Sidhe level or in the realm of a 'normal' practitioner?

It is possible for a Mage to set up a spell that will take raw energy of various types and use it to produce Essence. Mostly, this is going to be achieved by feeding that energy type to some external entity who will then 'pay' in Essence... a process which happens for 'most' Essence type conversions as well. For instance, if you want to cast a Fire Bolt... you don't personally have to supply Fire Essence to create a powerful and efficient bolt, instead you use your own 'neutral' Essence from your Well, and one stage of your spellwork is a conversion/exchange with a known Entity. You pay out untainted Essence, the Entity supplies you with Fire Essence. that Fire Essence then serves to fuel the final stages of the spell work.

This is a big part of the 'lore' and establishing oneself as a mage over time that isn't automatic for mutant Mages, Wiz or not. You have to know who these Entities are and contract with them... though, in some cases, its more like day trading and the process has been automated for longer than our sun has been burning. But through research and arrangements, a Mage can find 'better' deals... better exchange rates, etc. But, by default, this is basically a process of reaching out to a Mage who lives on a world where elemental Fire is present and/or Fire Essence is the default/easily available... but the 'neutral' Essence of a Terran Mage is hard to acquire.. and trading. You both get something hard to get (or that you can get at a better exchange rate than trying to force your local Essence type to take on the aspects of a specific nature).

The Sidhe can do these conversions on the fly because, as a result of their being composed of Essence, they don't have a Well in the same sense that humans do. And while sub-types of Essence DO affect them if they hold one regularly... they can do so. Humans? Not so much. Taking in too much of a 'tainted' Essence into the human Well is bad news. And not really usable until the Well filters it down. Sidhe just grab it, convert it, and make use of it. Or, if they want to be efficient, they'll exchange it.. But again, since they can handle the energy without bringing it into their body; they can seem to just do it.

For human Mages, the spell work to turn non-Essence energies into Essence is complex and inefficient (after all, you have to be sustaining the spellwork that does all this more or less all the time if you want it to be effective... and you need another piece of spell for each type of energy you want to grab). Another option would be to create and set this sort of spell into an object. But its never going to be as effective or efficient as what the Sidhe mage can do (or other truly magical species).