lifeenergy.net, not that much because the .com is available for sale. I could only see some institute/foundation/church/hardcore person that would buy this (like lifeenergyinstitute.net). I'd say high xxx at the most. There's only 1,100 searches a month for the broad match keyword "life energy".
I actually think epromotion.net is pretty good, there's over 100,000 broad match searches for "promotions" and a ton more for coupons. Low xxxx.
ecotrack.net, trademarked term, could be worthless unless trademark owner buys it.