Portugal's energy system operator had some interesting news to share once March had closed out. It seems that even as Portugal's monthly energy consumption increased 9.7 percent compared to March 2017, the country produced enough renewable energy (just over 4,800Gwh) to exceed its energy demand (just over 4,600Gwh).

This doesn't mean Portugal avoided fossil fuel use; these figures just compare the total gigawatts of renewable energy produced with the total gigawatts of energy demanded for the whole month. Sometimes, that demand didn't coincide with the time that the renewables were producing, so natural gas and coal plants had to be used. Still, according to the Portuguese Renewable Energy Association (APREN), the day with the least amount of renewable consumption (March 7) still had enough to meet 86 percent of Portugal's demand through renewable energy. On the other extreme, Portugal's renewable energy sector produced 143 percent of its demand on March 11. In fact, Portugal's electricity consumption was met fully by renewable energy for a 70-hour period beginning on March 9 and for a 69-hour period beginning on March 12.

Extra energy can be exported or used to pump water for Portugal's pumped storage , APREN President of the Board António Sá da Costa told Ars via email. The Association confirmed that no water in the pumped storage facilities was turbined in March, so that water can be used to create more renewable energy in June or July, when hydroelectric power might run low.

March is generally a good time for Northern Hemisphere renewables to set records: winds are robust, mountain snow melt and/or heavy rains create strong hydroelectric conditions, more and more sunlight becomes available, and electricity demand is usually low with milder temperatures because people aren't running their heaters or air conditioners. Though more fossil fuels are usually needed to meet summer and winter demand in most places, "shoulder season" records aren't meaningless—they're proof that high-penetration renewable scenarios are possible.

APREN noted this, too: "These data, besides indicating a historical milestone in the Portuguese electricity sector, demonstrate the technical viability, security, and reliability of the operation of the Electrical System, with a large share of renewable electricity."

Portugal got lucky this month with a good amount of rain after a drought, which allowed for a lot of hydroelectric production. It also saw better-than-average wind conditions in March. APREN reports that 55 percent of electric consumption in Portugal came from hydro in March, and 42 percent of consumption was met by wind. In total, the renewable energy that Portugal consumed in March avoided the emission of 1.8 million tons of CO 2 .

According to the Portuguese transmission operator (abbreviated as REN), these conditions have been consistent throughout the first quarter of 2018. Out of all the energy produced by the country between January and March, 42.1 percent came from hydro and 35.1 percent came from wind. Natural gas accounted for 10.7 percent of production, coal for 6.2 percent, biogas for 4.4 percent, and solar for one percent.

Consumption showed a slightly different story, considering that dispatchable resources from fossil fuels and biogas are used to meet demand when variable resources like wind can not. (Portugal imports energy and exports some of its energy, too, so we're getting an imperfect picture when looking at a country in a silo.) In total, 31 percent of consumption was met with wind, 24 percent with hydroelectric, 5 percent with biogas and 1.1 percent with photovoltaics. Among fossil fuels, 22 percent of the country's consumption was met with natural gas and 17 percent with coal.