Fossil Fuels
 

 

Carbon dioxide emissions from the consumption of fossil fuels

Consumption of fossil fuels is the dominant source (>99%) of greenhouse gases in Rhode Island. Because of the importance of this source and in order to give a more complete picture of the trends in fossil fuel emissions, this section of the inventory was compiled over a longer time period than required by the Workbook. Emissions data for the consumption of all fossil fuels were compiled for the 11-year period of 1986 1996, based, with one exception, on the Energy Data Report for Rhode Island for 1996, provided by the Energy Information Administration (EIA). The one exception is for emissions from electric utility emissions.  For these, the EIA data were found to be in error, and data obtained from the RI Public Utilities Commission was used instead, as reported in the section on Electricity Generation.  The EIA reports fuel consumption by sector (residential, commercial, industrial, transportation and electric utility), and within each sector by fuel type. Following Workbook procedures, these data were converted into metric tons of carbon equivalents (MTCE) for all emissions.

The Fossil Fuel Emissions Table lists emissions by sector for 1990 and 1996, and accompanying figures show the eleven-year trends in emissions by sector. Note that 79% of the increased emissions between 1990 and 1996 result from an order of magnitude increase in emissions from electric utilities.  Note also that this section of the inventory reports only carbon dioxide emissions.  Emissions of nitrous oxide and methane (from mobile sources) are reported separately.

Fossil Fuel Emissions by Sector, in MTCE

1990

1996

1990-96

Sector

MTCE

MTCE

MTCE Increase

Increase

Residential

556,441

 

697,861

 

141,420

25%

Commercial

368,972

482,846

 

113,874

31%

Industrial

152,399

190,948

 

38,549

25%

Transportation

1,020,868

1,071,085

50,217

5%

Electric Utility

120,829

1,430,669

1,309,840

1084%

Total

2,219,509

 

 

3,873,409

1,653,900

75%

 

Note that the emissions from fossil fuel combustion listed in the table above are only those emitted directly in Rhode Island, and specifically do not include indirect emissions from the generation of electricity consumed in Rhode Island, but generated outside of the state.  Most greenhouse gas emission reduction strategies will need to consider both direct and indirect emissions, and for this purpose, the following chart reports total emissions - i.e. emissions from the generation of electricity consumed in the various sectors are included in this chart..  

 

Emissions for 1990 have particular significance, because that is the base year chosen for setting emissions reduction goals. The figure shows that 1990 emissions were significantly lower than any other year in the 86 96 period, a result of a temporary dip in distillate fuel consumption and a long-term decline in residual fuel use. (See the Emissions by Fuel Type figure). Emissions increases after 1990 result from a strong increase in use of natural gas in the utility sector and a return to pre-1990 levels in distillate fuel use.

Although data obtained from the RI Public Utilities Commission, together with certain reasonable assumptions,  allowed the estimation of carbon dioxide emissions from the generation of electricity consumed in the various sectors, we did not have the information we would have needed to identify the fuel types used for this generation.  Therefore, we have used data provided by the EIA, which we know in at least one case (natural gas supplied to the industrial sector) to be low, because they were the only data available.  As expected, the total emissions shown in the following charts are therefore somewhat lower than those in the preceding chart. . 

 

The dip in distillate fuel use in the residential sector in 1990 (14.9 TBTUs, compared to an eleven-year average of 18.6) seems to be the result of an abnormally low number of heating-degree days for that year. (See Annual Degree Days, 1986 1996)

 

 

The only comprehensive source of fossil fuel consumption data available to us was that provided by the EIA. EIA data are compiled from surveys of the owners of distribution systems, and apparently are subject to significant uncertainty. In the one case where we were able to obtain independent reliable data against which EIA data could be cross-checked (natural gas consumption by the industrial sector), the EIA data were found to be seriously in error. We therefore caution that the data supplied in this section may have considerable uncertainty however the EIA data are all that are available, and there is no alternative to using them.

Analysis of emissions from fossil fuel combustion for the period 1986 - 1996

Because of the dominance of the inventory by emissions from fossil fuel combustion , we have prepared a variety of figures, showing the various combinations of fuel types and emissions sources. The charts below are linked to larger versions in the Fossil Fuel appendix.  They show the breakdown by fuel type (Distillate Oil, Residual Oil, Gasoline, Diesel Fuel, Natural Gas) within four sectors of the economy (Residential, Commercial, Industrial, Transportation) (the right column) and within three fuel types, a breakdown by economic sector (the left column).  Again, please note that emissions from the generation of electricity are not included in these charts.

 

 


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Greenhouse Gas Inventory for Rhode Island  September 2000 

Prepared by Brown University Center For Environmental Studies