How would the footprint of a shale gas operation compare with the footprint of other ways of delivering a similar quantity of energy?

There are many dimensions to a "footprint". In this blog post, I'll look at land area, vertical height, and vehicle movements.

I'll compare a shale gas pad (which might produce 0.9 billion cubic metres of gas over 25 years) with a 174-MW wind farm and a 380-MW solar park, both of which would deliver roughly 9.5 TWh of electricity over 25 years ­– the same amount of energy as the chemical energy in 0.9 billion cubic metres of gas.

In this table I've highlighted in green the "winning" energy source for each of the footprint metrics.

The total land area of the facility is smallest for the shale gas pad, and largest for the wind farm. The land area actually occupied by stuff is smallest for the shale gas pad, and largest for the solar park ­– the wind farm has lots of empty land between the turbines, which can be used for other purposes.

In terms of visual intrusion, the wind turbines are the tallest, and could be seen from a land area of between 52 and 170 square km, depending how they are laid out. (To roughly estimate an area of visual influence, I computed the land area within which the drilling rig or a wind turbine would be higher than 3 degrees above the horizon, assuming a flat landscape.) By this measure, the shale gas pad creates the least visual intrusion. Moreover, the drilling rig might be in place for only the first few years of operations at the shale gas pad. The solar panels are the least tall, but the solar facility occupies 450 times as much land area as the shale gas pad. (I've assumed that the wind farm and solar parks wouldn't require any additional "intrusive" electricity pylons.)

When it comes to truck movements, all three energy facilities require lots! I've assumed that solar panels are delivered at a rate of 800 (originally 400^*) panels per truck; for the wind farm, my estimate is dominated by the delivery of materials for foundations and roads at 30 tonnes per truck; the estimates for the shale gas pad are from DECC's recent Strategic Environmental Assessment and from the Institute of Directors' report "Getting Shale Gas Working". The shale gas pad might require the fewest truck movements, if all water is piped to and from the site. But if water for the fracking is trucked to and from the site, then the shale-gas facility would require the most truck movements.

What can we take from these numbers? Well, perhaps unsurprisingly, there is no silver bullet ­– no energy source with all-round small environmental impact. If society wants to use energy, it must get its energy from somewhere, and all sources have their costs and risks. I advocate deliberative conversations in which the public discuss the whole energy system and look at all the options.

Thanks to Jenny Moore, Martin Meadows, and James Davey for helpful discussions.