Energy Savings Analysis Flashcards
Energy saings
= energy that is not used
“negaWatt”
Measuring energy savings are difficult because
- Use and consumption can change (cold winter = more heating)
- Efficiency of power plants vary. (dependent on temperature of cooling water)
Efficiencies given for products are not always true because
those are efficiencies given under “perfect” test conditions. Use in reality will affect them differently. Think of PV panels, wind turbines and cars.
Term used to indicate efficiency of power plants
Design efficiency
Volume effect
in/decrease of energy use because in/decrease of activity.
Structure effect
in/decrease of energy use because of change in structure/activity mix.
Examples of structure effect
- From one type of available tomatoes to a variety being available
- Modal shift in transport
Savings effect
decrease of energy use by efficiency improvement. distinguish between volume vs. structure + savings.
Frozen efficiency/intensity
“Freezing” the energy used
How to get frozen activity baseline?
activity in base year X activity indicator in target year
The frozen activity baseline:
- only accounts for product growth
- difference between frozen and actual can be explained by structure and savings
Examples of activity indicators
GDP
Actual production
Energy activity
= energy per e.g. steel. (Physical indicator)
Energy intensity
= energy per GDP
Structure changes can
interfere with savings calculations. Since they are not taken into account in a frozen baseline calculation, the end result of those calculations can be unrealistic.
Indicators should be carefully chosen (example)
If you only have population and household data, you are neglecting changes in the building sector.
The example of the car, where the reference situation is 2 people, 1 old car, 50km for 10 km/ltr, becomes 2 new cards, 50 km each for 20 km/ltr
In this example there is a volume effect: double distance is driven. Energy savings effect: doubling of efficiency.
Car example with passenger km (pskm)
Reference situation is just like new situation 100 pskm, so no volume effect.
Structure effect since from 2 people in 1 car the change is 1 person in 1 car.
Reference situation
= the comparison base in energy savings calculations
Should always be for the same size/categorie, so not a large and small freezer.
Reference situation examples
- old situation
- an alternative (e.g. ICE car vs electric car)
- Average (type) use(d) (by households, etc.)
- Best available
Trias energetica
1) Reduce demand
2) Use as much renewables as possible
3) use fossils as efficient as possible
Combined vs. isolated analysis
The total savings effect from 2 or more measures can be less then when calculated separately. Example of insulation and boiler, which to install first?
In isolated analysis you can easily overestimate savings.
HDD
Heating degree days
CHP
combined heat and power production
Reasons to make/use CHP
- Saves energy (and money?) • Saves grid losses • Reduces CO2 emissions • Improves energy security • Creates autonomy - Monopoly of power producers - Unreliable grid - Back-up facility
Three aspects that help achieve maximum efficiency of CHP
- High overall efficiency
- High power-to-heat ratio
- a plant designed to meet (the base load) heat demand
4 methods of calculation power efficiencies (CHP) that correct for heat
1) Power only
2) power & heat
3) Substitution method
4) power loss factor
Power loss factor
(E out + Pout*loss factor) / Fuel input
Only in combined cycles, they have electricity loss when heat increases.
Power only
Eout / Fuel in
Power & heat
(E out + H out) / Fuel in
Substitution
Eout / (Fuel in- Reference heat)
Where reference heat = Hout / reference efficiency
The power loss factor is
a factor that for every additional unit of heat produced, loses X unit’s of electricity
pKm
passenger kilometers
The amount of kilometers one passenger travels
2 people in a car driving 50 km is 50 pKm each, therefore 100 pKm total
