Renewable energy targets should not be set with the gut. If at all, they should be set after careful engineering / economic considerations have been studied.
At the very least, the following factors need to be considered:
- Annual insolation patterns (for at least ten years).
- Annual wind patterns (for at least ten years).
- Annual electricity demand patterns (again, for at least ten years).
Off the bat we know solar does not produce at night. So, does wind somewhat complement solar output or is its contribution mostly random (on an annual basis)?
What types of pairing power plants will be used. Natural gas? Coal? Hydro? Nuclear?
What will be the cost of the electricity produced by the panels / turbines considering the system, not only individual components? (Paring power plants need to be ramped up / down, idled, stopped, started and thus even though their fuel use drops, their fixed costs per kWh increase).
No conventional generating capacity may be retired as at any particular moment during the year there may be no sunlight or wind.
Finally, it needs to be decided beforehand what will be done with unwanted generation: will solar panels / wind turbines output be curtailed or will this energy be dumped (possibly at a negative price) into another jurisdiction?
After all of the above is carefully studied, the ideal "renewable" energy penetration in a grid (annual basis) may be between 0 and 5%.
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