ENVS 350 MidTerm Exam

Name: _______________________________

Student ID:_________________________

This exam consists of 12 short/medium answer questions. Questions are either worth 10, 15 or 20 points. There are a total of 160 points available on the exam.

Write Legibly and Carefully - Sloppily prepared exams will receive a point deduction. Take your time on this exam, there is no reason to hurry through it.

In all of the questions below, please confine your answers to the space that is provided for that question. For any numerical question, be sure to show your work, don't just write down an answer.

10 Point Questions

Explain how levelized costs are determined and what some of the uncertainies are in producing a reliable estimate:
Need to discuss and define
- capital costs
- fixed costs
- variable costs
Product is then metered at relevant rate over the lifetime of the facility
Uncertainties include:
- unreliable estimates of the lifetime
- usually underestimates of the variable costs (price/distribution of fuel)
Explain how a basic electrical generator works to produce electricity.
Need to discuss
- stationary magnets
- rotating coil or loop of wire between the stationary magnets
- induces an alternating current of electricity
- faster the crank turns, the more electricity is generated
Explain why hydrogen fuel cells that use platinum as a catalyst does not represent a technology that is a scalable alternative to our transportation fuel needs:
Two main points to discuss
- Platinum abundance in the earth's crust is low relative to transportation demand (and Pt is used for other things)
- Only 1/2 the platinum in a fuel cell can be recovered/recycled and the fuel cells don't last long (only 10 years).
Describe the basic operation of a Photovolatic (PV) cell and what limites its overall operating efficiency.
- photons have sufficient energy to move electrons from the valence band to the conductor band in some material
- once in the conductor band the material is now a semi-conductor
- silicon is the material of choice
- as the material heats up collisions between the free charge and the silicon nuclei in the lattice increase and so the internal resistance of the material increases and its ability to carry a current decreases
Explain why hydroelectric power historically delivered the lowest price of electricity to the consumer compared to any other technology.
- low operational and mainteance costs
- no fuel needed
- most of the capital cost was historically borne by the government which then licenses the facility for electricity delivery (this one was left out by many responses)
Explain why wind produced electricity is projected to have the lowest levelized cost of any renewable energy technology. What aspects of this technology might conspire against achieving this low cost?
Need to discuss
- capital costs for wind are moderate
- fixed costs are very low
- variable costs are really non-existant
- MW footprint on the land is increasing: scaleable technology!
Conspire:
- future price of components (steel towers, etc) may significantly increase
- Cost of transmission lines infrastructure may defeat low levelized costs.
15 Point Questions
Qualitatively explain why the large volatility in the prince of a barrel of crude oil, over the last 12 months, makes investments in alternative energy difficult.

The price of crude oil sets the standard for the cost effectiveness of any other alternative energy technology. If this baseline fluctuates a lot, then technologies become cost effective and then non cost effective on short timescales which just leads to confusion throughout the industry and an unwillingness to invest.
Note this question did not ask about the basic behavior of the price of oil over the last 12 months.
Describe how a solar concentrator system works and what some of their limitations might be? Provide examples of currently deployed concentrator technologies.
Need to discuss

how light is concentrated (e.g. mirrors, lens)
what you put at focal point (solar sterling engine, heating oil, or even PV cells)
if heating oil (parabolic trough) it mixes with water to produce steam so that's how the electricity gets out
for solar thermal, container of molten salts stays heated, then mixes with water to make steam

Limitations:

requires large land use
low individual unit capacity
heat damage to components may limit lifetime
restricted to very sunny areas as well as direct sunlight in some cases
Deployment:

64 MW Nevada Solar One trough farm
Your best friend's eccentric Uncle insists that there are 15,000 Megawatts of wind power available on the Oregon Coast if you simply placed one "commercially available" wind turbine for every 0.5 miles of Oregon coastline. Show whether or not this claim is credible.
Essential Elements:
- Coastline is 300-400 miles long
- so that's 600-800 turbines
- "commercially available turbines" have 1.5--2.5 MW capacity. So at max that's 2.5*800 = 2000 MW; rather far from 15,000 MW (and of course the wind doesn't blow all of the time)
Explain why tranmission lines must operate at fairly high voltage and what infrastructure is used to step down those voltages.
Need to explicitly discuss the first two items
- Ohms Law: V = IR
- Power = VI I²R
- Power losses through heat dissipation (which was a buzz word phrase that many used without discussion OHMS law above) therefore scale as current squared. At constant Power if one increases V one lowers I and correspondly I² lowers considerably.
- a network of substations ratchets the high voltage down in stages
- transformers using variable numbers of coils are the agent which acts to step down the voltage
20 Point Questions
Energy History of Washington State:
Five phases
1. Coal (1870-1915) - transport to san francisco via steamers; transport to steamers via human labor, trams, etc.
2. Slow growth of hydro: 1900-1930; starts with Mossyrock dam and 8 dams are built during this period for total output of about 1000 MW
3. Federally initiated growth of hydro (1935-1975) ramp up to 25,000 MW via large dams on Columbia and Snak
4. 1970 - 1985: Failed attempt to build 5 nuclear power plants
5. 1970 - now: Renewal of coal via the Centralia Coal Power plant; large source of pollution in the PNW
Explain the qualitative parallel between the "energy dilemma" in the 1930s and our current situation as well as quantitative differences in the scale of the problem. What factors may limit our dream of having a rapidly developing green economy.
Most people got lots of points for whatever they wrote but you got more points if you included some of the following points:
- running out of fossil energy now; back then wanted a substitute for dirty coal
- we need large scale renewable energy projects; back then it was hydro
- we need improved infrastructure
- we need government initiated large scale wind and solar now that will create jobs/opportunity in a similar way that the hydro and other public works projects (e.g. roads, bridges, etc) did in the 1930s.
- But the scale is much different now: back then, when completed, hydro projects produced 45% of the nation's electricity and this was done in 10 years!
- Infrastructure takes a long time to build these days for lots of reason and wages are much higher now than then. Therefore, the equivalent of putting 150,000 people to work on various infrastructure projects in today's terms is more than we can afford with some initial stimulus package.

ENVS 350 MidTerm Exam

Need to discuss and define

capital costs
fixed costs
variable costs

Product is then metered at relevant rate over the lifetime of the facility
Uncertainties include:

unreliable estimates of the lifetime
usually underestimates of the variable costs (price/distribution of fuel)

Need to discuss

stationary magnets
rotating coil or loop of wire between the stationary magnets
induces an alternating current of electricity
faster the crank turns, the more electricity is generated

Two main points to discuss

Platinum abundance in the earth's crust is low relative to transportation demand (and Pt is used for other things)

Only 1/2 the platinum in a fuel cell can be recovered/recycled and the fuel cells don't last long (only 10 years).

low operational and mainteance costs
no fuel needed
most of the capital cost was historically borne by the government which then licenses the facility for electricity delivery (this one was left out by many responses)

Essential Elements:

Coastline is 300-400 miles long
so that's 600-800 turbines
"commercially available turbines" have 1.5--2.5 MW capacity. So at max that's 2.5*800 = 2000 MW; rather far from 15,000 MW (and of course the wind doesn't blow all of the time)

ENVS 350 MidTerm Exam

Need to discuss and define capital costs fixed costs variable costs Product is then metered at relevant rate over the lifetime of the facility Uncertainties include: unreliable estimates of the lifetime usually underestimates of the variable costs (price/distribution of fuel)

Need to discuss stationary magnets rotating coil or loop of wire between the stationary magnets induces an alternating current of electricity faster the crank turns, the more electricity is generated

Two main points to discuss Platinum abundance in the earth's crust is low relative to transportation demand (and Pt is used for other things) Only 1/2 the platinum in a fuel cell can be recovered/recycled and the fuel cells don't last long (only 10 years).

low operational and mainteance costs no fuel needed most of the capital cost was historically borne by the government which then licenses the facility for electricity delivery (this one was left out by many responses)

Essential Elements: Coastline is 300-400 miles long so that's 600-800 turbines "commercially available turbines" have 1.5--2.5 MW capacity. So at max that's 2.5*800 = 2000 MW; rather far from 15,000 MW (and of course the wind doesn't blow all of the time)

Need to discuss and define

capital costs
fixed costs
variable costs

Product is then metered at relevant rate over the lifetime of the facility
Uncertainties include:

unreliable estimates of the lifetime
usually underestimates of the variable costs (price/distribution of fuel)

Need to discuss

stationary magnets
rotating coil or loop of wire between the stationary magnets
induces an alternating current of electricity
faster the crank turns, the more electricity is generated

Two main points to discuss

Platinum abundance in the earth's crust is low relative to transportation demand (and Pt is used for other things)

Only 1/2 the platinum in a fuel cell can be recovered/recycled and the fuel cells don't last long (only 10 years).

low operational and mainteance costs
no fuel needed
most of the capital cost was historically borne by the government which then licenses the facility for electricity delivery (this one was left out by many responses)

Essential Elements:

Coastline is 300-400 miles long
so that's 600-800 turbines
"commercially available turbines" have 1.5--2.5 MW capacity. So at max that's 2.5*800 = 2000 MW; rather far from 15,000 MW (and of course the wind doesn't blow all of the time)