1. Case Study: Sweden’s Search for Alternative Energy
“Nowhere has the public debate over nuclear power plants been more severely contested than Sweden.” “If [Sweden] phases out nuclear power, then it will be virtually impossible for the country to keep its climate- change commitments.”
Curious Questions:
Why are people hesitant to expand nuclear power programs?
If the U.S. wanted to build a new nuclear power plant in Worthington, OH would you be for or opposed?

2. Conventional Energy Alternatives
Nuclear, Bioenergy, & Hydroelectric Power

3. The most Viable Fossil Fuel Alternative?
Nuclear Power
The most Viable Fossil Fuel Alternative?

4. Getting away From Fossil Fuels
Fossil fuels are limited and pollute
We need to shift to resources that are less easily depleted and environmentally gentler

5. Conventional Alternatives to Fossil Fuels
Nuclear Power
Nonrenewable
Uranium ore is a finite resource
Hydropower
Renewable
Bioenergy
-Exert less environmental impacts than fossil fuels but more impact than the “new renewables” we will discuss in Ch. 21 (solar, wind, etc…)

6. Nuclear Power
Nuclear energy - energy that holds together protons and neutrons within the nucleus of an atom
Nuclear reactors - facilities within nuclear power plants that convert nuclear to thermal energy
Nuclear fission - the splitting apart of atomic nuclei
Drives the release of nuclear energy in power plants
Nuclei of large atoms are bombarded with neutrons, releasing energy in the form of heat, light, radiation, and more neutrons, which can split more atoms

8. Nuclear Reactor

9. Inside a Nuclear Reactor Core

10. Nuclear Power It is free of air pollution produced by fossil fuels
Public safety concerns have led to limited development
Nuclear weaponry
Radioactive waste disposal
Accidents: Chernobyl (1986) & now Fukushima (2011)

11. Chernobyl 30 years Later Steel sarcophagus (To be finished 2017)
The April 1986 disaster at the Chernobyl nuclear power plant in Ukraine was the product of a flawed Soviet reactor design coupled with serious mistakes made by the plant operators. It was a direct consequence of Cold War isolation and the resulting lack of any safety culture.

12. Three Mile Island, Pennsylvania, partial meltdown in 1979 first accident to put the world on high alert. Was a near miss, & mostly contained.

13. Fukushima (2011)

14. Where does the 235U Come from?
Uranium is used for nuclear power because it is radioactive
Uranium-235 emits radiation & decays into lead-207
The rate of decay is determined by its half-life; the time it takes for half of the atoms to decay
235U has a half-life of about 700 million years
Comes from minerals in ore which is rock that contains minerals of economic interest

15. Uranium-235
Over 99% of the Uranium in nature is Uranium-238 (3 fewer neutrons) Process the Ore to get the content to 3%
After several years in a reactor, the Uranium-235 has decayed enough that it must be replaced Used fuel is disposed of as nuclear waste

16. Nuclear Waste Management
Spent fuel rods/other radioactive waste storage remains a challenge Typically stored at the power plant itself, but many are running out of space.
Many nations are searching for a central site to store all waste, to minimize risks and keep heavily monitored/guarded

20. Project was shut down by the Obama admin
Project was shut down by the Obama admin. in 2010, after 13 billion spent on development.

21. Nuclear: More Clean than Fossil Fuels
Create energy with vastly reduced air pollution Nuclear power releases 4-150x fewer emissions than fossil fuel combustion
Fewer chronic health risks for people living near or around power plants as compared to coal Less Uranium-235 needs to be mined to generate power (unlike coal) –less landscape damage

22. Fission Vs. Fusion
Nuclear fusion- forcing together nuclei of small lightweight elements under extremely high temperature and pressure
Same energy as the sun and H-bombs Despite billions in funding and decades of research fusion in the lab still requires more energy to be put in than is returned (EROI lower than 1)

24. Modern Design
Current reactors are much safer, and designs for future plants promise more safety features. Many environmental advocates propose expanding nuclear using a new generation of reactors that are safer and less expensive Nuclear power remains one of the few currently viable alternatives to fossil fuels, in which we can generate large amounts of electricity rather quickly

25. BioEnerGy
Energy From Biomass

26. BIOENERGY
Bioenergy (biomass energy) = energy obtained from biomass resources
Biomass = organic material that makes up organisms and contains energy that originated with photosynthesis
Wood, charcoal, agricultural crops, manure
It is renewable and releases no net carbon dioxide
Carbon released by burning was pulled from the atmosphere to make the biomass

28. Bioenergy: A diverse Source
Farmer in a developing country
Bioenergy could entail cutting wood, or collecting manure by hand and burning it to heat and cook for family
Farmer in Iowa
Bioenergy might mean shipping grain to a hi- tech refinery that converts it to liquid fuel (biofuel) to run automobiles

29. Biopower Combustion Strategies
Biomass plants operate in a similar way as coal fired plants In fact, through co-firing we can sub 15% of coal with biomass (woodchips, pellets, etc.) with little modification or efficiency loss
Gasification can also be done to biomass Pyrolysis – heats biomass w/out O2 …Produces Solids/liquids/& gases that can be burned to generate electricity

30. Ethanol, Biodiesel, And Algae Oils

31. Ethanol (EtOH) The alcohol in beer, wine, & liquor
Produced by fermenting biomass
Carbs -> sugars >Ethanol
Corn
Bagasse
Sugarcane residue
Brazil-40% of their auto fuel
Normal vehicles run well w/gas blended with up to 15% EtOH.
In the U.S “big three” automakers make flexible-fuel vehicles that run on E-85
85% EtOH 15% gasoline
Most run on gas because many gas stations do not have E-85 “demand”
9 million on the road

34. So Why Not Just Switch to Ethanol fuels?
Competes with other crops, drives up food prices
Fossil fuel energy still used to produce the EtOH, machinery, refineries, etc
Soil erosion, removal of soil carbon
EROI 1.3 : 1
Bagasse significantly higher
Critics do not view corn ethanol as an effective path to sustainable energy

36. Biodiesel
Using waste oil is sustainable, however, most oil used for biodiesel comes from crops grown specifically for that purpose
Land use major impact
Similar issues as discussed with EtOH
Fuel produced from vegetable oil, used cooking grease, or animal fat that is processed with a small amount of methanol (wood alcohol) or EtOH
U.S.- soybean oil
Europe- rapeseed oil

37. New Generation BioEnergy
Algae
Grow quickly & productively can be farmed in many places (including places that crops cannot be grown)
Can produce biodiesel, ethanol, or other fuels
Cellulosic Ethanol
Generate fuel from crop waste using enzymes
Cellulose is available in all plant material
Switchgrass
Grown in the prairie, could be a habitat for animals while growing
EROI 5:1

40. Clean & Renewable, but also Has Impacts
Hydroelectric Power
Clean & Renewable, but also Has Impacts

41. Hydroelectric Power
Next to biomass, provides more renewable energy than any other source
Hydropower = uses the kinetic energy of moving water to turn turbines to generate electricity

42. Three Approaches To Hydropower
1. Storage technique = water stored in reservoirs behind dams passes through the dam and turns turbines
The amount of power generated depends on the distance the water falls and the volume released
Storage allows a predictable supply of water and electricity

44. Three Approaches To Hydropower
2. Run-of-river approach = generates electricity without disrupting the river’s flow
River water can be diverted through a pipe, passed through a turbine, and returned to the river
A small dam that does not impede fish passage can also be used to divert water
Useful where a large dam is impractical

46. Three Approaches To Hydropower
3. Pumped storage = water is pumped from a low reservoir to a high reservoir when energy demand is low; uses it when demand is high
Uses energy to pump water

47. Hydropower: Widely Used
Hydropower accounts for 16% of the world’s electricity production
Nations with large rivers and economic resources to build dams have used hydropower for their development
Sweden receives nearly 50% of its electricity and 11% of its total power from hydropower

48. Hydropower: Widely Used
However, many countries have dammed their large rivers
People want some rivers left undammed
The U.S. government built dams to employ people and help end the economic depression of the 1930s

50. Hoover dam: When operating at full power, the 17 generators can supply all the electricity needed by a city of 750,000 people.

51. Expansion is Limited
There are massive dam construction projects going on
China’s Three Gorges Dam is the world’s largest dam
Displaced 1 million people
Generates as much electricity as dozens of coal-fired or nuclear plants

52. Expansion is Limited
Most of the world’s large rivers have already been dammed, limiting potential expansion
98% of the appropriate rivers in the United States have already been dammed
People have grown aware of the ecological impact of dams and resist more construction
Developing nations with rivers will increase hydropower

53. Hydroelectric Power Impacts
Hydropower has three clear advantages over fossil fuels for producing electricity:
Positive Impacts:
It is renewable: as long as precipitation fills rivers we can use water to turn turbines
It is efficient: it is thought to have an EROI (energy returned on energy invested) of 100:1 or more
It is clean: no carbon dioxide or other pollutants are emitted into the atmosphere

54. Hydroelectric Power Impacts
Negative impacts:
Fossil fuels are used in constructing dams
Large reservoirs release the greenhouse gas methane
Damming rivers destroys wildlife habitats
Upstream areas are submerged
Downstream areas are starved of water
Natural flooding cycles are disrupted
Downstream floodplains don’t get nutrients
Downstream water is shallower and warmer
Periodic flushes of cold reservoir water can kill fish
Dams block passage of fish, fragmenting the river and reducing biodiversity

55. Conclusion Nuclear power showed promise
But high costs and public fears stalled its growth
Biomass energy sources include wood and newer biofuels
They can be carbon-neutral but are not strictly renewable
Hydropower is a renewable, pollution-free alternative
But it is nearing maximal use and can involve substantial ecological impacts