PDS APES 8th Period 2009-10

Today we talked about hydrogen and how it can be used to power vehicles. Of the forty-four free response questions on previous A.P. exams, none have addressed hydrogen power, so Mr. Willard said this would be “good knowledge to have in our pockets.”

First we reviewed what we already knew about hydrogen. Hydrogen is the most abundant element in the universe. Despite this fact, there is almost none in the troposphere, and this is because hydrogen has a very low density and so it rises. Additionally, hydrogen is very unstable, so it likes to bond with things (i.e. with oxygen, thus water).

In a hydrogen-powered car, the traditional internal combustion engine is replaced with a fuel cell. Here is a link to a video we watched in class about how a fuel cell works: How A Fuel Cell Works: Inside A Hydrogen-Powered Car (http://auto.howstuffworks.com/fuel-efficiency/alternative-fuels/dangerous-hydrogen-fuel1.htm)

As with every energy source, there are pros and cons. The pros to a hydrogen-powered car is that water is its only emission, it is a strategy for reducing fossil fuel use, and hydrogen is the most abundant element in the universe. On the flip side, the cons to a hydrogen-powered car are that we have to harvest the hydrogen or “make it” (which requires energy input), since this source of energy is new, the infrastructure for hydrogen power is not there, and that we can’t simply convert petro-gas stations to hydrogen gas stations. Perhaps we can add on to our petro-gas stations, and if we harvest the hydrogen or “make” the hydrogen by generating energy from renewable resources such as wind or solar power, technically the energy is still clean. But if we generate the energy for hydrogen from a coal-based power plant, then we’re just moving the source, but the impact is still the same.

Hydrogen can be “harvested” or “made” from electrolysis (splitting water), from biomass, and from fuel.

The U.S. Government is currently funding research on hydrogen power in the state of California. Hydrogen power is still very much in the research and development stage. Hope this helped!

Below is a picture of a typical hydrogen fuel cell:

http://images.google.com/imgres?imgurl=http://www.che.tamu.edu/groups/Wood/H2%2520movie_files/image003.gif&imgrefurl=http://www.che.tamu.edu/groups/Wood/H2%2520movie.htm&usg=__K3fNnt0v-ftXo11ZxrB83AVzpL0=&h=450&w=450&sz=26&hl=en&start=6&um=1&itbs=1&tbnid=11w-PWqxONm6CM:&tbnh=127&tbnw=127&prev=/images%3Fq%3Dhydrogen%2Bfuel%2Bcell%26um%3D1%26hl%3Den%26sa%3DN%26rlz%3D1R2GGLL_en%26tbs%3Disch:1

Last year, a student send me a 12-minute bit from 60 minutes on coal power. The piece is centered on an interview with Jim Rogers of Charlotte’s own Duke Energy. Watch this, then read on:

*IF the embedded video will not play, try this link: Powered by Coal (60 minutes)

So…what do we do in the short term? Build the “cleanest” coal-powered plants we can build AND try to capture the carbon in the ground? Regardless of our efforts, does it matter if China is not even trying while starting up one new coal-fired power plant A WEEK?!

Is our future “blowing it the wind?”

NPR posted a wonderful series last spring called Power Hungry: Reinventing the U.S. Power Grid. While some place great hopes in wind and solar, the fact remains that coal (and nuclear) provide reliable sources of power for our grid. In the segment, Constant Challenge: Constant Current from Fickle Winds, NPR exposes the main limitations of putting our hopes in wind:

At the Midwest ISO’s control room in Carmel, Ind., talk of a major increase in wind power sends chills down the spine of Rob Benbow, a grid manager. Before dawn on a spring morning, Benbow and a few dozen grid operators are shouting electricity jargon at each other in front of a massive curved screen that’s 20 feet high and 150 feet long.

As people in the Midwest wake up and turn on coffee makers and hair dryers, the operators make sure enough power is being generated to match the surge in demand. A warning signal alerts them that a power plant has unexpectedly turned off. This time, it is someone else’s problem. But Benbow worries that when wind power makes up a significant portion of his grid’s electricity, managing it will cause him frequent problems.

“My biggest fear is if you see 20 percent wind on your system, and then it comes off at a time period where you don’t have resources to replace it — that’s going to, could, result in a blackout situation,” he says.

Wind power is not predictable. That morning, the wind is steadily producing about 3,000 megawatts — about 5 percent of the total power being used in the region. But Benbow says he’s seen wind power become increasingly variable as more wind farms come on line. And grid operators can’t order wind plants to produce like they can other power plants.

“If the wind is not blowing, you just don’t have that resource available,” he says. And when the wind is blowing, it can be hard to make wind turbines shut down. “A lot of these plants are not manned — if we need to turn them off, we have to send a person out to actually do that,” he says.

Lots of other things about wind frustrate the Benbows of the world — wind blows hardest at night when electricity demand is lowest, there currently aren’t ways to store wind for later use, and you can’t count on it on hot summer days when you need it most.

“You can put all that wind in, but I still need to have all this other generation that I need to have available — all my coal, nuclear, all the gas — for my peak load day,” Benbow adds.

So, what do we do?

Alright, I am having trouble really understanding what the book means by “nuclear fuel cycle”.  All I can really find on it is the diagram and I’m having a hard time really knowing what I should be taking out of it.  Is the nuclear fuel cycle comprable to the nitrogen cycle in that it’s natural? Or is it a step by step process?  If so, what are the steps?

I know it’s late but if someone could help that would be great!

Here is today’s presentation.  While biomass is valued for being essentially carbon-neutral, you cannot ignore all the potential drawbacks to agriculture (erosion, fertilizer, pesticides, feedlots, etc…).

_______________________________________________________

Source: American Wind Energy Association

Today in class we discussed wind power– what it is, how it works, the future of windpower, and the environmental and economical trade offs of generating energy from the earth’s natural wind production as a result of unequal heating of the globe.

Wind power in the past:  Wind power has been around for ages.  It has been used to pump water from below ground and grind grain, but only recently has it been used for generating energy (mostly after 1990).  It is the ability to generate energy from wind that we are concerned about.

Source: American Wind Energy Association

Wind Turbine: wind turbines are the machinery that transfer wind energy into electric energy for use in industrial and household applications.  An example of one is pictured at the top of the post.  They consist of primarily three blades which turn the rotor, which ultimately drives the generator.  Here is a detailed diagram of the interior system of a wind turbine and how it generates energy.

• A group of interconnected wind turbines in one place is called a Wind Farm.

Advantages of Wind Power:

• Relatively clean energy– free of CO2, SOx, and NOx (low environmental impact)
• Renewable Energy
• low cost of electricity (even lower than coal, natural gas, and oil)
• Low environmental impact (small footprint, can still raise crops/livestock on wind farms)
• Can be placed off shore
• Low input and output of materials (input=wind/turbine construction, output=energy, heat, used oil, ect.

Disadvantages of wind power:

• variable source/need for backup (wind doesn’t always blow)
• Aesthetics (a valid answer on the exam)
• Noise (can be reduced by placing turbines off shore*)
• Can affect migratory birds
• impacts of harvesting materials for production

*Off shore wind turbines reduce the noise heard by nearby citizens, can be run at higher speeds where noise would be a significant problem, and can generate more consistent energy by way of daily land breezes and sea breezes.  Some producers have designed turbines that can generate upwards of 5 megawatts of power in off shore applications.  However, off shore wind turbines pose a threat to marine wildlife.

The Future of Wind Power:  Wind power currently only generates 1.6% of United States domestic energy, but it is expanding exponentially.  The United States Department of Energy projects and is striving for 20% of the United States energy consumption to be met with wind energy by 2030.  Many analysts believe it could attain upwards of 30% growth per year.  The exponential growth will provide jobs, offer another source of income for farmers and ranchers, and help the United States become less dependent on foreign sources of energy.  Here is a graph of the growth wind power has seen and will likely continue to see:

Source: GWEC Global

Side note: How big are these things?

A wind turbine blade during manufacturing.Source: American Wind Energy Association

• tower diameter: 4 meters
• rotor diameter: 70-100 meters
• blade length: 35-50 meters (land), 70 meters (offshore)
• Total weight: a mere 230- 340 tons

There are four basic math problems that we have to know for the exam.  These problems deal with basic algebra so there is NO need for a calculator.

Energy/Power:

When dealing with these problems, you must remember that energy is the ability to work and power is a rate.  For power, P=E/T and the units are in watts.  For energy, E=P x T and the units are in Joules.

Heat Transfer:

This is important for active heating. Why do we need to know this? Any time we use energy, we need to heat the water that turns our turbines and generators.  This formula seems difficult but is quite easy, Q=mc(delta)T. This quation is equal to calories or BTU( British Thermal Units).  The m stands for the mass, the c is the specific heat of water, which is equal to one, and the delta time, is the change in temperature.  When solving these problems units are a key factor and will cost you points if you forget them!

Price:

These problems deal with very simple algebra, but sometimes the problems can come across confusing.  It has a basic formula of #units x price/unit=price($).  These problems are easy to do in your head, but when you do them on paper writing down the units can help you determine your answer.  This becomes important when you are doing your energy bills at home.

Energy Efficiency:

These problems become important when you are trying to determine how efficient the light bulb you are using may be.  The efficiency can never be 100% because of the second law of thermodynamics, in the energy transfer, some energy is always lost in heat.  The formula for these problems is input=output/efficiency.  Normally efficiency is given in a percentage so you just need to convert it to a decimal to use it in the problem.

Today we took a brief look at solar power.  Solar makes up a tiny fraction (<1%) of the commercial energy market, but it is doubling every two years.  I tried to distinguish between solar electricity technologies and solar thermal (heat) technologies.

When considering solar electricity, it can be done on a small scale (homes/buildings) and a large scale (solar tower power plants).  Most folks are familiar with solar panels, or photovoltaic panels, made from two layers of silicon and divide into solar “cells.”  These panels can be bolted on existing structures or built into the roof (as shingles).  When light hits the panels, electrons are freed from silicon and flow in wiring for immediate use or storage in batteries.  Battery storage is critical, since solar incidence (amount of sunlight energy) varies by season and location and of course, since there is no sunlight at night.   Small bolt-on systems are a great solution for homes that are off an electrical grid.  A good basic explanation of PV technology is in your text, or at HowStuffWorks.com:
http://www.howstuffworks.com/solar-cell.htm

Folks are less familiar with large-scale solar-thermal power plants, like the one seen in the video below from Spain:

A huge field of mirrors follows the sun and focuses the sunlight on a central tower where water is heated to make steam, to turn a turbine, to turn a generator, to make electricity.  There are a quite a few of these in the US and other countries.

As for solar thermal technologies, they focus on capturing the sun’s heat (infrared radiation).  Unfortunately this year we will not get to tour a local home that incorporates both these techniques.  In years past, I’ve taken APES classes to the home of Jeff Martin up at Lake Norman.  From the front, Jeff’s home looks like a normal house, but if you walk around back you can see his huge solar roof:

Local Solar Home

Jeff designed the home, not just to produce electricity (the lower 3/5 of that roof) by PV cells, but also to take advantage of passive and active solar thermal technologies.

• Passive techniques: The rear of the home (and the panels) faces south to maximize the sun’s light and heat.  Also, the amount of window space is maximized on the south face of the home.  A large overhang blocks the more intense, higher sun in the summer but is designed to let the lower winter sun in completely.  The home also has concrete floors (with nice wood on top) to absorb the sun’s heat to heat the structure.  Finally, the house is super-insulated to retain all this warmth.
• Active techniques. The top 2/5 of the roof (see picture above) has copper sheets with water piped through them via a pump in the basement. The water is heated by the sun, then piped back down to the basement for storage in a huge insulated water tank.  This heated water not only provides almost unlimited hot showers, but it can also be circulated through tubing in the concrete floors to provide radiant heating for the structure.

Between all these technologies, Jeff and his family have a house that is heated and lighted in a super efficient fashion.  He further works to maximize energy efficiency with Energy Star rated appliances, super insulation, and CFL bulbs.  Of course, one of the downsides is the cost–not everyone can afford the technology on this scale.  Regardless, solar technologies are becoming more and more prevalent in the USA and enjoy even greater popularity in Japan and Germany.

What’s that you say? You want to learn about Nuclear Power? I can help you with that. Let’s get started then!

Basics

What, exactly, is nuclear power? Well, it works like coal power in a lot of ways. It involves harnessing the energy (as heat) produced in a reaction to boil water and create steam that to spin a turbine, which in turn produces electricity. Although in the case of nuclear power, we harness the energy of a nuclear reaction (fission) as opposed to a chemical reaction like burning a fossil fuel. Overall, about 6% of the world’s energy needs are met with nuclear power, with around 400 active nuclear reactors on the planet.

http://en.wikipedia.org/wiki/File:Nuclear_fission.svg

Fission

The reaction that we use in nuclear power production is called fission. Fission involves firing a neutron at a large and unstable isotope. If the neutron collides with the nucleus of this unstable isotope, the isotope breaks into two fission fragments. This breaking apart of  the isotope releases a huge amount of energy, as well as a number of free, fast-moving neutrons. These neutrons can go on to collide with other unstable isotopes, causing them to break, a chain reaction. In nuclear power production, the unstable isotope of choice is Uranium-235, one of the three naturally occurring isotopes of Uranium on earth. Before it can be used as fuel, however, it must first be mined and refined. Maybe my friend Dr. Professor Ledgewick Brambleberry XXIII and his hideous assistant Jennings can help clarify:

What we know as nuclear power uses a controlled version of this reaction to produce steam. The reaction is controlled in a light-water reactor, and involves the use of control rods and water to keep the reaction from occurring too quickly.

http://hyperphysics.phy-astr.gsu.edu/hbase/nucene/imgnuk/bwr.gif

Fusion

Theoretically, we could also use  nuclear fusionas a power source. Fusion is the reaction that occurs in the sun. In this process, two lighter elements (Hydrogen) fuse together under tremendous pressure at extremely high temperatures, forming a new nucleus of a heavier element such as Helium. We cannot, as of yet, actually create a controlled version of  this reaction. Once again, Dr. Professor Brambleberry:

Issues

One of the main concerns associated with nuclear power is radioactivity. Because the Uranium fuel used in fission is so unstable, it spontaneously decays. The products of this decay are harmful to humans, and can potentially cause burns or alter DNA. Nuclear decay can involve the release of alpha particles (two protons, two neutrons), beta particles (a free electron), and gamma rays (high-energy waves). These particle are released by the wastes of nuclear fission as well. Now to Jennings, once again.

Special thanks to Ian Noblitt for his part in the making of the videos.

Sources: Environmental Science: Problems, Concepts, and Solutions; 12th editionby G. Tyler Miller, Jr. and Scott Spoolman

Who wants to be destroyed by vicious renewable energy? Not me! So here’s what we discussed in class about the other side…NONrenewable energy.

There are four types of nonrenewable energy: Coal, Oil, Natural Gas, and Nuclear Energy. We only want to focus on the fossil fuels, which excludes Nuclear Energy.

First, lets define fossil fuels: ancient organic matter (usually plants and animals) formed by decomposition over millions of years.

A cool 85% of US energy is nonrenewable fossil fuels, and the breakdown of that is

• 23% Coal
• 39% Oil
• 23% Natural Gas

There are six categories we compared:

1. Composition
2. Top 3 Reserves
3. Primary Uses
4. Advantages
5. Disadvantages
6. Projected to Last

COAL

1. Composition: Coal is a Solid, and it is formed by anaerobic decomposition of swamps that “fold” into the earth by the shifting of tectonic plates. It is almost always found on land–you wont find any in the ocean. Every living organism is made up of Carbon, and since coal is made by the decomposition of organisms… coal is also mostly Carbon. There is also Sulfur in coal.
2. Top 3 Reserves: 1. USA (27%) 2. Russia (17%) 3. China (12%)
3. Primary Uses: Electricity and Steel
4. Advantages: Ample Supply (225-900), High Net Energy Yield, Low Cost, Developed Tech
5. Disadvantages: Land Disturbance, Air Pollution, Environmental Cost not included in market price, Gov’t Subsidies, CO2 Emissions
6. Projection: 200-900 years

OIL

1. Composition:  Liquid (aka Crude Oil). The stuff we pull out of the ground is nowhere near what you put in your cars. It is a very impure substance, mixed with hundreds of HydroCarbons. A big difference between coal and oil is HOW its formed. While coal is formed under the stress of hyper-compression from tectonic plates over land, oil is formed in the ocean. A
2. Top 3 Reserves: Saudi Arabia (25%), Canada*** (15%), Iran (10%)—- ***Most of Canada’s oil is found in an unconventional form. As in, its locked up in Oil Shales, or rocks with oil trapped in them. This makes it very difficult to extract the oil… so it takes a lot of energy to extract, and therefore there is a low Net Energy Gain.
3. Primary Use: Transportation. Minor Uses: Plastics & Asphalt
4. Advantages: Ample Supply for 42-93 years, Low Cost, High Net energy yield, low land use, Developed Tech, Efficient distribution.
5. Disadvantages Need to find substitute, large gov’t subsidies, Environmental costs,  Artificially Low Costs, Release CO2
6. Projected to Last: 42-93

NATURAL GAS

1. Composition: Gas. Mixture 50-90% methane…some Butane (like in lighters) and Propane in there as well. Note that Gasoline is NOT a natural gas.
2. Top 3 Reserves: Russia (27), Iran (15), Qatar (14)
3. Primary Uses: Heating Space, Cooking
4. Advantages: Cleanest, Ample Supplies (Although we only have 3% of the world’s reserves), low land use
5. Disadvantages:Nonrenewable Resource, Releases CO2, Gov’t Subsidies
6. Projected to last: 62-125 years