# Homework Help: Calculating energy capacity !

1. Sep 14, 2011

### thedunce22

Wasn't sure if this was the right location for this, but seemed more electrical engineering based. Just doing tutorial exercises WHICH I CANNOT EVEN FIGURE OUT WHERE TO START.

-Town Population - 100 000, average 4 people per household
-Average consumption per HH - 2kW at all times of the day
-Supply is from a coal plant with peak steam temp of 600 °C and discharge of 45 °C
-Real Efficiency of converting heat > energy is 60% of the Carnot efficiency.
-Power station uses coal with content of 30 GJ/tonne and a GG emission content of 100kg of Co2 per GJ of energy.
-Transmission lost b/w station and town is 10%

What is the energy capacity for the town?
What is the energy capacity of the power station?
How much energy is produced from the electrical power station in one day?
What is the REAL and Carnot efficiency of electricity generation?

2. Sep 15, 2011

### Zryn

I'm not quite sure about the word 'capacity', since the town isn't storing energy, so I will assume it means 'demand'.

You are given the following:

-Town Population - 100 000, average 4 people per household
-Average consumption per HH - 2kW at all times of the day

Given the population and the average people per household, you can figure out how many households there are.

kW is a SI unit that can be broken down into base units, one of which includes the SI unit for energy. Given that you are asked to find energy, and given kW, you may need to manipulate the kW unit. Do you know how to do this?

Given the consumption per household of 2kW at all times and the number of households, you can figure out the energy demand for the town at all times.

I believe this is the style of analysis asked for, taking in a number of real world inputs and converting through the system to find the Energy.

As a side note, steel deforms at around 540 degrees Celsius, so a peak steam temperature of 600 degrees Celsius running through steel pipes might have interesting results.

3. Sep 15, 2011

### SteamKing

Staff Emeritus
Steam generators (boilers) are constructed from special alloy steels which are designed to retain strength at high temperature. Central stations routinely operate at 600 C.

4. Sep 15, 2011

### Zryn

I suppose there are a thousand different power station designs and grades of steel, though the ones that I have worked at (which are all at least 40 years old) have all manner of temperature alarms between the furnace steam outlet and the IP turbines to ensure the system cuts out before or shuts down at 538 degrees. Old school maybe?

5. Sep 15, 2011

### rude man

I agree, "energy capacity" is a weird choice of words. Should be "power demand" for the town and "rate of heat generated" for the station.

Work backwards. Start with the power required of the households, add for transmission losses, then the two sources of efficiency losses, finally arriving at the power furnished by the coal.