1.
i. If the energy content of high pressure steam can be assumed to be 3.0 GJ tonne-1 and the steam is produced with a thermal efficiency of 90%, how many GJ of gas are needed to make one tonne of steam.
ii. If 20 million cubic metres of natural gas is used per day calculate how many tonnes of steam it produced per day
The calorific value of natural gas is 39 MJ m-3.
2. If a 1 gigawatt solar thermal steam plant was used instead of natural gas
Total greenhouse area 1.0 km2
Incident solar radiation 5.6 kWh m-2 day-1
Steam production 1000 tonnes per day
i. Work out the average incident solar energy falling on the total greenhouse area in MWh per da
ii. Using the figure for the energy content of steam of 3.0 GJ tonne-1 show that the overall solar thermal collection efficiency of the plant
Remember 1.0 kWh = 3.6 MJ.
iii.Using your answer from part 1i calculate how many GJ of gas should be saved each day by this plant.