Word Document for Answers to Coal Exercises

Exercise COAL.1

Open exercise sheet “Annual_Coal_Exercises.xlsm”. This is a blank questionnaire.

Supply of primary coal products

a) Fill in the Coal table of the AFREC questionnaire with the data below. Messages will appear to the right of the table as you enter the data. These messages help check whether the data entered meets the statistical difference rules of the table.

In 2009, your country:

 Produced 1,000,000 tonnes of bituminous coal (net calorific value 24 380 kJ/kg) ● Imported a total of 1,500,000 tonnes of anthracite coal (net calorific value 26 120 kJ/kg) ● The opening stock level of coal was 220 kt. ● The closing stock level of coal was 180 kt. ● Calculate and report the stock change.

Stock change should be equal to +40 kt (stock draw)

b) 2000 kt of the coal supply is used in a coal to liquids plant. This plant produces 150 kt of jet kerosene and 350 kt of gas/diesel oil. The jet kerosene is used as international aviation bunkers and the gas/diesel oil is used in the transport sector.

The remaining coal is used for power generation.

How would you report this in the Coal and Oil tables?

c) Your supervisor at the coal-to-liquids plant asks you to calculate the transformation efficiency of the coal-to-liquids plant. How would you proceed?

Efficiency is calculated as Output divided by Input when both have been converted to energy content in net calorific values.

d) What information are you still missing to complete this calculation?

The efficiency cannot be calculated without knowing the proportion of bituminous coal versus anthracite, since the energy content of the inputs cannot be derived.

Exercise COAL.2

Efficiency of the coal-to-liquids plant

a) Your supervisor at the coal-to-liquids plant provides you with the following information.

In 2009, your coal-to-liquids plant consumed:

1 ● 1,500 kt of bituminous coal ● 500 kt anthracite

What is the plant efficiency using the NCVs provided above for the coals and the default calorific values for the oil products provided in the Oil table? What is the weighted average net calorific value for production of non-crude oil products?

Outputs = (150 kt *44.6 TJ/kt) + (350 kt * 43.3 TJ/kt) = 21 845 TJ

Inputs = (1,500 kt * 24.38 TJ/kt) + (500 kt * 26.12 TJ/kt) = 49 630 TJ

Efficiency = 21,845 TJ/49,630 TJ * 100 = 44%