Emissions from Renewable Energy

From ClimateWiki

The following is a detailed outline of emissions produced by renewable energy sources and how they compare to other resources.

Many individuals are under assumption that renewable energy resources are ideal because they do not release emissions. This is not the case. Though renewable resources release less greenhouse gas emissions than nonrenewable sources, the renewable energy sources that are being most prominently promoted are not as efficient (or cost effective) as they are being represented.

Life-cycle emissions from renewable electricity generation range from 9 to 41 mT CO2-e per MWh, with wind and hydropower at 9 to10, and photovoltaics at 32.

Fossil fuel-burning plants, in contrast, ranged from about 440 mT CO2-e per MWh for natural gas combined cycle turbines and up to 1,050 for some coal plants.

Nuclear Power

Nuclear power has much lower life-cycle greenhouse gas emissions than fossil fuels, but a higher rate compared to the leading renewable technologies being used and promoted.

On grounds of greenhouse gas emissions alone, nuclear power is a big improvement over fossil fuels, with about 15 percent of the emissions (per MWh) of efficient natural gas-burning plants.

Yet, wind and hydro-power have about 15 percent of the emissions of nuclear plants; photovoltaics may have half the emissions of nuclear power.

Renewables And The Impact On Environment

The likely life-cycle emissions (taking into account fuel cultivation, harvesting, collection, transportation and processing, as well as power plant construction, operation and decommissioning) from main renewable energy technologies and conventional electricity generation is shown in the Table.

The results are purely indicative but show the variations and relative differences between the various fuel inputs.

Life-cycle emissions from renewable energy use are small compared with those from fossil fuel plants.

Table - Life cycle air emissions from renewable energy (g/kWh)

Energy Crops: Current Practice

CO2 17-27

SO2 0.07-0.16

NOx 1.1-2.5

Energy Crops: Future Practice

CO2 15-18

SO2 0.06 - 0.08

NOx 0.35-0.51

Hydro: Small Scale

CO2 9

SO2 0.03

NOx 0.07

Hydro: Large Scale

CO2 3.6-11.6

SO2 0.009-0.024

NOx 0.003-0.006

Solar: Photovoltaic

CO2 98-167

SO2 0.20-0.34

NOx 0.18-0.30

Solar: Thermal Electric

CO2 26-38

SO2 0.13-0.27

NOx 0.06-0.13

Wind

CO2 7-9

SO2 0.02-0.09

NOx 0.02-0.06

Geothermal

CO2 79

SO2 0.02

NOx 0.28

References

http://realclimateeconomics.org/wp/archives/795

http://electrical-engineering-portal.com/renewables-and-the-impact-on-environment