Energy saving technology and energy service price I want to assess the effects of energy saving technologies on output growth using time series data. My work would benefit from time series data on patents for energy saving innovations, but this is hard to find. I have time series data on energy service prices (not energy prices), which I am thinking of using as a proxy for energy saving technologies. Energy service prices appear to have declined over time and this is due to the improvement in energy technologies, mainly. Thus, I assume the energy service price data reflects the improvements in energy technologies.

Do you think the idea of proxying energy technologies with energy service prices is appropriate in an empirical analysis? 

Edit: Price of energy refers to the price of energy carrier, say oil. Energy service price refers to the cost of providing an energy service, say heating or lighting etc.
A problem with using energy service prices is that they might reflect competition conditions (e.g. monopoly/oligopoly, or the big six in the UK) rather than the true cost of energy to firms. 

A problem with using energy prices is that they might reflect demand and supply issues. For example, no one would say that the drop in oil prices from 140 to 50 was due to technological improvement. Instead, it was driven by a shale oil revolution, and perhaps geopolitical aspects.