Chapter 2 Flashcards
potential energy
stored energy. includes: nuclear, gravitational, chemical, and elastic energy (springs).
potential within the objects, molecules or atoms they inhabit.
kinetic energy
energy of motion
is present at particle, molecular, atomic, and subatomic levels. includes: electromagnetic, electrical, thermal, motion, and sound/wave energy
“use it or lose it” energy (will dissipate if not harnessed)
primary energy
types of energy that are available in nature.
cannot be produced and must exist within or be constantly delivered to the energy system,
sources: biomass (potential, chemical); fossil fuel (potential chemical); nuclear (potential, nuclear); hydropower (kinetic, motion); tidal (kinetic, motion); wind (kinetic, motion); geothermal (kinetic, thermal); animal (kinetic, motion)
prime movers
machines that are used to transfer primary kinetic and potential energy sources into directed and concentrated forms to produce mechanical work
(e.g. steam engines, turbines, combustion engines)
secondary energy
aka energy carriers… energy that is used but not available in primary form in the environment - includes electricity, refined fuels, hydrogen, and other synthetic fuels
first law of thermodynamics
Aka Law of Conservation of Energy
in closed systems, energy can neither be created nor destroyed.
all energy that enters a closed system must remain in that system as energy, heat, or work produced. energy input must create either desired work or be wasted (and they must sum to total energy input)
energy can be transformed from one type to another, but only the addition of primary energy sources will change the amount of energy in a system
second law of thermodynamics
Entropy increases.
in a closed system, most of the transformations of energy – the heat byproduct is lost or rendered useless (through entropy - constant diffusion from hotter to colder areas - heat becomes more diffuse, disorganized, and difficult to harness into productive use)
sankey diagram
a flow diagram showing the proportional contribution to the throughput across various stages in a system
usually for energy denominated in some unit of energy over a year
forecasts
extrapolations of current behavior. description of the system and its interrelationships (the model) and a number of variables that are used as inputs to that model.
calling something a forecast usually asserts that both the model and the input assumptions are right and that is thus approximates reality.
scenarios
different than a forecast. a modeling exercise that asks a “what if” question. modeler establishes an expectation of the relationship between different variable and the output and constructs a range of “scenarios” for the inputs.
in scenario analysis, the analyst answers the question “if A were true, what impact would that have on B”? (in forecasting, analyst presents an expectation of what A would be and as a result what B would be).
Business as usual
a scenario where each of the components of the world energy demand and supply continues along its current trajectory, the overall makeup of the energy system doesn’t change much – it just gets larger in the same proportions
Energy
the ability to do work. neither created nor destroyed once in the system, merely transformed and directed to productive uses or allowed to go unused.
total volume (or stock) of energy available to do work, at any time or within a band of time
Energy = stock, kWh, amount
Energy = Power * time
Power
the rate of what energy is physically transformed (flow). a rate of flow in the system, corresponding to a rate of energy transformed or delivered.
denominated as for example Joules/second
Power = flow. kW, rate
Energy = Power * time
useful energy
The portion of final energy which is actually available after final conversion to the consumer for the respective use.
In final conversion, electricity becomes for instance light, mechanical energy or heat
total final consumption
the end of the energy system chain – small fraction of primary energy supply
more than 70% of the energy content in the primary energy supply is lost by the time it reaches the final customer
