Tennessee seeks 200 MWac of renewables + energy storage


The Tennessee Valley Authority’s (TVA) 2019 Integrated Resource Plan included the potential for 3-8 GW of solar power through 2038. Some thought this number was a bit soft with the amount of flexible generation – specifically a number of large hydropower plants – the region has, and the amount of fossils still needing be shut within the utility region. The company did note that they’d have a new solar program in place by 2020.

On April 1, the Tennessee Valley Authority (TVA) issued a Request for Proposals (RFP) for 200 MWac of renewable energy resources, with a strong interest in energy storage. The RFP requests respondents submit proposals with 12-, 15- and 20-year delivery periods. The deadline to submit questions is May 1, with proposals due by May 15 and selection of projects expected in October. The projects must be online by October 31, 2022.

The document notes the utility is interested in energy storage along with renewables, and works to create a financial structure that will support the projects. Noted in above image, the projects will receive a 2% escalator for all revenue. A standard dollar per megawatt-hour price will be offered for the electricity, while the energy storage will receive an additional dollar per kilowatt per month capacity payment, plus an operations and maintenance fee for the energy storage system. The pricing will include  all energy, capacity, transmission, ancillary services, and environmental attributes from the plant.

The program seeks projects at least 2 MWac in capacity. In terms of sizing the energy storage, TVA requests:

energy storage should be sized to provide sufficient storage capacity equal to the greatest amount of energy to be provided for a continuous four-hour discharge during a 4-hour period with 380 annual cycles

The projects must specify whether the storage will be AC or DC coupled, whether or not it will have flexibility in charging/discharging periods, while nothing the storage can be charged by either the grid or the attached renewable energy facility (however, ITC considerations will influence this).

When pricing the electricity, TVA put out the below table denoting both seasonal and time of day variances in the valuation of the electricity generated. The RFP notes that TVA prefers the electricity pricing from proposals to include the seasonal variance, although it seems they might accept an average price.

The seasonal document strongly supports the summer months of July & August, around the clock. Also supported are the exact opposite months – January & February, though the numbers aren’t as strong. The shoulder periods of spring and fall see discounted pricing.

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