At large scale, what issues arise with Renewables?
Today wind contributes roughly one percent and solar about one one-hundredth of a percent of all U.S. electricity generated. Proponents of renewables argue that large amounts of variable and intermittent power can be easily accommodated in the present power system. Opponents argue that even levels as low as 10% of generation by variable and intermittent power can cause serious disruptions to power system operations.
A much-expanded role for variable and intermittent renewables is technically possible. But, only if we adopt a systems approach that considers and anticipates the many changes in power system design and operation that will be required to make this possible There is a considerable risk that if we do not do the necessary planning, and develop the necessary new policy environment, serious problems could develop resulting in a major backlash against renewables in a decade or two. The U.S cannot afford to let that happen.
As an example, it is well known that the wind blows more strongly at night, while in most systems demand for electricity is strongest in the afternoon and early evening. It is possible that wind farms located off-shore may produce power that is better matched to demand due to the on-shore afternoon breezes, but at present there are insufficient data for the U.S. to say this with certainty. We have access to a new data set that may shed light on this issue. Wind also calms in the summer, at the same time that the demand for air conditioning is large. One of our PhD students is now looking at the question of whether wind, like water, may have years of very low production (wind droughts). Wind farms in both the Pacific Northwest and in Texas recently experiences extended periods during which the wind did not blow. Solar power has similar variability due to clouds, and of course is intermittent because there is no sun at night. Our detailed research has found that the fluctuations at time scales shorter than a few hours are worse for solar power than they are for wind.