Archive for 'Unit 12-Energy'
I don’t know why I didn’t think about this before but a while ago I found out about this seach engine, which is powered by Google, called Blackle. It saves energy by just having the background being black instead of white. It’s pretty cool, so check it out. I posted a link with specifics on how it saves energy.
Does anyone know how natural gas compares to coal and oil in amount of carbon dioxide produced per unit of energy?
I don’t really understand the “run-of-river” approach in hydroelectric power. Do engineers divert a river in order to prevent less of an environmental impact? Wouldn’t that cause MORE of an environmental impact since more of a river is affecting a greater amount of land? Or is the point of it to prevent less of an accumulation of sediment and water because more water is being diverted away from behind the dam?
1) Energy and Power Calculations
E=P x T (that’s Energy in Joules= Power in Watts multiplied by Time in time units )
Like wise P=E/T
example: How much energy (J) does a 30 W bulb use if on for 10 minutes? E=PT —> E=30W x 10 minutes x 60 seconds
2) Heat Transfer Calculations
Q=m x c x delta T
(that’s Amount of heat energy in calories or BTU= mass in grams or lbs x specific heat of water (generally 1) x change in temperature in degrees C or degrees F)
3) Cost Basis
Units Used x Price/Unit= Price
Input of Energy= output/efficiency as a decimal
Let’s say a 60W bulb is 5% efficient —> 60W=X/.05 —> 60(.05)=X —> X=3W to light
Here is a list of common efficiencies: Incandescent=5%, CFLs=20-25%, Coal Power Plant=30-35%, Nuclear Plant=25%, Car Engine=20-25%, Photosynthesis=1%
If you thought the photo by Richard Box of the “leaky” high voltage transmission lines was neat, you can check out more of his photography here. I thought that was an interesting intro to a subject your book seems to ignore-how the electricity gets from all those different types of power plants to your home:
Image source (and article on how there are plans to replace our “dumb” grid with a “smart” one): http://newsone.com/nation/associated-press/obama-administration-will-spend-3-4-billion-toward-smart-power-grid/
You need a basic working knowledge of “the grid” if you are going to make sense of some of the free response math questions on the AP exam. If you missed class, the best makeup lesson I can offer is to go through the web pages of How Power Grids Work at HowStuffWorks.com.
*Someone else has scribe duties for the energy math problems covered in class today, so look for another post soon.
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.
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.
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%.
Geothermal Energy is essentially using the earth’s natural heat for power. The way the process works is the heat from the earth warms water, which evaporates to steam. The steam is then used to turn turbines that then generate electricity. Geothermal energy is a good clean way to power and heat the world’s towns and cities without needing too much coal. There are many towns around the world reliant on geothermal energy, such as this one in China: Geothermal Town Video
The concept of using the earth to heat our homes is pretty cool, if you are more interested in figuring out how it works, check out this link from howstuffworks.com: How Geothermal Energy Works Keeping the Japan Nuclear Crisis in mind, you can’t help but wonder if other sources of energy can/would help Japan recover. To ease you curiosity, check out this news report about the potential for geothermal energy in Japan: Geothermal In Japan? In the grand scheme of things, geothermal energy provides a generally renewable source of energy. Although it cannot be used to fuel vehicles like Biomass has potential to do, it is very efficient for heating and cooling buildings. Geothermal energy is a solid investment in the world’s future.
China began planning to build the Three Gorges Dam along the Yangzi River in 1919 by Sun Yatsen. Although planning took decades, this monumental dam (the world’s largest hydroelectric dam) is finished with most construction, and hopefully it will be in maximum use within a couple of years.
In a hydroelectric dam, the flow of water is used to turn turbines to create electricity. The Three Gorges Dam is an example of a storage system because water is stored in reservoirs formed by a dam.
The Three Gorges Dam is a mile and a half wide and more than 600 feet high. The reservoir created is 400 miles long and hundreds of feet deep. For half a year, this reservoir allows 10,000 ton freighters to sail to China’s interior. The electricity produced also equals 18 nuclear power plants! This is a form of renewable energy. It is hoped that this dam will benefit both international trade and the increasing need for electricity.
Here is a general information video.
This all sounds great doesn’t it? Well there are many serious consequences of building this hydroelectric dam. The negative impacts range from environmental to social.
Some negative effects include:
- Toxic materials leach into reservoir
- Destruction of landscape
- Destruction of homes (more than 100 towns)
- 1.2 million people relocated
- Destruction of archeological sites (around 1,300 sites)
- Loss of farm land
- Silt accumulation
There are even questions about how efficiently the hydroelectric energy will be used. It is stated by government officials that as much as 1/9 of China’s electricity could come from the Three Gorges Dam-the 26 hydropower turbines will produce 18.2 million kilowatts.
To watch a video of the negative impacts, click here.
It is now up to you to decide how beneficial you think this dam will really be for China.
You can read more information from CNN.
To understand what biomass energy is, first one must know what biomass is. Biomass is defined as the total mass of living matter in a given unit of environmental area.
Biomass energy is simply the taking of that biomass or any organic material and using it as fuel by combusting it, turing it into a gas fuel, or turning it into liquid fuel.
Is biomass energy even a useful form of energy? Scotland seems to think so. Just recently Scotland has set its sights on becoming more dependent on renewable energy sources, in particular, they are interested in making it so that some of their heat energy comes from biomass energy.
This is a short video shows a good definition and summary of what biomass is and how it works. Biomass Energy.
Is biomass energy efficient? How is it considered a clean energy if it still releases carbon dioxide into the atmosphere? Is it cost effective? These are all relevant question that will be answered during our presentation. I hope this gave you a good first look at what biomass energy is and has piqued your interest maybe just a little!
We didn’t have time to discuss some “new” sources of fossil fuels, namely oil (tar) sands and oil shale. Your book briefly mentions these resources. Our neighbor to the north happens to rich in oil sands, which contains oil in a semi-solid state known as bitumen. This substance must be heated before the liquid crude oil can be extracted. This 2 minute CBS 60 Minutes video clip shows an oil sands mine and what the bitumen looks like:
As you can see in the video, this involves a lot of strip mining–a very destructive process that means much deforestation (in Canadian taiga), habitat loss, and biodiversity loss. Look at this image from a recent National Geographic article on oil sands mining:
Such destruction is one of the main reasons environmentalists oppose this method of harvesting oil. The Canadian Association of Petroleum Producers insist that such mines undergo extensive reclamation (by law), and so the environmental damage is not permanent. Here is a short YouTube video by CAPP showing the mining process through reclamation:
An economic drawback to using oil sands is the amount of energy (heat) and water that must be use in the refining process to harvest the liquid oil. Check out the steps of the refining process at HowStuffWorks.com. If crude oil prices are low, this expensive mining and refining operation may not make make a profit. But, if like the CBS video report states, Canada has enough of the stuff to rival Saudi Arabia’s crude oil reserves then we may have a way to break from of our dependence on OPEC supplies. America already imports most of its crude oil–maybe all that cash will now go to a trusted democracy?