With the launch of the Energy Market Offer Flexibility Project during December 2014, dual-fuel generators are now able to submit supply offers that specify the percentage of each fuel they plan to use during the upcoming hour—called “blended offers.” The market changes are designed to give generators the flexibility to represent their cost for each fuel in their supply offers, helping to ensure that when they must switch fuels, their costs are accurately represented—an incentive for them to perform as needed.
As an added benefit, the inclusion of blended offers provides better insight into the fuels dual-fuel units are using and thus more accurate representation of the amounts of electricity generated by each type of fuel in New England. This June, the ISO updated its web service that provides the data for ts real-time fuel mix chart (available on the iso-ne.com homepage, in ISO Express, and in the ISO to Go mobile app), its Daily Generation by Fuel Type report, and other market reports to reflect this enhanced data, concurrent with the December 2014 market change.
Most of the time, dual-fuel units do not submit blended offers; they generally use their least expensive fuel (usually natural gas in gas/oil units). Blended offers are most likely to occur when market or operating conditions warrant the fuel switch. For example, during tight winter conditions, a natural-gas-fired plant may switch to oil if it has insufficient gas supply or if the price of gas becomes higher than oil. The enhanced data would be reflective in the real-time fuel mix chart during these times.