Eq 4 is the author's initial/central log-log P2SLS estimate; Eqs 7-8 are robustness variants adding (LEEP)^2. Author states all three are 'entirely compatible', so Eq 4 (-0.86) is the headline own-price elasticity || 'The result for the variable ELPRjt implies that an increase of 1% in the real unit price of electricity would reduce per customer residential electricity consumption by 0.86%.' (p.1501)
Cebula, R. J. (2012): "US residential electricity consumption: the effect of states’ pursuit of energy efficiency policies." Applied Economics Letters, 19(15), 1499–1503.