As an investor, I have a similar problem. For example, I want to fund the production of wind turbines. If my lifestyle requires 5 kW (peak) of wind turbines, should my wind turbine production assets be capable of producing wind turbines for the 5 kW peak production in 5 years, 10 years, or 20 years?
I also want to fund the production of electrolysis cells as an environmentally friendly way of storing energy for longer terms than few hours. Let's say my lifestyle requires 2 kilowatts (peak) of electrolysis cells. Should my electrolysis cell production assets be capable of manufacturing the electrolysis cells in 5 years, 10 years or 20 years?
Similarly, I want to fund the production of solar cells, too. Let's say I need 2.3 kW (peak) of solar cells for my lifestyle. Should my solar cell manufacturing assets be capable of manufacturing the solar cells in 5 years, 10 years or 20 years?
There's one timeframe you cannot exceed and it's the lifetime of a particular component.
For example, the lifespan of solar cells is around 25 years and approximately the same is true for wind turbines too. The lifespan of electrolysis cells is measured as a function of hours of operation, so the lifetime will depend on how often these components are used.
I generally use a timeframe that is somewhat lower than lifetime of the components. So, for example I currently own enough of Vestas Wind Systems to create 540 watts (peak) of wind turbines per year. Thus, the required 5 kW will be created in bit more than 9 years.
I think this value (less than 10 years) is good, because it is faster than the need to take action on climate change. If the whole energy sector would shift entirely to renewables and clean energy storage within less than 10 years, climate change would not be a problem.
I would recommend using 10 years as the timeframe. It's less than the lifetime of the components such as solar cells, wind turbines or electrolysis cells. It's also fast enough to make a meaningful impact on climate change.