1. Lesson 4.2: How do alternative energy technologies work?
Marisol Mercado Santiago, Ph.D.

2. Acknowledgements and disclaimer
This material is based upon work supported by the National Science Foundation Graduate Research Fellowship Program under Grant No. DGE
Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author and do not necessarily reflect the view of the National Science Foundation.

3. How this information might help you?
Because of the climate situation worldwide, many engineers are needed to design, test, and deliver technologies that make use of energy alternatives.
This presentation gives information and shows videos useful for you to see how these technologies work. It might also help you in your first-year engineering courses.

4. Alternative energy resources
Biomass
Wind
Solar
Geothermal
Tidal (rise and fall of ocean water on a shore)
Water flow (hydropower)
Nuclear
For each alternative: write their advantages or disadvantages. Bring also information from the Lessons to the power point.

5. Biomass to energy technology
Biomass could be a renewable resource if it is not harvested faster than replenished.
Biomass energy comes from bioorganic materials such as food waste, wood, agricultural waste, and animal waste that can be either burned directly as a solid fuel or converted into liquid biofuels.

6. Biomass to energy technology
Biomass can be converted to biofuels.
Ethanol and biodiesel are two examples. Ethanol is derived from fermentation of plant sugar. Starch from plant-based sources is converted to simple sugars, through a yeast fermentation. The byproduct is distilled to make ethanol.
Image source:

7. Ethanol conversion
1. The materials are grinded in the “biomass handling” phase
2. Diluted sulfuric acid is added to the biomass to generate the chemical reaction called “cellulose hydrolysis”
3. The process releases simple sugars from the material.
4. Cellulose enzymes are bought or might be produces in the same site.
5. Glucose is produces out of the chemical reactions from cellulose enzymes and the biomass.
6. Glucose is converted into ethanol through the process of fermentation.
7. A yeast or bacteria is added to the substance to produce the necessary chemical reactions. Xylose (a five-carbon sugar), is fermented with genetically engineered bacteria or zymomonas mobilis.
8. “Ethanol broth” is produced from the fermentation of glucose and the five-carbon.
9. The ethanol broth is dehydrated to remove the water. The final product and other byproducts of the biomass-to-ethanol engineered processes is used to fuel an electric generator.
Information source:

8. Advantages of biomass energy Disadvantages of biomass energy
Reduced CO2 emissions
High net energy yield from oil palm crops
Reduced hydrocarbon emissions
Potentially renewable
Large-scale farms dedicated to biomass for biofuels can decrease biodiversity in a region
Biodiesel can be more expensive than regular diesel
Can make engines hard to start in colder weather
Large-scale lands are needed to support the megawatts needed to provide energy to a town. Usually more than the land needed for solar energy
Source: Miller, G. T., & Spoolman, S. (2009). Living in the environment: Concepts, connections, and solutions. Pacific Grove, CA: Brooks/Cole.

9. Wind energy technology
Video URL:

10. Wind energy technology
NOTE: modify this slide to fit in the context of your cultural/ethnic group.

11. Wind energy technology
NOTE: modify this slide to fit in the context of your cultural/ethnic group.

12. Image source: Hodge, B. K. (2010)
Image source: Hodge, B. K. (2010). Alternative energy systems and applications. Hoboken, NJ: Wiley.
Where V = wind speed; A is the swept area of blades, and the p is the air density.

13. Advantages of wind energy Disadvantages of wind energy
High efficiency
Low electricity cost
No CO2 emissions to operate it
Can be located at the ocean
Land below turbines can be used to for farming
Visual pollution
Plastic components made of petroleum
A backup system is needed when winds are low
Can kill birds and interfere with migratory pattern of birds
Source: Miller, G. T., & Spoolman, S. (2009). Living in the environment: Concepts, connections, and solutions. Pacific Grove, CA: Brooks/Cole.

14. Solar energy technology
Solar cells are usually made of silicon (semiconductor material)
Engineers who create this technology usually work in the microelectronics industry. Trained in electrical and materials engineering.
Video:
The energy is collected from the sun’s radiance in solar cells on a building. A pumping system pumps water in the pipes. The water will be heated through the solar panel system and it will go to a heat exchanger that will emanate hot vapor into the house
New video:

15. Image source: http://ausra.com/pdfs/SolarThermal101_final.pdf
NOTE: modify this slide to fit in the context of your cultural/ethnic group.
Image source:

16. Advantages of solar energy Disadvantages of solar energy
Moderate environmental impact
No CO2 emissions relating to operating it
Fast construction
Low efficiency
High cost
Needs backup and storage system
May disturb desert areas
The energy is collected from the sun’s radiance in solar cells on a building. A pumping system pumps water in the pipes. The water will be heated through the solar panel system and it will go to a heat exchanger that will emanate hot vapor into the house
Source: Miller, G. T., & Spoolman, S. (2009). Living in the environment: Concepts, connections, and solutions. Pacific Grove, CA: Brooks/Cole.

17. Geothermal energy technology
Engineers who design geothermal energy plants need to apply knowledge of geoscience and physics in their work
Dry rocks in which heat has been accumulated up to reach temperatures of 200° C or more
Image source:

18. Geothermal energy technology
Video URL:

19. Advantages of geothermal energy Disadvantages of geothermal energy
Very high efficiency
Lower CO2 emissions than fossil fuels
Low cost at good sites (Tibet region)
Low land use and disturbance
Moderate environmental impact
Can be depleted if used too rapidly
Moderate to high local air pollution
Noise and odor
High cost, except at the most concentrated and accessible areas
Source: Miller, G. T., & Spoolman, S. (2009). Living in the environment: Concepts, connections, and solutions. Pacific Grove, CA: Brooks/Cole.

20. Tidal energy technology
Video URL:

21. Hydropower energy technology (dams)
Video URL:

22. Hydropower energy technology (dams)
Advantages of hydropower energy
Disadvantages of hydropower energy
Low-cost electricity
Reservoir useful for fishing and recreation
May provide drinking water to surrounding neighborhoods
Reduces downstream floods
Displaces people around the river
Can destroy forests
Risk of failure can be devastating
Disrupts migration of fishes and other aquatic animals
Source: Miller, G. T., & Spoolman, S. (2009). Living in the environment: Concepts, connections, and solutions. Pacific Grove, CA: Brooks/Cole.

23. Nuclear energy technology
URL of the video:
..\Videos\How nuclear energy works - YouTube.flv
Add info from the lesson!
How nuclear energy works:
Fukushima accident

24. Fukushima Accident Explained
URL of video:

25. Advantages of nuclear energy Disadvantages of nuclear energy
Large fuel supply
Emits 1/6 as much CO2 as coal
Moderate land disruption and water pollution
Needs government subsidies
High environmental impact – with major accidents
Risk of catastrophic accidents
No widely accepted solution for storage of radioactive wastes
Source: Miller, G. T., & Spoolman, S. (2009). Living in the environment: Concepts, connections, and solutions. Pacific Grove, CA: Brooks/Cole.

26. What do you know about energy alternatives in Tibet
What do you know about energy alternatives in Tibet? Which technologies could be more suitable? Which technologies could harm more Tibet’s environment?
NOTE: modify this slide to fit in the context of your cultural/ethnic group.

27. Summary How some alternative energy technologies work
Biomass to energy conversion. Ethanol conversion.
The potential of wind energy in India and Tibet
How solar energy systems work. The potential of solar energy in Tibet
How a geothermal energy technology work
How tidal and hydropower energy technologies work.
How nuclear energy technology works
Advantages and disadvantages of each technology
NOTE: modify this slide to fit in the context of your cultural/ethnic group.