3.3.4 Process and Commercial/Residential Heating
This sector includes the burning of fossil fuels to provide energy to operate large industrial facilities like oil refineries, steel mills, cement kilns and the combustion of natural gas and oil to heat businesses and homes. This is responsible for about 20% of the GHG forcing, but receives little attention. Fuel switching to natural gas has been used in some areas (86), but otherwise little has been done to reduce GHG emissions.
A complete switchover to electric heat produced by power plants from which the GHG emissions are controlled would reduce the impact from the commercial/residential sector, but this is dependent on how electricity will be produced in the future. Industries can make some changes to their processes today to lessen GHG emissions, but completely GHG-free industrial processes are once again dependent on when the hydrogen economy takes over, certainly not before 2050.
3.3.5 Food Production and Landfill Emissions
Food production and landfill emissions account for about 25% of total anthropogenic GHG forcing, mostly due to methane emissions from livestock and rice production and decaying garbage with some from nitrous oxide (13). Some methane is also released due to gas venting, leaks from pipelines and from coal mining. Reduction of methane and nitrous oxide emissions from food production seems highly unlikely in the short term. Until livestock can be bioengineered to not produce methane in their digestive processes, they will remain a significant source of GHG emissions. Because nitrogen-based fertilizers are a critical part of food production, agriculture will continue to be a large source of nitrous oxide from fertilizer degradation processes in soil.
There is no practical way to capture methane and nitrous oxide emissions from non point sources like rice paddies and croplands. A few efforts have been made to capture methane from animal waste lagoons, but methane capture is too expensive to be widely used. Capturing methane from landfills is also possible, but not widely used.
A proposal to dispose of U.S. crop residue from corn, soybeans and wheat (240 million metric tons carbon equivalent on an annual basis) in the Gulf of Mexico (87) failed to consider anaerobic decomposition that would release large quantities of methane, plus the fact that this residue supplies nutrients to the soil that would eventually be depleted if disposed of in this way.
Some work has been carried out suggesting that conventional farming practices could be modified to reduce carbon dioxide emissions due to plant decay. These changes include no till farming, increasing crop rotation, reducing soil erosion, planting high residue crops like corn and wheat and planting cover crops (53, 56, 75, 88). However, this is at too early a stage to predict any future success. Attempts to count carbon sequestration occurring from existing farming practices towards meeting targets like those of Kyoto are misleading and meaningless.
