Authors' headline elasticities are the 2SLS estimates which correct for simultaneity of the average-revenue price; OLS shown 'for comparison only' || 'These results relate to the 2SLS estimates. It is also interesting to note the stability of the parameter estimates across the two estimators.' (p.83); 'OLS estimates with the adjusted data are presented for comparison only, as the gauge of the potential distortion which would result from ignoring the simultaneity.' (p.83)
Smith, V. K. (1980): “Estimating the Price Elasticity of US Electricity Demand.” Energy Economics 2(2), 81-85