Module 2 Exam Questions

Question 1

What are the 5 main forms of energy?

Answer 1

a. Thermal
b. Mechanical
c. Electrical
d. Chemical
e. Nuclear

Question 2

Define the conservation of mass

Answer 2

Mass cannot be created or destroyed – coal becomes CO2

Question 3

What are the 1st and 2nd laws of thermodynamics

Answer 3

a. Energy cannot be created or destroyed
b. as energy is converted from one to another, the amount of usable energy decreases

Question 4

Distinguish between high quality and low-quality energy

Answer 4

The ability to produce work (electricity)
High quality - concentrate energy can create high temperatures (2000 degree Fahrenheit)
Low quality - hard to use to produce high temps - orange juice.

Question 5

How do fossil fuels create electricity

Answer 5

Chemical – thermal/mechanical-mechanical- electrical

We burn the fossil fuels(chemical energy) which heats water (thermal energy) which pushes a turbine (mechanical) which pushes metal through magnets to generate electricity (electrical)

Question 6

How does Natural gas create energy?

Answer 6

Natural gas replaces water in the process, does not need to be heated – now water involved in that process. Gas- turbine- generator

Question 7

What are the main sources of energy in the world? About what percentage is fossil fuels vs. clean (nuclear included) energy?

Answer 7

a. 70 -80 % fossil fuels
b. 20-30 % renewable

Question 8

How much of the US energy comes from renewable sources?

Answer 8

20-30 % renewable

Question 9

History of fuels in the US, how have the fuels to power homes, industry, and transportation
changed from the beginning of US independence to the present?

Answer 9

Biomass( wood)-coal ( steam) – natural gas- shifting to renewables

Question 10

Primary vs. Secondary energy source?

Answer 10

a. Untapped-primary – coal, solar,
b. Used by humans - electricity

Question 11

How efficient is fossil fuel generation?

Answer 11

a. Most energy that comes through fossil fuels is lost as heat (chemical – heat) ABOUT 30% EFFICIENT) 2nd law of thermodynamics
b. Renewables are more efficient, we don’t lose all the energy to heat

Question 12

Four major categories of primary energy use and what energy source is used for each?

Answer 12

a. Residential/commercial – natural gas (electricity)
b. Transportation – oil/petroleum
c. Electricity – natural gas, formerly coal but we now have fracking
d. Industrial – natural gas

Question 13

Nuclear energy: how does it work?

Answer 13

mass is converted to energy.

Question 14

Primary guiding equation of nuclear energy, how does it compare to conservation of mass and
energy?

Answer 14

E = mc^2 conservation of mass – small amount of mass is made into energy. Mass converted to energy

Question 15

fuel rods/control rods –

Answer 15

a. Control rods absorb neutrons: made of neutron absorbing material - boron and graphite
b. Fuel rods – uranium pellets

Question 16

Difference between fission and fusion?

Answer 16

a. Fission-break apart – currently used
b. Fusion – join together – not cost effective – better because no waste – Sun does fusion – needs to much upfront energy.

Question 17

uranium-235 vs. U-238: which one do we use for nuclear and how do we get it to a useable
amount for energy purposes?

Answer 17

We need to enrich Uranium 238 – separates 235 from 238 using centrifuge. 235 lighter rises to top so we skim it off. Increases concentration by separating the 2. 235 less stable more likely to split.

Question 18

Advantages and disadvantages of nuclear energy, need to be able to list and explain at least 3 each

Answer 18

Advantages :
i. High yield/efficient
ii. No carbon emissions
iii. Longer lasting Plants?Disadvantages:
i. Radiation
ii. Wasted
iii. Non renewable

Question 19

new designs/improvements for nuclear power plants?

Answer 19

a. better cooling systems – passive(shut down without human action) versus active. Light water reactors, pebble bed modular reactors(see last page)
b. Gravity powered control rods
c. Internal Cooling System
d. Most in Asia – gen 3

Question 20

Challenges of Hydrogen Economy

Answer 20

No infrastructure in place, challenging to make, split water with energy

Question 21

what do we currently do with spent nuclear fuel rods?

Answer 21

We currently hold them in Nuclear power plants, first in water and then out side. We plan to bury them, but it is challenging to locate a stable environment. Yucca Mountain is one of the options.

Question 22

What happened at 3 mile island?

Answer 22

Open valve drained water from reactor vessel, operators shut down emergency cooling system, and gauges incorrectly reported that reactor had water. Released 10 million curies of radioactive gas. No deaths reported but the plant will not reopen

Question 23

What happened at Chernobyl?

Answer 23

Engineers shut off safety systems, withdrew control rods, shut off steam to generators, and decreased the coolant water. Radioactive energy built up and exploded. At least 30 people died because of it. Building is abandoned with 1000 mile zone

Question 24

What happened at Fukushima Daiichi?

Answer 24

Earthquake and tsunami hit. Power loss from the grid and backup generators meant no cooling water. Boom!

Question 25

new designs/improvements for nuclear?

Answer 25

• Passive safety systems
• operate with no human intervention or electrical power
• gravity powered control rods
  -internal cooling system
• Most new reactors in asia are gen 3
  -Pebble bed modular reactor
  -Fusion reactors

Question 26

the potential for conservation as a means of addressing limited energy resources?

Answer 26

Insolation - Orientation (40 - 60%)
Insulation - R 40/80, windows
Installation - Infiltration
Led Lights
Low Flow showers
water conserving appliances

Question 27

passive solar in detail- How should we design houses to take advantage of solar energy?

Answer 27

We can design houses to take advantage of solar energy by orienting them south with large windows to let the sunlight in. Better insulation will hold that heat allowing us to save energy. It can save 40-60 % in yearly energy costs. Awnings can provide balance in the summer. High heat capacity materials will trap hat inside and low reflectivity materials will convert light to heat inside.

Question 28

direct solar – list and explain each of those listed in class in a fair bit of detail including their
basic operation and what they produce.

Answer 28

a. Photovoltaic Cells (PV) – made of silicone, only 25 % efficient.
b. Concentrated Solar Power (CSP) – natural heat from the sun, use a large mirror. Focus all heat to one area, transfer that heat to a turbine which turns generator which creates electricity – heated fuel (oil, molten salt). Can be store. Different types in dishes, linear mirrors, power towers, troughs

Question 29

indirect solar - list and explain each listed in class in a fair bit of detail including their basic
operation and what they produce.

Answer 29

a. Hydropower – the weather cycle – heat from the sun evaporates water, goes up into the clouds, condenses, falls as rain to a higher point of elevation, gets pulled downhill by gravity – we use it.
b. Wind power – Sun heats air, air moves creating wind, wind pushes turbine
c. Biomass energy – Photosynthesis - biomass generator anaerobic reactor

Question 30

Know the advantages and disadvantages of renewable energy sources

Answer 30

a. Advantages:
i. Renewable
ii. Clean
iii. Cheaper in the long run
b. Disadvantages:
i. Expensive up front
ii. Challenging to store energy
iii. inconsistent

Question 31

geothermal energy – both as a heat pump and at utility scale

Answer 31

heat from earth’s crust warms water that seeps to underground reserviors. As hot water comes to the surface it become steam and runs a turbine. Below ground also remains a consistent temp so we can use it to moderate our water’s heat.

Question 32

storage of renewable- list and describe types of storage

Answer 32

By pumping water back up through a hydro mill. Fuel Cells (hydrogen-oxygen), and heating oil with CSP

Question 33

How does Nuclear energy work?

Answer 33

The objective of nuclear power : to control a nuclear reaction, so energy is gradually released as heat. This heat is used to boil water to produce steam which then turns a conventional turbine- generator. main difference between 2 types is fuel source. Stuff changes at the atomic level unlike other things