Week 2 - Chapter 2

Question 1

Kinetic Energy

Answer 1

Energy of motion - manifests at each of four levels: subatomic, atomic, molecular, particle

These correspond with five common energies:
- Electromagnetic / Radiant (Subatomic) - radiant waves i.e. ultraviolet light, visible light, microwaves, x-ray
- Electrical (Subatomic) - movement of electrons
- Thermal / Heat (Atomic/Molecular) - addition of energy to an atom or molecule increases vibration, thereby increasing temperature
- Motion (molecular/particle) - energy resident of an object in motion
- Sound or wave (molecular/particle) - energy moves as compression or vibration in air or water

Question 2

Potential Energy

Answer 2

Stored energy, resides persistently in various fuels that can be combusted. Four are:
- Nuclear energy (subatomic): Energy extant in bonds in every atom that hold subatomic particles together
- Gravitational energy (subatomic): i.e. waterfall
- Chemical energy (atomic/molecular): found in bonds between atoms and molecules, can be harnessed through forming or breaking these bonds
- Elastic energy (atomic/molecular) - in springs and polymers, hold energy in tension until they regain their natural shape

Question 3

Primary Energy Sources

Answer 3

Energy available in nature - cannot be produced and must exist within or be constantly delivered to the energy system from nature

Includes:
- Biomass (potential, chemical)
- Fossil fuel (potential, chemical)
- Nuclear (potential, nuclear)
- Hydropower (kinetic, motion)
- Tidal (kinetic, motion)
- Wind (kinetic, motion)
- Geothermal (kinetic, thermal)
- Solar (kinetic, electromagentic)
- Animal (kinetic, motion)

Question 4

Prime Movers

Answer 4

Machines that are used to harness and transfer primary kinetic and potential energy sources into directed and concentrated forms to produce mechanical work. Started out as very basic reciprocating steam engines.
- Have evolved into very sophisticated turbines and combustion devices used to perform industrial work in both stationary devices and transportation vehicles.
- These devices were intended to transform available energy - concentrate it, change its form to something easier to handle, and direct it to specific purposes
- In stationary applications, converting primary energy into electricity

Question 5

Secondary Energy

Answer 5

Forms of energy not available in a primary form in the environment, which includes electricity, refined fuels, hydrogen, and other synthetic fuels. (Sometimes referred to as energy carriers)

Question 6

Final Energy Service

Answer 6

Final products or services that are delivered by the use of energy (Toasted bread, chilled beer, spun shafts, or transported family members)

Question 7

Sankey Diagram

Answer 7

Flow diagram showing the proportional contributions to the throughputs across various stages in a system

Question 8

Business-as-usual (BAU) forecasts

Answer 8

Scenario in which each of the components of world energy demand and supply continue along their current trajectory, with the overall makeup of the energy system not changing much, just getting larger in the same proportions

Question 9

Scenarios

Answer 9

Scenario is different from forecast. Modeling exercise that asks “what if” question. The modeler establishes and expectation of the relationship among different variables and the output and then constructs a range of scenarios for the inputs. For each scenario, outputs are calculated based on the model parameters. Scenario analysis assumes that the construction of the relationships between variables is sound, but it allows that the values the inputs will take are either subject to significant uncertainty or not known.

By contrast, by calling something a forecast usually assets that both the model and the input assumptions are expected to occur, and therefore the output is expected to approximate future reality.

Question 10

Energy

Answer 10

“Ability to do work”

Units: Joules (J), Watt-hours (Wh), tons of oil equivalent (toe), barrels of oil (boe), British thermal units (Btu), or calories (cal)

E = P * t

Question 11

Power

Answer 11

The rate at which energy is transformed. Power is a rate of flow within the system, corresponding to a rate of change of energy transformed or delivered.

Units:
- joules/second transformed = watt
- Energy within a kilowatt-hour spread over an hour leaves a kilowatt (kW)
- Barrels of oil per day (bpd)

P = E/t

Question 12

First Law of Thermodynamics

Answer 12

Law of conservation of energy - all of the energy that enters a closed system must remain in that system as energy, heat, or work produced. Energy can be neither created nor destroyed.

Question 13

Second Law of Thermodynamics

Answer 13

In most transformations of one type of energy to another, some amount is wasted or rendered useless. The energy input must created the desired output (useful energy) or wasted (wasted energy). Through entropy, this heat becomes more diffuse, disorganized, and difficult to recapture.

Question 14

Useful Energy

Answer 14

Amount of energy input creating desired output or work

Question 15

Wasted Energy

Answer 15

Amount of energy input is wasted (most is in heat, though additional can be lost as light or sound or other vibration)

Question 16

Total Final Consumption / Final Energy Consumption

Answer 16

May only be a small fraction of the primary energy supply, but it has been transformed, purified, moved, directed, and distributed to exactly where the customer may find it desirable. Despite the losses, the value to the end customer has increased dramatically.

Question 17

4 Dimensions of Transformation/Fungibility Framework

Answer 17

• What: Changing the form of energy is the purpose of many transformations in the energy system. This can be any type of purification, processing, refining, or straight conversion from one energy type to another. (Low-grade to high-grade, stepping voltage up and down, removal of impurities)
• Where: Move energy from where it is to where people may find it more useful and valuable. (Firewood harvested, electricity transmitted, petroleum distributed to fueling stations)
• When: Energy is not always needed at the exact time it is available. Sources of potential energy, including biomass and fossil fuels, have an inherent ability to store their energy over time under some conditions. Any time infrastructure is deployed to assist in the temporal transfer of energy from not until later is a when transformation (underground storage, batteries for electricity, tanks for petroleum)
• How certain: Not all energy sources are available in the exact form, in the right time or place they might be desired. Buffer stocks are used to deal with uncertainties. Infrastructure designed to increase surety that energy will be available when desired.

Question 18

5 Forms of Industrial Capital

Answer 18

• Physical capital
• Financial capital
• Intellectual capital: knowledge and technology
• Political capital
• Human capital
  (plus Natural capital)

Question 19

Natural Capital

Answer 19

Many other endowments of natural capital are necessary for the complete functioning of the energy system. Examples include water availability, raw materials like metals and elements, and land.

Question 20

Stock

Answer 20

(Boxes, Energy) Rule 1. Stocks are the foundation of any system; they can be seen, felt, counted, or measured at any given time.

Question 21

Flow

Answer 21

(Arrows, Power) Rule 2. Stocks change over time through the actions of flows (mathematically, their rate of change is the first derivative of the amount of stock over time).

Rule 3. A stock can be increased by decreasing its outflow rate as well as by increasing its inflow rate.

Question 22

Feedback Loop

Answer 22

Feedback is the communication mechanism between stocks and flows, taking in data about the state of the system and communicating that data to other elements of the system, causing those elements to react by either maintaining or adjusting their behavior.

Feedback loops describe a complete cycle of these types of feedback, stocks, and flows that continually update each other. Whether they contain just a few elements or are long and complex loops of interactions, feedback loops have general properties or behaviors that can help to explain system dynamics, including:

Rule 4. Feedback loops can be sustaining or they can be reinforcing.
Rule 5. Feedback loops only affect future behavior and not current behavior; that is, lags and delays happen.

Question 23

Sustaining/Goal-seeking Loop

Answer 23

The first, a sustaining loop or goal-seeking loop, exhibits properties of stability or equilibrium. When a system that has a sustaining loop detects that stocks are too low, it causes increased inflows (or decreased outflows) and the stocks to rise. If a system detects that stocks are too high, it causes the opposite to occur.

(Home thermostat)

Question 24

Runaway/Reinforcing Loop

Answer 24

Conversely, runaway loops or reinforcing loops cause a system that is out of balance to go further in that direction. Simple examples might include avalanches, where a small amount of ice and snow dislodges larger amounts, and these larger amounts in turn dislodge even larger amounts further down. Earning interest on a pool of capital causes that pool of capital to grow, increasing the amount of interest that can be earned on it, which causes it to rise more quickly, or compound.

Question 25

System Purpose

Answer 25

Systems, when viewed dispassionately, follow a set of rules and behaviors that supersede the motivations of any one of the actors in the system. Systems are not designed; they emerge from a set of stocks, opportunities to transform those stocks, and behavioral elements that determine how the stocks and flows will change based on the conditions in the system. In aggregate, this system has an outcome, also thought of as the system purpose.

Question 26

Buffer

Answer 26

One final note about systems is that all have buffers built into them, which can represent the capacity of the system to store stocks or change flows quickly to meet opportunities and challenges presented by outside events, including shocks to the system. Similarly constructed systems with different levels of buffers may exhibit different behaviors in response to shocks. For example, systems with lots of buffers may perform better in times of volatility and uncertainty. However, building and maintaining buffers is not free, and systems in periods of relative stability would perform better by not having to maintain these stocks.

The energy system has many places where this concept of buffers applies. The various forms of potential energy, such as fossil fuels and their storage facilities, represent buffers that can be deployed to absorb excess supply or demand in the supply chain as necessary. Kinetic energy, such as wind or solar power, has no inherent buffers without supplemental storage technology. Electricity production and distribution in general has few natural buffers, but proper grid operation requires keeping sufficient excess generation capacity available to meet unexpected changes in system conditions, thereby adding buffers to this kinetic supply chain.