The problem with "Portugal powered solely by renewables last weekend" is it's not true

We sometimes see news articles proclaiming the virtues of wind and solar-generated electricity in a specific region. The example is chosen to highlight how good wind and solar are at providing electricity that is claimed to be "renewable" in some way. Not only does the idea of renewable ignore that it is an industrial process requiring immense mining projects and is very capital intensive, even the energy claims are usually false when examined in their full context.

Consider this article: Portugal powered solely by renewables last weekend from November 1, 2023. The article was short but included this text, and I have made a few words bold to highlight what is misleading:

Portugal relied solely on renewable energy last weekend, particularly wind and hydroelectric power, to meet electricity demand. It generated 172.5 GWh of renewable electricity and consumed 131.1 GWh between Friday night and Monday morning.

Wind contributed 97.6 GWh, hydroelectric 68.3 GWh, and photovoltaics 6.6 GWh, while exporting surplus power to Spain and taking advantage of favorable weather conditions.

 Start with "hydroelectric." This is a terrific source of power generation but is only available in a limited number of places in the world and most of the best opportunities for hydropower have been developed long ago. Yes, it is renewable, and yes it is a very clean source of electricity, but it is usually not waht the advocates for "renewable" energy mean - usually they refer to wind and solar and a smattering of tiny sources that they say hold promise. 

Next, consider that favorable weather conditions were present that weekend. Sunny days with steady wind. What about the roughly 2/3 of the day when the sunshine is so low no solar power is generated? Their data shows that some biomass, natural gas and other thermal power was generated, indicating that while wind, hydro and solar generated enough power to meet demand and even have some for export, they did not stand alone. And how much natural gas and other generating sources including import capability was available? Portugal would need 100% backup from reliable sources to cover the possibility that the wind does not blow and there is not much sunshine.

What about the days when the weather is not so favorable and what about the full-year picture? Portugal has terrific conditions for wind and solar but many places do not. With their good weather conditions, Portugal's energy data hub shows their annual consumption supply as in the graph below.

Notably, in 2022 wind provided 23.8%, solar 5.4%, biomass 6.4%, natural gas 33.1%, hydro 8.3% and 22.4% was imported. Ah, so now we see in the larger context that natural gas was their largest source of power by a wide margin, with wind only slightly leading imported electricity, and wind and solar combined were only 29.2%. 

Consider the export/import aspect of Portugal's electrical grid. With wind and solar they do not have control over how much power is generated since they can't control the weather, though there is some ability to predict short-term patterns. What happens when they have lots of wind and solar? Natural gas and hydro plants must be tuned down, and both of these are suitable for ramping up and down but of course, their large capital cost and capacity must be kept ready to go all the time, so much of their cost remains in the system. When Portugal needs additional power they often import it, meaning they depend on their neighbours having reliable power. But since weather is very similar for their neighbours, they can't all rely on wind and solar, some of them must have instantly dispatchable power not only to meet their own needs, but meet Portugal's shortfall too, meaning they have to be over-powered.

So, did Portugal rely solely on renewables that weekend? Not at all. They relied on:

1. Other power sources all of the time.
2. Other power sources when the sun did not shine.
3. Backup by reliable power sources in case wind and solar weakened or failed.
4. Reliable power generation in neighboring countries. 

Sure, the sum of their wind, solar and hydro was more than their total consumed but there is absolutely no way they could have actually provided reliable electricity even for that brief time without multiple alternatives and backups. And guess what, no other country and almost no region in the world can do so either. The next time you see an article trumpeting the victory of wind and solar electricity, consider the claims in their full context.