Question to the HM Treasury:

To ask the Chancellor of the Exchequer, what timescales her Department uses to assess public investment in energy infrastructure in (a) oil and gas, (b) wind, (c) solar, (d) hydropower and (e) nuclear.

The costs and benefits of a proposal should be calculated over its entire lifetime. The Green Book states that an appraisal period of 60 years is a standard measure for infrastructure projects. However, it is customary for departments to discuss and agree a suitable appraisal period with the Treasury in advance, based on the lifetime of the proposal.