Grantham has assumed a 0.2% boost to growth from fracking over 18 years, forecasting up to 2030.

This claim is about Grantham's own forecasting assumption. True: GMO/Grantham publications or interviews from around December 2012 show that his long-term US growth forecast added about 0.2 percentage points a year for fracking over an 18-year horizon, running to about 2030. Mostly true: the 0.2% boost appears in his forecast but the horizon is stated a little differently (for example 2012 to 2030 counted as 17 or 19 years), or the boost is applied to a closely related measure (such as GDP growth versus productivity growth). Mixed: his forecast credits fracking with a boost but the size or the horizon differs a lot from 0.2% over 18 years. Mostly false: his forecasts mention fracking only as a qualitative factor, with no figure like this. False: his published forecast models from that period give fracking no positive adjustment, or give it a clearly different figure.

Set before the research began.

1. E1 Why the global economy may be doomed to lower growth—maybe forever Quartz (qz.com) · 1 August 2013

   “For his part, Grantham predicts that fracking and natural gas will end up producing cheaper energy, which will give the economy a 0.3%-0.5% boost over the next new years.”

The only evidence is E1, a Quartz article from August 2013, eight months after the claim. It reports that Grantham predicted fracking and cheaper natural gas would give the economy a 0.3%–0.5% boost, over a period the garbled quote gives as "the next new years". No GMO or Grantham publication or interview from around December 2012 is provided to show whether his forecast then added 0.2 percentage points a year over 18 years to 2030. Because the later figure may reflect a revised view and does not describe his forecast as of the claim date, the evidence does not settle the criteria.