Question

1) The power company is considering installing a new plant using natural gas as fuel to generate the same amount of energy. If the natural gas to be used has an energy capacity of 43MJ/m³ (mega joules per cubic meter of gas)

a) Estimate the volume of natural gas needed in m3/yr.

b) Calculate the annual emissions of criteria pollutants including SO₂, NO_x, PM and green house gasses including CO₂ and CO using the appropriate emission factors given in the table below.

2) Given the cost of Bituminous coal is $750/MT and natural gas is $25/m³ calculate the operating costs for the plant per year.

3) Based on the emission estimates and costs which fuel would you recommend as the best fossil fuel power source for the plant? Why?

Pollutant	Anthracite coal	Bituminous coal	Fuel oil	Natural Gas
CO2 (g/GJ)	94600	101000	77400	56100
SO2 (g/GJ)	765	1361	1350	0.68
NOx (g/GJ)	292	183	195	93.3
CO (g/GJ)	89.1	89.1	15.7	14.5
Particulate matter (g/GJ)	1203	3254	16	0.1

Answer 1

A power plant with en efficiency of 75% combusts 700,000 metric ton (MT) of bituminous coal per year to generate electricity. It has been establish that this type of coal has the capacity to generate electrical energy at 21 GJ/MT.

      How much energy in GJ (giga joules) does this plant generate in one year?

energy in GJ (giga joules) does this plant generate in one year=75/100*21GJ/MT* 700,000 (MT)=11025000GJ/year

a) If a new plant using natural gas as fuel to generate the same amount of energy=11025000GJ/year

And energy capacity of natural gas =43MJ/m³=43*10^6 J/m3=43*10^6/10^9 GJ/m3=0.043 GJ/m3

So volume of natural gas needed in m3/yr=11025000GJ/year / 0.043 GJ/m3=256395348.84m3

b) the emissions of criteria pollutants=(56100+0.68+93.3+14.5+0.1)=56208.58 g/GJ

annual emission =56208.58 g/GJ*11025000GJ/year=619699594500 g/yr

2)cost of Bituminous coal = $750/MT

operating costs for coal the plant per year=$750/MT*700,000 (MT/yr=$525000000

operating cost for natural gas is $25/m³

operating costs for the natural gas plant per year= $25/m^3* 256395348.84 m3/yr=$6409883721 /yr

3)operating costs for the natural gas>operating costs for coal the plant per year

Moreover, emission estimate of pollutants by natural gas=619699594500 g/yr

emission of pollutants by bituminous coal=(101000+1361+183+89.1+3254)=105887.1 g/GJ

emission estimate of pollutants by bituminous coal=105887.1 g/GJ * 11025000GJ/year=1167405277500 g/yr

But emission estimate of pollutantsby bituminous coal >>>emission estimate of pollutants by natural gas

So natural gas must be a better fuel.