What are the reasons why a coal fired plant will operate less efficiently than a gas fired plant?

Answer 1

try this from: http://www.nei.org/index.asp?catnum=2&catid=262

Economic Efficiency is the most important measure of efficiency because it measures how a plant uses scarce resources and what the value of those resources is.

Economic Efficiency is measured using production cost.

Production cost is the cost of operating the plant—including fuel, labor, materials, and services—to produce one kilowatt-hour (kWh) of electricity. In 2005, nuclear power had the lowest production cost of the major sources of electricity, with production cost of 1.72 cents/kWh. Coal had a cost of 2.21 cents/kWh, natural gas 7.51 cents/kWh, and petroleum 8.09 cents/kWh. Hydro had a production cost of 0.83 cents/kWh, wind 0.04 cents/kWh and solar 2.17 cents/kWh.

Answer 2

Coal is actually more efficient than gas. That's why there are so many coal plants - 20 years ago, they used to just burn the natural gas off & not use it at all.

Natural gas makes burns to make carbon dioxide and water - and if you look up the heat of reaction, you'll find out that the water releases less energy when it's formed. The end result is that, because it needs more air per BTU (or watt), the gas plant will be about 4 - 5 % less efficient.

Gas is, however "cleaner" than coal - was that what you meant?

Answer 3

Gaseous fuel needs only to be dry and filtered before combustion in a furnace or boiler.

Coal needs to be mined, graded and sorted to ensure no stones or unwanted substances are mixed with it.
The combustion of coal then requires large transport vehicles to deliver to the plant.
The coal is then pulverised to virtual powder for better ease of combustion.
Combustion of coal produces more pollution in the form of noxious gases, smoke and deposits of ash...etc.
Not an easily controlled combustion process...Overall, not as efficient as gas.

Answer 4

Coal fired plant has a few more maintenace prone areas :
1. coal mill area
2. ash handling area.
3. tube bank -- ash deposition/erosion and tube leakage
Frequent failure of these systems make coal plants less efficient in operation at lower plant usage factor..

Answer 5

You need only look at the heat of combustion (heat value)number of the fuel you're comparing. The higher this number the more energy it packs per unit weight (BTU/lb) or unit volume (BTU/gallon). Hence the higher the number the less pounds of fuel you'll need to produce a given amount of energy the more efficient the plant will be on a pound-fuel/energy produced ratio. Go here for a more specific explanation. http://en.wikipedia.org/wiki/Heating_value

Hope this helps