Electricity can be generated from many renewable energy sources. In this lesson, we'll take a closer look at hydroelectric, biomass/solid waste, geothermal, solar and wind energy sources.
With the successful completion of this lesson, you will be able to:
The table below provides an overview of the requirements for Lesson 7. For details regarding the assignment, refer to the page(s) noted in the table.
Please refer to the Calendar in Canvas for specific time frames and due dates.
REQUIREMENT | LOCATION | SUBMITTED FOR GRADING? |
---|---|---|
Reading: (Hydropower):
|
Page 2 |
No |
Reading: (Biomass/Solid Waste):
|
Page 3 | No |
Reading: (Geothermal):
Viewing
|
Page 4 | No |
Reading (Solar):
|
Page 5 | No |
Reading (Wind):
|
Page 6 | No |
Interactive Tool: National Geographic "Harness the Power of the Wind" video and simulation | Page 6 | No |
Lesson 7 Activity: Complete Lesson 7 Activity. (It's in Canvas, in the Unit 3 Module) | Page 7 | Yes |
Unit 3 Discussion Forum: "Smart Grid" (It's in Canvas, in the Unit 3 Module) | Page 8 | Yes |
If you have any questions, please post them to our Questions about EGEE 401? Discussion in Canvas. Use this Discussion for general questions about course content and administration. I will check it daily to respond. While you are there, feel free to post your own responses if you, too, are able to help out a classmate or have a related question.
Before beginning our closer look at individual renewable energy sources used for electricity generation, let's frame the discussion with current data about actual electricity generation from these sources. How much electricity do you think we currently generate from renewable energy sources such as wind? solar? biomass? (Hopefully you remember from last lesson!) Based on ads we see on television, you'd think it is a lot, right? Here are some numbers, from the U.S. Energy Information Administration [1]. (Chart generated by course instructor using most recent full-year data.)
Energy Source | Percentage |
---|---|
Coal | 30.4% |
Nuclear | 19.7% |
Natural Gas | 33.8% |
Hydro | 6.5% |
Wind | 5.6% |
Biomass | 1.5% |
Geothermal | 0.4% |
Solar | 0.9% |
Other | 1.0% |
Hydropower, or hydroelectricity, uses the motion of water to turn a turbine and generate electricity. The water may be in a moving river (run-of-the-river hydro), moving from higher to lower elevations through a specially constructed dam, or in the motion of ocean tides or waves. Hydropower is the most widely used renewable energy source for generating electricity.
The U.S. Geological Survey's (USGS) Water Science for Schools [2] describes a typical hydroelectric plant:
[Referring to picture, Hydroelectric Dam]
The theory is to build a dam on a large river that has a large drop in elevation (there are not many hydroelectric plants in Kansas or Florida). The dam stores lots of water behind it in the reservoir. Near the bottom of the dam wall there is the water intake. Gravity causes it to fall through the penstock inside the dam. At the end of the penstock there is a turbine propeller, which is turned by the moving water. The shaft from the turbine goes up into the generator, which produces the power. Power lines are connected to the generator that carry electricity to your home and mine. The water continues past the propeller through the tailrace into the river past the dam. By the way, it is not a good idea to be playing in the water right below a dam when water is released!
Visit Department of Energy, Energy Explained [4].
Even though it is an established technology, hydropower is still very much in the news. During a White House forum in Pennsylvania that I attended in 2009, the then U.S. Energy Secretary Steven Chu said, "Hydropower capacity in the United States could double with minimal impact to the environment," clearly dismissing the notion that U.S. hydropower production has peaked. Chu said the industry could add 70,000 MW of capacity by installing more efficient turbines at existing hydroelectric projects or at dams without power components, increasing the use of pumped-storage projects, and encouraging the use of run-of-the-river turbines. "We will be pushing this," Chu said. "We're not talking about a lot of large, new reservoirs. Just work with what we have and it's a massive amount of power." (source Hydroworld [5]):
Shortly thereafter, funding for new hydroelectric projects was announced. Between 2009 and 2011, consumption of electricity generated by hydropower in the USA grew from 2,539 to 3,171 trillion BTUs. (EIA, Total Energy [6])
Read 3-Year DOE Study Assessed Potential Hydropower Upgrades in the US [7].
Biomass is carbon-based biological material, such as wood, crops (such as corn or sugar cane), leftovers from agricultural processes (such as corn husks, manure), certain by-products of food processing, and much industrial and post-consumer waste.
Biomass essentially stores energy from the sun (through the process of photosynthesis). This energy can be released in a number of ways, including burning, decay (rotting), or through processing to create biofuels (such as ethanol from corn) and biodiesel (from waste oil or vegetable oil). The following introduction from the Biomass Energy Centre [9] is a good starting point for understanding biomass/solid waste and its role in energy production.
Biomass is biological material derived from living, or recently living organisms. In the context of biomass for energy, this is often used to mean plant based material, but biomass can equally apply to both animal and vegetable derived material.
Plant material
The carbon used to construct biomass is absorbed from the atmosphere as carbon dioxide (CO2) by plant life, using energy from the sun.
Plants may subsequently be eaten by animals and thus converted into animal biomass. However, the primary absorption is performed by plants.
If plant material is not eaten, it is generally either broken down by microorganisms or burned:
These processes have happened for as long as there have been plants on Earth and is part of what is known as the carbon cycle.
Fossil fuels
Fossil fuels such as coal, oil, and gas are also derived from biological material; however, from material that absorbed CO2 from the atmosphere many millions of years ago.
As fuels, they offer high energy density, but making use of that energy involves burning the fuel, with the oxidation of the carbon to carbon dioxide and the hydrogen to water (vapour). Unless they are captured and stored, these combustion products are usually released to the atmosphere, returning carbon sequestered millions of years ago, and thus contributing to increased atmospheric concentrations.
The difference between biomass and fossil fuels
The vital difference between biomass and fossil fuels is one of time scale.
Biomass takes carbon out of the atmosphere while it is growing, and returns it as it is burned. If it is managed on a sustainable basis, biomass is harvested as part of a constantly replenished crop. This is either during woodland or arboricultural management or coppicing or as part of a continuous programme of replanting, with the new growth taking up CO2 from the atmosphere at the same time as it is released by combustion of the previous harvest.
This maintains a closed carbon cycle with no net increase in atmospheric CO2 levels.
Visit Department of Energy, Energy Explained [4].
Visit the EPA,
Visit Department of Energy, Energy Explained [4]..
Under “Renewable Sources," read "Geothermal" and all subpages.
Visit Department of Energy, Energy Explained [4].
The opening page of this section lists two main benefits of solar energy (does not produce air pollutants or carbon dioxide and when located on buidlings, minimal impact on environment). This list omits other "main" benefits of solar energy, including: the fuel is widely available, renewable and free. There is no basis for fighting or wars over solar. One country cannot take another's solar energy resources. (Same is true for wind resources.) Also, notice the EIA's "two main limitations" of solar. Did you see similar language in any other sections related to other energy sources in Energy Explained? Do other energy sources not also have "main limitations"? Consider this.
The major components of photovoltaic solar electric systems are solar modules and inverters. Solar modules typically have a 20 or 25-yr warranty. Solar electric systems, installed properly, can be expected to last and continue to produce electricity for at least 25 years. Fixed-mounted systems (arrays that don’t move) generally require very little maintenance. Solar modules generate direct current (DC) that must be converted to alternating current (AC) for standard household use. This is done by an inverter. This piece of equipment has an expected life of 10-15 years and will probably need to be replaced during the life of the system.
The phrase “solar energy” is used broadly in reference to many different solar energy technologies and processes. The photovoltaic effect , for example, converts energy from the sun directly into electricity. Another form of "solar energy" concentrates the heat of the sun to produce steam to generate electricity (similar to the way other fuels are used for generation). The heat from the sun can also be used to heat water for use in your home (doesn’t involve electricity). Plus, the heat from the sun can be used to warm surfaces in a well-designed building (passive solar), providing comfort after the sun sets. All of these applications are “solar energy.” Some involve electricity, some do not.
Visit Department of Energy, Energy Explained [4]. Under “Renewable Sources," read "Wind" and all subpages.
Visit the Department of Energy Wind Program and watch the animation "How Does a Wind Turbine Work? [18]" Click through to Text Version for "The Inside of a Wind Turbine" [19], where you will find fully labeled systems and additional info.
Visit The National Renewable Energy Laboratory [20].
Visit the European Wind Energy Association (EWEA) [21]
Complete the Lesson 2 Activity. (It's in CANVAS, under Modules, Unit 3.)
Unless noted otherwise, correct answers come directly from the content of this lesson and assigned readings.
The Activity consists of a variety questions of different types, which may include true/false, multiple choice, multiple select, fill in the blank, ordering, and short answer. The point value varies and is indicated for each. Some questions are graded automatically, and some are manually graded.
The quiz is not timed, but does close at 11:59 pm Eastern Standard Time on the due date as shown in CANVAS.
Questions that are "manually graded" will be scored based on the correctness and quality of your answers. Thinking is good! Try to make your answers as orderly and clear as possible. Short is good, as long as you fully answer the question. Help me understand what you are thinking, and include data where relevant.
Numbers must ALWAYS be accompanied by units of measure (not "300" but "300 kW").
Proofread and spell check your work.
A report from the White House presents estimates of weather-related power outages costing the US economy $25 to $70 billion a year (inflation adjusted). These costs include lost output and wages, spoiled inventory, delayed production, inconvenience, and damage to the grid itself. Severe weather is the "number one" cause of power outages in the United States and the number of outages caused by severe weather is "expected to rise as climate change increases the frequency and intensity of hurricanes, blizzards, floods and other extreme weather events." (Economic Benefits of Increasing Electric Grid Resilience to Weather Outages [22], Executive Office of the President, August 2013.)
Power failures are expensive, disruptive and can be dangerous. After no significant power losses for a decade, our home has been without power for weeks over the last several years, a result of changing weather and aging infrastructure –freak ice storms, Sandy, local equipment failure. All events were costly in terms of work productivity, loss of property and expensive emergency measures to find safe and warm temporary housing. Compounding the misery, like many, we received poor or no information about the status of our service, and the info we did receive was often very wrong. We received numerous calls from the utility and even a visit from a worker to tell us our service was restored when the street was still lined with downed poles. (Can you imagine THAT conversation?) I'm sure many of you have your stories too!
One possible remedy to help prevent and then manage before, during and after grid failures is the smart grid. Recent events, like severe winter weather and Hurricane Sandy, have drawn attention again to the Smart Grid. The promise of its benefits are beyond mitigation of power outages, however, it may also help us use energy more efficiently through information and personal behavior as well as automation and intelligent controls. The Smart Grid could also help integrate distributed generation smoothly into the grid, especially important for intermittent renewable energy sources such as solar and wind. ("Distributed generation" simply means the electricity is generated at or near its point of use.)
In this discussion, we'll talk about what the smart grid is, its promises and challenges and what it may mean to you.
Use material from the lesson and your own independent research. In your posting, please address the following;
Respond. Read the postings of others and respond to at least one.
Please define and explain any acronyms or abbreviations you use (GHG = greenhouse gas) and wherever possible include links to your references. Any questions, just let me know!
Post your work in the Discussion, "Smart Grid" You'll find it in CANVAS, in the Unit 3 Module. Please follow full instructions there.
Read the postings of others and respond to at least one. Follow up on any postings made to your comment.
Please see Canvas calendar for due date of your FIRST posting and date when discussion ends (graded participation ends, all replies must be in).
You will be graded on the quality of your participation. Be interesting and interested! Please see Syllabus for full Discussion Forum grading criteria.
In this lesson, you learned about renewable energy sources for the generation of electricity. This lesson covered hydropower, biomass, geothermal, solar, and wind sources for electricity generation, including how the generation process works and environmental considerations.
You have finished Lesson 7. Double-check the list of requirements on the Lesson 7 Overview page to make sure you have completed all of the activities listed there before beginning the next lesson.
Links
[1] http://www.eia.gov/tools/faqs/faq.cfm?id=427&t=3
[2] http://water.usgs.gov/edu/hyhowworks.html
[3] https://www.e-education.psu.edu/egee401/sites/www.e-education.psu.edu.egee401/files/image/lesson07/Hydroelctric_LD.html
[4] http://tonto.eia.doe.gov/energyexplained/
[5] http://www.hydroworld.com/index/display/article-display/6337973254/articles/hydro-review/volume-28/issue-8/-departments/breaking-news__hydro.html
[6] http://www.eia.gov/totalenergy/data/annual/showtext.cfm?t=ptb0804a
[7] http://dailyfusion.net/2013/05/3-year-doe-study-assessed-potential-hydropower-upgrades-in-the-u-s-7296/#
[8] http://www.nytimes.com/2015/04/23/business/energy-environment/troubling-interdependency-of-water-and-power.html?ref=topics
[9] http://www.biomassenergycentre.org.uk/portal/page?_pageid=76,15049&_dad=portal&_schema=PORTAL
[10] https://www.epa.gov/smm/sustainable-materials-management-non-hazardous-materials-and-waste-management-hierarchy
[11] https://www.epa.gov/smm/energy-recovery-combustion-municipal-solid-waste-msw
[12] http://www.sciencemag.org/news/2017/01/wood-green-source-energy-scientists-are-divided
[13] http://www.power-technology.com/projects/the-geysers-geothermal-california/
[14] http://www.nrel.gov/data/pix/searchpix.php?getrec=16814&display_type=verbose&search_reverse=1
[15] https://www.youtube.com/watch?v=y_ZGBhy48YI&feature=player_embedded
[16] http://www.nrel.gov/data/pix/searchpix.php?getrec=16604&display_type=verbose&search_reverse=1
[17] http://www.nrel.gov/data/pix/searchpix.php?getrec=16710&display_type=verbose&search_reverse=1
[18] http://energy.gov/eere/wind/how-does-wind-turbine-work
[19] http://energy.gov/eere/wind/inside-wind-turbine-0
[20] http://www.nrel.gov/wind/
[21] http://www.ewea.org/wind-energy-basics/how-a-wind-turbine-works/
[22] http://energy.gov/sites/prod/files/2013/08/f2/Grid%20Resiliency%20Report_FINAL.pdf