https://www.metaculus.com/notebooks/9826/renewables-forecasting/

Published by RyanBeck on Feb 14, 2022.

In a recent article about solar power, Tom Chivers described how growth in solar power has outpaced many forecasts, as well as the challenges involved in accurately forecasting trends in solar power. Making accurate forecasts about the future of solar is important for understanding what future CO₂ emissions may look like and what our chances of mitigating the effects of climate change are. In this essay I attempt to estimate the bounds of solar and wind growth.

Pieces of the puzzle

The first stage of putting together an energy forecast is to understand the relevant background information. What the different units mean, how different energy types can be compared directly, and what the previous trends look like are all essential if we want to understand the future of electricity generation.

Power and energy

When electricity generation is talked about it can be easy to confuse power and energy. Power is a measure of the rate at which work is being done. Power is commonly measured in watts when discussing electricity generation. Energy is how much work has been done, or the amount of power exerted over time. It is commonly measured in watt-hours, as it is the amount of power (watts) multiplied by the amount of time that power was exerted (hours). We can imagine power as the rate of water flowing out of a hose, while energy is the amount of water in the bucket that the hose is filling after a given period of time.

These are important concepts when talking about electricity generation. When a new power plant is installed it’s usually described in terms of either its power or its capacity. But discussions about what a power plant produces are in terms of energy–such as descriptions of how much energy the plant generated in a given year.