That is very expensive. Given that they came online in the 70s and early 80s we can assume the initial capital investment is paid off by now and that cost is only the marginal running cost. (OPEX)
Now, currently we are building solar farms in desert areas for ~1.5 cent per kWh. Including both CAPEX and OPEX. On-shore wind is built at ~3 cents per kWh and ~6 cents per kWh for off-shore.
This is where the explosion of renewables is coming from, they currently undercut the marginal cost of traditional power sources.