How much seasonal energy storage?

If most of the world's energy came from wind & solar, how much energy storage would we need to smooth out the seasonal variations?

Analysis needed

Get data on solar

Case study needed: Rooftop solar panels, how much power output for each hour - data collected over the course of a year or more.

Get data on wind

Case study needed: Power combined from a large number of wind turbines dispersed geographically but still close enough to share the same power grid. Hourly data collected over the course of a year or more.

Get data on energy demand

Hourly data collected over the course of a year or more:

Base demand, excluding heating
Heating demand
- Ideally, the case study's geographical location should be similar to the wind & solar case studies

Run it through a simplified computer model

To implement this, I started writing some code: Code:how-much-energy-storage.c

Scenario

An intermittent mix of wind & solar electricity
Short-term energy storage: Batteries
Longer-term energy storage: Hydrogen gas

Logic for each point in time

Use of the solar+wind electricity:

1st priority: Meet base demand (not including heating)
- If not enough, take from batteries
- If not enough, gotta use fossil fuels :( or nuclear :)
2nd priority: Charge batteries
3rd priority: Use surplus electricity for heating
4th priority: Produce hydrogen gas

If needed, burn hydrogen to provide the rest of the heating.

If not enough, gotta use fossil fuels :( or nuclear :)

Input parameters to tweak

Overall supply/demand ratio
- Default value: 2
- Definition: {total solar+wind energy produced over time} / {total energy consumed over time}
Solar/wind ratio
- Default value: 1
- Definition: {total solar energy produced over time} / {total wind energy produced over time}
Battery capacity discussion Should this be specified in kWh, or in {hours of {total energy consumed over time} }?

Results to look at

What percent of energy demand gets covered by renewables
Maximum hydrogen gas stored at any given time