Make It Modular: Why Wind & Solar Are So Resilient
Even as the tragic blackouts in Texas were unfolding, defenders of dirty fossil fuels were desperately pointing their fingers at wind power, the Green New Deal, and anyone or anything else they could come up with to deflect blame. In truth, wind and solar power were not the primary cause of the grid failure in Texas — the main culprit was fossil gas plants that went offline. In fact, wind and solar are intrinsically more reliable than fossil power, but not in the way that you might think.
Wind and solar’s intrinsic reliability advantage comes from their modularity. A 250MW wind farm is typically made up of more than 100 individual wind turbines. If one of those turbines has a mechanical problem, the wind farm loses less than 1 percent of its potential output. And the odds of that happening to more than one turbine at a time are small.
On the other hand, a 250MW fossil gas combined cycle turbine plant — the most common type of large gas plant — is typically made up of two combustion turbines feeding a steam turbine. A mechanical failure of one of the combustion turbines cuts the plant’s production capacity by half. If the steam turbine or the gas supply fails, which happened during the February storm, the whole plant goes down.
A solar farm has a similar modularity to a wind farm. A 250MW farm is made up of thousands of individual solar panels and generally few to no moving parts. (Some solar plants are designed to track the sun.) The loss of an individual solar panel would be virtually unnoticeable. Solar panels are usually connected in 10MW chunks to inverters. Even if one of these goes down, the farm would lose only 4 percent of its generating capacity. Conversely, coal and nuclear power plants generally rely on a single boiler to make steam that typically goes through multiple turbines. If those boilers break down or the system feeding coal into the plant breaks down, the plant loses its entire capacity.
As my colleague Rachel Fakhry writes, wind and solar have much lower “forced outages,” which is what they call it when power plants breakdown. In 2017 in biggest power market in the country, gas plants and coal plants have forced outage rates of between 2.5 percent and 12.5 percent. Meanwhile, wind never gets above 2 percent and solar is close to zero. That’s the modularity at work.
The modularity of individual wind and solar projects is mirrored at the system level. The average wind farm built in the last decade is 108MW. The average solar project is 37MW. Compare that to combined-cycle gas plants (average size 700MW), coal (700MW) and nuclear (1,670MW). If a single wind or solar project goes offline, the system loses a much more manageable chunk of power.
If we combine this modularity with a more robust and interconnected grid, we can take advantage of geographic diversity: in almost all cases, the wind is blowing and the sun is shining somewhere. If we further take advantage of improvements in weather forecasting, wind and solar become an extremely reliable source of power.
Cold weather and ice storms don’t automatically stop wind farms. There are wind turbines that operate regularly in the Arctic and other cold weather places like Sweden because they are designed for cold weather conditions. Similarly, there are fossil gas plants in Canada and nuclear power plants in the north of Russia that operate through much colder weather than Texas experienced because they are designed to do so.
Ultimately, the system failures that led to the blackouts and deaths in Texas were primarily caused by a failure to design the system for these conditions. The Texas grid has limited connections to the rest of the country not because of some inherent feature of grid technology, but because of a misplaced desire to avoid federal regulation. As my colleague Ralph Cavanaugh explains, California also faced extreme weather (albeit in the form of high rather than low temperatures) but only had to cut about 1/40th of the power that Texas did and for a fraction of the time because California’s grid is robustly connected to the rest of the states in the West.
If we want a system that is resilient in the face of increasingly erratic weather driven by climate change, we need to plan for it and build for it. If we don’t, we will continue to face similar disasters. Properly planning for these weather events means choosing renewables not only because they help stop making climate change-related weather events worse, but also because their modularity gives them a built-in reliability advantage over fossil resources.
Robustly connecting an increasingly renewable generation mix and some storage to an increasingly efficiency and flexible demand side and we’re on a path to a clean, affordable, reliable and resilient grid. It’s not as easy as pointing fingers, but it will actually make the world a better place for all of us.
Originally published on NRDC blog.