Check out this video on life cycle
http://www.storyofstuff.com/
Energy Analysis
Various metrics Efficiency (η) Energy return on investment (EROI) Energy payback time (EPT) Fossil fuel ratio (FFR) Petroleum input ratio (PIR) Net energy value (NEV)
Energy Balance
Eo = energy output (e.g., useful energy) Ed = direct energy input (e.g., fuel) Ei = indirect energy input
Eic = indirect energy – continuous (e.g., energy to produce fuel) Eiot = indirect energy – one-time (e.g., energy to make device)
ts = system life (used to convert Eiot to annual energy Eiot/ts)
Energy Analysis Metrics
Eo = energy output (e.g., useful energy) Ed = direct energy input (e.g., fuel) Ei = indirect energy input
Eic = indirect energy – continuous (e.g., energy to produce fuel) Eiot = indirect energy – one-time (e.g., energy to make device)
ts = system life (used to convert Eiot to annual energy Eiot/ts)
10 EE efficiency conversionDirect
d
o
1*0 EE
Eo* efficiencyenergy Overallid
Energy Analysis Metrics: Efficiency
Eo = energy output (e.g., useful energy) Ed = direct energy input (e.g., fuel) Ei = indirect energy input
Eic = indirect energy – continuous (e.g., energy to produce fuel) Eiot = indirect energy – one-time (e.g., energy to make device)
ts = system life (used to convert Eiot to annual energy Eiot/ts)
Metrics: Net Energy
i
o
EE EROI investmentenergy on returnEnergy
o
iot
EE EPBT mepayback tiEnergy
io EEvalueenergyNet Eo = energy output (e.g., useful energy) Ed = direct energy input (e.g., fuel) Ei = indirect energy input
Eic = indirect energy – continuous (e.g., energy to produce fuel) Eiot = indirect energy – one-time (e.g., energy to make device)
ts = system life (used to convert Eiot to annual energy Eiot/ts)
Metrics: Focus on Carbon, Petroleum
FFid
o
)E(EE FFR ratio fuel Fossil
o
Petroid
E)E(E PIR ratioinput Petroleum
Eo = energy output (e.g., useful energy) Ed = direct energy input (e.g., fuel) Ei = indirect energy input
Eic = indirect energy – continuous (e.g., energy to produce fuel) Eiot = indirect energy – one-time (e.g., energy to make device)
ts = system life (used to convert Eiot to annual energy Eiot/ts)
Getting Energy Use Data
Billing meters (e.g., gasoline pumps, electric, natural gas meters)
Monitor run-time: energy used = run-time (hrs) x energy/time
Submeters, data loggers
Time-value doesn’t matter much for short time periods and low discount rates
Present value of $100 Future dollars:a. d=4%, n=10 years
b. d=1%, n=10 years
c. d=10%, n=0.5 years
d. d=10%, n=10 years
Simple Payback Period (SPP)
Time to payback initial cost with energy savings
IC = initial cost (or cost difference when comparing options), $
AES = annual energy savings, energy units/year Pr = energy price, $/energy unit
(years) x Pr AES
IC SPP periodpayback Simple
Cost of Conserved Energy (CCE)
Cost per unit energy saved that can be compared to existing rates
1-d)-(1d)d(1 (CRF)Factor Recovery Capital n
n
CRF takes one-time payment and spreads it out over the lifetime (n) of the measure based on a discount rate (d)
Other Economic Factors
n)d1(1 (PVF) Factor ValuePresent
n
n
d)d(11-d)-(1 (UPVF) Factor Value Present Uniform