grow new trees.

Selective-Cutting is usually the best method to protect biodiversity. Sometimes individual trees are marked and cut, and sometimes the largest, best trees are cut. When only the best trees are harvested, however, it can harm the forest.

Shelterwood Cutting removes almost all the mature trees over a ten year period in 2 or 3 cuttings, rather than all at once. The least healthy and big trees are cut first, and the mature ones later, so there are always young trees in the forest to be able to regenerate. This is a form of selective cutting, and looks very similar.

Seed-Tree Cutting is another form of selective cutting, but this one removes nearly all trees at once. This method leaves a few seed-producing trees in deliberate places to regenerate the forest without further human intervention, or planting.

Another forest management method that we went over was prescribed burns, or controlled burns. In this method, a fire is set deliberately (under controlled conditions) to decrease fuel on the forest floor. It also enables growth for the trees that require fire to grow.

This is a surface fire under controlled conditions (a prescribed burn). The fire only burns up the fuel that has accumulated on the forest floor, so that if a forest fire broke out, it would not completely destroy the forest.

This is a crown forest fire. This occurs when there is a lot of fuel on the forest floor and it is so hot that the fire reaches the canopy of the forest.

Image sources:

http://co2insanity.com/2010/12/16/california-cap-trade-may-encourage-clear-cutting-forests/

http://finchpaper.com/2010/05/cutting-trees-sustainably-saves-forests-part-ii/

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

https://www.meted.ucar.edu/sign_in.php?go_back_to=http%253A%252F%252Fwww.meted.ucar.edu%252Ffire%252Fs591%252Ffiresci%252Froughdraw_print.htm

http://summitcountyvoice.com/2011/08/20/intensive-thinning-needed-to-restore-some-western-forests/

Tags: fire, forests, land management, land use

Today in class we started talking about population biology. Scientists can study nature at 5 different levels of complexity: individual, population, community, ecosystem, and biosphere. Today, we focused on populations.

The image below (thanks Mr. Willard) displays the levels of complexity.

A population contains all organisms and species of a particular area. It’s important to remember that when we talk about adaptations that are taking place, the populations are adapting as a whole, not the individuals. Scientists monitor populations for research, but there’s always “flux”. One equation that was highlighted today was the way to calculate changes in population size: (births + immigration) – (deaths + emigration) = change in population size. The four factors that affect population size are (obviously the four in the equation) births, deaths, immigration, and emigration.

We also discussed the 5 population characteristics. Size (N), density, distribution, sex ratio, and age structure, all of which are important in determining the traits of any population. The size is the total number of individuals with in a certain area, or how many species exist. Density is the number of individuals per unit area at a particular time. This factor helps scientists estimate if the species are rare or abundant in this area. Distribution can be expressed in three ways: random, uniform, and clumped. Random distribution has no pattern to where individuals live and grow, and uniform is evenly spaced (typical for territorial animals). Clumped distribution will be observed in animals or plants that have a higher survival rate traveling/growing in a group, whether helping to get food or just increasing protection. Sex ratio is simply the ratio of males to females, which should be 1:1, but is not always. Age structure is how many individuals fit into particular age categories, and it helps scientists guess how rapidly a population will grow. Depending on which generations have the most organisms, there might be large declines, or inclines, in population size.

We also went over growth models, where we specified the two things that every population has: a maximum potential for growth and a carrying capacity. Maximum potential for growth will only be fulfilled given ideal conditions and unlimited resources. It is known as the intrinsic growth rate (r), and the graph that it produces has a “J” shape, known as the exponential growth model. The Carrying capacity (K) is the limit of how many individuals a food supply or area can support. When growth reaches it’s carrying capacity, it slows, as shown in the logistic growth model. It has an “S” shape curve.

Exponential Growth Model                                                               Logistic Growth Model                    

Next, we touched on the two reproductive strategies. It is important to remember that whichever strategy a species utilizes, it is because they have evolved, not by choice. The two are r-selected species and K-selected species. r-selected have a high intrinsic growth rate and reproduce quickly and often (examples: mosquitoes and dandelions). K-selected have low intrinsic growth rates and do not produce many offspring very often (examples: elephants, whales, and humans).

Tags: population

I think the biggest environmental problem is probably exploitation of natural resources, since fossil fuels and stuff are nonrenewable.