One fuel is not like another - at least when it comes to carbon dioxide emissions. Burning lignite, for example, produces around twice as much carbon dioxide in relation to its energy content as burning natural gas. Natural fuels such as peat and wood also have very high specific emissions if they are not used sustainably. Deforestation therefore has a doubly negative effect on the climate. If the amount of wood burned is limited to the amount that can be regrown, its use is neutral, since wood binds just as much carbon dioxide from the atmosphere as is later released during combustion.

If the fuels are used to generate electricity, carbon dioxide emissions increase opposite proportional with the power plant efficiency. The worse the efficiency of electricity generation, the greater the electricity-specific emissions. For example, if lignite from the german region Lusatia is burned in a power plant with an efficiency of 35 %, 1,14 kg of carbon dioxide is produced per kilowatt hour of electrical energy (kWh_el). In a natural gas combined cycle power plant with an efficiency of 60 %, as another example, only 0,33 kg of carbon dioxide is emitted per kWh_el.

Replacing lignite-fired electricity with electricity from natural gas can therefore save over 70% of the direct carbon dioxide emissions. In order to properly understand this benefit, the upstream chain emissions and the resulting greenhouse effect must also be taken into account.

Methane, as the main component of natural gas, has a particularly high global warming potential GWP₂₀: Over 20 years of being released to the atmosphere, methane drives global warming by a factor of 84 compared to the same amount of CO₂ (IPCC WG1AR5, p.714). Thus, the transport leaks have a high impact on the total GWP of the Natural Gas based power supply and therefore must be considered. Independent surveys of current methane emissions from gas production, transport and use are not yet available for Germany. The following calculation serves as an illustration of the greenhouse effect of natural gas in electricity production, including fugitive methane emissions.

For long-term climate protection, only emission-free energy supply, based on renewable energies and sustainably biomass is an alternative. By getting out of natural gas-fired power generation, it is possible to stop the methane leakage emissions and therefore reduce the global warming potential.

Fuel	Emissions in g CO2/kWhPE	Emissions in g CO2/MJPE
Wood1)	0	0
Wood2),3)	367.6	102.1
Lignite3)	398.7	110.8
... Lusatia3)	399.6	111.0
... Central Germany3)	371.6	103.2
... Rhineland3)	407.3	113.1
Peat3)	366.5	101.8
Hard coal3)	338.2	93.9
Gasoline3)	263.	73.3
Fuel oil3)	266.5	74.0
Diesel3)	266.5	74.0
Crude oil3)	263.9	73.3
Kerosene3)	263.9	73.3
Liquid petroleum gas3)	238.8	66.3
Natural Gas3)	200.8	55.8

Fuel type	Power Plant Efficiency	direct CO2-­emis­sions1)	Emis­sions incl. upstream chain2)
	%	g CO2/kWhel	g CO2‑eq/kWhel
Lignite
old	343)	1173	1200
modern	483)	831	850
mean	383)	1049	1073
Hard coal
old	363)	939	1051
modern	513)	663	742
mean	393)	867	970
Natural Gas
new (turbine)	39,2	512	624
new (CCGT)	59	340	415
mean	56,14)	358	436

The calculation takes into account direct emissions of CO₂ and other greenhouse gases as CO₂ equivalents („CO₂‑eq“) as well as different leakage losses.

Leakage losses	Diffuse emissions1)	Diffuse and direct emissions2)
	g CO2‑eq/kWhel	g CO2‑eq/kWhel
0%	0	358
1%	108	466
2%	216	574
3%	324	682
5%	540	898
10%	1081	1439