It would be a nice addition but I have to agree it would be easier to add as an expansion to the existing elements rather than give it its own category. It would need its own opposite as well, bringing the count to 14 elementals. I guess tech would represent order and stasis which would be opposite the wild and chaotic entropy.
12 elements is more than enough. Just add "technology" as a property of one of the elements. Gravity, maybe, as it already has little bits of that - armoured creatures and that sort of thing. Or maybe spread it across all the colours. Light could definitely make use of lasers, for example.
Holy beams, Batman! Miracle 2.0 just nuked you for 99 damage! (Sorry, just had to...)
That is, if technology would even fit anywhere in the concept of "elementals dueling for whatever reasons they may have".
An off topic bit of trivia for you guys. And feel free to Google a lot of this.. it's really interesting.
The original elements were air, water, fire, and earth/metal/wood. Differences in the last element(s) depended on where you lived. Earth is a western idea whereas metal and wood are more Asian in theme. Following that example, life and death are not really elements as much as forces of nature. Entropy, time, etc. are also pushing the envelope.
Newer schools of thought ("newer" being within the last 800 years or so) have added various elements such as lightning, mist, and clay. These are not necessarily original elements but more like variants of the originals, for example lightning being a combination of fire and air (burning air, get it?). I believe this falls under the blanket "animism" category relating to all things having a spirit of their own or some sort of spiritual realization.
The most recent additions to the idea have come about in the mid 20th century. With the discovery of the atom and the advent of various nuclear devices have come more questions and interpretations. Added to the list of elementals we now find such things as radiation, plasma, and cosmic/cosmos (meteors, comets, stars, etc) elements. Radiation is an obvious side effect of technology as it rarely occurs in great amounts outside of human intervention. These new thoughts have also expanded to include time, space, dimension, and all forms of energy (including light) as their own element with some sort of mystical (spirit) representation.