Beginning July 1, a 4% rate drop will mean an average monthly saving of about $2 to $5 for Nashville Electric Service customers. The rate decrease is the result of lower fuel and purchased power costs. The Tennessee Valley Authourity began using the Fuel Cost Adjustment in October 2006 after experiencing a spike in fuel costs caused by Hurricanes Katrina and Rita the previous year. July’s upcoming 4% decrease combined with the 6% decrease in January and the 5% reduction in April has lowered the Fuel Cost Adjustment by 15% in 2009. About 60% of TVA’s power supply comes from fossil fuels used to make electricity – coal, oil and natural gas.