Energy systems analysis

Question 1

What is merit order?

Answer 1

The order in which you choose to run existing plants, based on variable running costs. (Investment and fixed costs irrelevant).

Near the bottom during summer (electricity price low) and higher up during winter (price high)

Bottom: renewable, nuclear

Question 2

What is base-, intermediate- and peak load?

Answer 2

Baseload is the minumum electricity demand of all times, “on all the time”. High investment cost, low fuel cost. (Nuclear, coal (and CHP?)) wind and solar are coming in on baseload - but not “reliable” => increasing requirements for flexible intermediate load.

Intermediate load is the higher amount of electricity demand on top of baseload, daytime. Medium investment cost, medium fuel cost. (Natural gas) Solar is naturally on by day, but not really peak power (traditional concepts don’t fit)

Peak load is when the electricity demand is peaking, afternoon. Starts up when needed, only worth producing when price per kWh increases. Low investment cost, high fuel cost. (gas turbines fueled with oil, hydro in sweden (bc we can regulate it))

Question 3

What is capacity factor?

Answer 3

(also called load factor)

Averege annual capacity utilization of a technology

CF = P_ave / P_peak = E_ave / E_max (theoretical)

Question 4

Efficiency

Answer 4

For power or heat plants

n = E_out / E_fuel

Less than one

Question 5

COP

Answer 5

For heat pumps

COP = E_heat.out / E_electric.in

> 1! Usually 3-5

Bc it upgrades heat. Electricity => mechanical energy => upgraded heat

Question 6

Alpha-factor

Answer 6

Power- to-heat ratio

For combined heat & power plants (CHP, cogeneration)

α = E_elec.out/E_heat.out

Often 0.3-1.5

If over 1; more electricity than heat

Question 7

What is marginal electricity?

Answer 7

The electricity that adds a very small (“marginal”) amount of demand

Can be used with changes on supply side, ex. marginal technology if a nuclear reactor is shut down.

Question 8

What is average electricity?

Answer 8

A mix of all generation technologies in a system, over a certain amount of time (typically a year)

Question 9

Why is system boundaries important?

Answer 9

Appropiate boundaries can vary with queston and studied system

Question 10

What is revenue?

Answer 10

The gap bw market price and producing price (see merit order diagram).

It recovers investment costs, and afterwards is pure profit

Question 11

Rough CF for nuclear, wind and solar?

Answer 11

CF_nuclear = 1-0.9
CF_wind = 0.3
CF_solar = 0.15