Energy 2 Flashcards
Why is EROEI problem for transitioning away from fossil fuels?
Fossil fuels have high EROEI
They provide a substantial amount of energy relative to the energy invested in their extraction and production
Transitioning to renewables involves technologies with lower EROEI which can impact overall efficiency of system
What are the problems with EROEI as a metric?
EROEI < 1 implies a net energy consumption
suggests that the energy input is greater than the energy output, resulting in a net energy loss which is unsustainable.
EROEI is controversial as quantification is somewhat subjective
EROEI takes no account of when the energy input is needed
Implies an “energy trap”
need high EROEI energy source to make low EROEI energy source.
What is an indicative value for EROEI for oil or gas in 1965?
By the late 1960s the EROI of coal (mostly from deep mines) began to decline while the EROI of oil remained high. The EROI for coal production in the US declined from 80:1 in the 1950s to 30:1 in the 1970s.
Coal’s EROI in the US in 1965 could have been approximately 42.
Gas’s EROI in the US in 1965 could have been approximately 75 (when you consider it has decreased from 80 in 1950 to 67 in 2005).
What is an indicative value for EROEI for oil or gas in 2005?
Oil and gas: Global EROI of 18 in 2006
Oil and gas: Global EROI of approximately 22.5 in 2005.
Gas: US EROI of 67 in 2005
*Note: EROI has declined by nearly 50% in the last decade and a half (from mid-1990s to mid 200s).
What is an indicative value for EROEI for wind power?
An indicative EROI of wind is 18.
Explain the term “greenhouse warming potential”?
Normalized measure of the amount of heat that a particular gas
will trap in the atmosphere, compared to heat trapped by
same mass of Carbon Dioxide
Because different gases are removed from atmosphere by different
processes, GWP is associated with a specified time.
What is “Carbon dioxide equivalent” (i.e. C02eq)?
Is a measure that expresses the total global warming potential of greenhouse gases in terms of the equivalent amount of CO2 over a specified time period
. In 2010, what was the approximate amount of global emissions of greenhouse gases in C02eq?
49 GtCo2eq/y
What is the current atmospheric concentration of C02 in parts per million (ppm) ?
approx 420ppm
What proportion of global GHG emissions are due to electricity generation?
25% source: epa.gov
What proportion of global GHG emissions are due to transportation?
28% source: epa.gov
According to the IPCC, what is the mean predicted sea level rise by the end of this century in a
Business-as-usual scenario (i.e. RCP 8.5) ?
According to the IPCC in the fifth report, the mean predicted sea level rise by the end of this century will be 1 extra meter.
Write down the Kaya identity and explain each term.
F = P (G/P) (E/G) (F/E)
G/P = Wealth (GDP/population)
E/G = Energy Intensity (TPED/GDP)
F/E = Carbon Intensity (Total emissions/TPED)
F is total GHG emmisions
P is total population
G is total GDP
E is total primary energy (TPE) demand
Explain what is meant by “carbon intensity”.
How many grams of carbon dioxide (CO2) emissions produced per unit of a specific metric.
Typically:
Economic output (GDP)
Energy output (kWh)
Production output (product output)
Explain what is meant by “energy intensity”
Energy intensity refers to the amount of energy used per unit of a specific metric,
Typically:
Economic output
Physical activity
Measures efficiency of energy use in relation to a particular outcome
Lower energy intensity generally indicates more efficient use of energy.
