That’s the headline for my latest piece in Inside Story, looking at the implications of zero interest rates for renewable energy sources like solar and wind. Key para

Once a solar module has been installed, a zero rate of interest means that the electricity it generates is virtually free. Spread over the lifetime of the module, the cost is around 2c/kWh (assuming $1/watt cost, 2000 operating hours per year and a twenty-five-year lifetime). That cost would be indexed to the rate of inflation, but would probably never exceed 3c/kWh.

The prospect of electricity this cheap might seem counterintuitive to anyone whose model of investment analysis is based on concepts like “present value” and payback periods. But in the world of zero real interest rates that now appears to be upon us, such concepts are no longer relevant. Governments can, and should, invest in projects whenever the total benefits exceed the costs, regardless of how those benefits are spread over time.