Portuguese term (edited): lastro (in this case)

:) Just an idea

or 'underlying supply'.

In addition to trading, Sol Energias provides the following advisory services: (i) assessment of potential savings by migrating to the free market; (ii) management of energy purchase contracts and representation in the CCEE; (iii) management of the underlying energy (lastro) and representation in the CCEE for power generating plants; (iv) planning and optimization of energy contracting; (v) feasibility studies for generating projects; and (vi) assistance for selling power in auctions held by the federal government.
https://www.google.com.br/url?sa=t&rct=j&q=&esrc=s&source=we...

Good to see Matheus purging the site of the always-pointless '(in this case).'

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Note added at 2 days23 hrs (2017-07-23 15:13:56 GMT)
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ANEEL prepares energy auctions in the regulated market in accordance with MME’s guidelines, including the requirement to use the lowest bid as the criteria to determine the winner of the auction.

There are basically four types of auctions: (i) A-3 (once a year – to contract power output or capacity to be delivered three years ahead the auction year); (ii) A-5 (once a year – to contract power output or capacity to be delivered five years ahead the auction year); (iii) renewable sources auctions (auctions carried out to contract power generated exclusively from alternative sources of power); and (iv) reserve energy auctions (carried out to guarantee reserve energy for ***supply*** security purposes).
http://latinlawyer.com/jurisdiction/1003017/brazil