According to the US Energy Information Administration (EIA), energy related carbon dioxide emissions are driven by economic and efficiency trends and changes in the fuel mix. But weather fluctuations, which drive the level of energy use for both heating and cooling, are a very significant factor affecting year to year variation in fossil fuel consumption and their resulting emissions.
EIA’s most recent monthly Short Term Energy Outlook (STEO), issued on 10th October, forecast US energy related CO2 emissions for 2014 and 2015 at 5457 million t and 5436 million t, respectively, both higher than the 2013 emissions level of 5396 million t. The forecasted 1.1% rise in emissions for 2013 relative to their 2013 level reflects a combination of historical energy use data already in hand for more than half of the year and forecasted energy use for the remaining months.
Very cold weather early this year contributed to an increase in total energy use and CO2 emissions for the first six months of 2014 compared with the same period the year before. EIA ran simulations using the STEO model to estimate how much lower emissions would have been had the weather in the first half of the year instead been more like the previous 10 year (2004 – 2013 average). The results show that using this alternative weather scenario, energy related CO2 emissions during the first half of 2014 would have only been approximately 0.4% higher than in the first half of 2013, well below the actual first half to first half emissions increase of 2.7%.
Under the alternative weather scenario, first half energy related CO2 emissions results are approximately 64 million t lower than their actual value of 2737 million t, mainly reflecting lower use of natural gas and electricity for winter heating. The residential sector accounts for approximately 62% of the reduction in natural gas consumption and 86% of the drop in electricity use in the alternative weather scenario, with the commercial sector accounting for most of the remaining difference.
Because natural gas is a major heating fuel, high heating demand may also raise the price of natural gas relative to coal, which effects economic decisions regarding electricity dispatch. Substitution of coal for natural gas in electricity generation increases the amount of CO2 released per kilowatthour (kWh) of electricity generated. These estimates do not include substitution of natural gas for coal related to a possible lower relative natural gas price. However, the estimated 1.8% reduction in total electricity sales in the alternative weather scenario is assumed to be met by a reduction in coal use for electricity generation.
Adapted from a press release by Emma McAleavey.
Read the article online at: https://www.hydrocarbonengineering.com/the-environment/30102014/colder-weather-leads-to-higher-carbon-dioxide-emissions-1533/