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?

Conventional Energy Alternatives Nuclear, Bioenergy, & Hydroelectric Power

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

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

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…)

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

Nuclear Reactor

Inside a Nuclear Reactor Core https://youtu.be/MGj_aJz7cTs

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)

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.

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

Fukushima (2011) https://www.youtube.com/watch?v=-qtQvOxRtFk

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

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

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

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

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

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)

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

BioEnerGy Energy From Biomass

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

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

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

Ethanol, Biodiesel, And Algae Oils https://www.youtube.com/watch?v=GU0Cu45cLT4

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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