Ch. W20: Conventional energy alternatives

You may notice that the Withgott 7e text divides energy into three main categories:

Chapter 19: Fossil fuels
Chapter 20: Conventional energy alternatives (nuclear, biofuels, hydropower)
Chapter 21: Emerging renewable energy (solar, wind, geothermal, ocean, hydrogen storage)

Bozeman Science:

025 - Nuclear Energy

http://www.bozemanscience.com/ap-es-025-nuclear-energy

026 - Hydroelectric Power

http://www.bozemanscience.com/ap-es-026-hydroelectric-power

This makes a great deal of sense, so below you will find notes from Chapter 20 (I may add notes from 19 later)

Chapter 20: Conventional energy alternatives (nuclear, biofuels, hydropower)

n.b. the text seems to refer to energy policies in Sweden quite a bit: why do you think?

Part I: Nuclear Power:

Fission for now:

Screen Shot 2023-01-28 at 5.18.32 PM.png

Make sure to understand the difference between U238 (common) and U235 (rare, must be refined to get, known as "enriched Uranium")

You may also hear about "enriched Uranium in the news about countries like Iran and N. Korea, where enriched Uranium can be used for nuclear weapons, as well as fuel for energy reactors

Make sure you understand each of these elements, but more, how are they similar and different from a coal fired power plant?

Screen Shot 2023-01-28 at 5.21.29 PM.png

Realize also that this is called a Pressurized light Water Reactor (PWR) which is the most common. Make sure to look up the other, more dangerous type, called the BWR or boiling water reactor. The main difference is this one has a primary loop that is separated from the secondary steam loop.

You may also hear about a PWR "heavy water" reactor, which uses depleted fuels to create Plutonium for weapons...

Good to know for the AP exam:

Screen Shot 2023-01-28 at 5.25.10 PM.png

You should also know the term "mill tailings" which are radioactive and toxic leftovers from mining and refining Uranium.

From your e2 video "coal vs. nuclear" you should be able to list a few of these:

Screen Shot 2023-01-28 at 5.26.28 PM.png

The text refers to Fusion as a "dream" but you know that recently (January 2023) Fusion achieved "break even" meaning it had an EROEI of 1:1 for the first time EVER. They've been working on this since 1950, so this is a very big deal.

Here's the reaction:

Screen Shot 2023-01-28 at 5.28.33 PM.png

Three main accidents covered in the text:

Three Mile Island: Pennsylvania, 1979

partial meltdown
still toxic
some radioactive gas released
no stats on health impact or death
caused by human error

Chernobyl: Ukraine (was USSR), 1986

human error
bad design
poor response
some killed directly
many millions impacted, early cancers (thyroid, others)
100+ tons of radioactive material released
still toxic for 20 miles around
top 2m of topsoil was removed, buried deep underground

Fukushima: Japan, 2011

tsunami, flooded electrical generators
full meltdown 3x, partial another 3x
still very radioactive, releasing radioactive water into the sea

Next big issue: nuclear waste:

dangerous to store
dangerous to move to storage sites
can be used for "dirty bombs" (conventional explosives + radioactive waste)
melts containers, can get into ground water
radioactive for thousands of years

Reactor design:

Gen 1 reactors: Submarines, early shore reactors

Gen 2 reactors: most present reactors

Gen 3 reactors: better recent design, some using heat convection like the SMR modular reactor

Gen 4 reactors: pebble bed reactor, liquid sodium reactor, molten salt reactor

Part II: Bioenergy

Basically anything that was living, used as fuel for energy

Examples:

Screen Shot 2023-01-28 at 5.39.26 PM.png

Issues:

Diversion of food
Impact on erosion, soil health, nutrients
EROEI less than 1.0 for corn ethanol in the US (very political)

Main versions:

1. Direct burning: wood, manure, bagasse

2. Fermentation: corn, sugar cane or other sugar crop grown, fermented to make ethanol (alcohol)

3. Cellulosic ethanol: using non-food crops (waste, grasses) with bacteria and yeast to create ethanol

4. Biodiesel: from oily crops (rapeseed)

5. Algal biodiesel: from algae

EROEI (energy return on energy invested)

Screen Shot 2023-01-28 at 5.45.01 PM.png

Note that EROEI for ethanol depends on where it is grown: corn (US) vs. sugarcane (Brazil)

Part III: Hydropower

Three main topics:

1. Hydroelectric dams (PE of water behind dam becomes KE of water through turbine)

2. Run of the river hydropower (KE of water flowing through turbines, no dam)

3. PSH: pumped storage hydro (essentially creating a dam or pond as hydropower storage)

Very high EROEI (80:1)
Finite lifespan for dams
Dams impact downstream life as well as upstream dislocation
Only available where there is consistent flow of water, and location for dam
Different from tidal or ocean energy, as all dams are freshwater

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