Wind and solar gain priority access to the grid because they do not incur the full cost of supplying their energy. Costs of increased grid construction, backup generators, reserve capacity and ancillary services are not accounted for in their supply. The induced costs and inefficiencies in the coal plants may require significant subsidised costs as is currently the case in Western Australia.
In the following image key elements are:
In the case of the AEMO Integrated System Plan Fast scenario in 2042 the system is steadily becoming more difficult to manage and 21% of the wind and solar energy is spilled or curtailed.
Gas and coal generation has now exited the market. Storage has been increased to 5.1GW of batteries and 21GW of pumped storage. Even at these extraordinary levels of storage, spillage has now increased to 35% of total wind and solar production.
Its use in hydrogen production is problematic because of huge variability in the amounts of energy and duration of its delivery.