The Blackout Explained in Six Graphs

The energy shock experienced by most of Spain last Monday has exposed the seams of an electrical system with some deficiencies that experts had been warning about for months. Even today, the exact cause of the blackout that began at 12:30 p.m. on Monday remains unknown, but it is believed that the intermittency of renewable energies and the lack of investment to renew the grid are the causes of a structural weakness in the system that favours such incidents.

In his first press conference after the blackout, President Pedro Sánchez stated that the cause of the power supply failure on the Peninsula was that a total of "15 GW were suddenly lost, in just five seconds." These 15 gigawatts (GW) are approximately equivalent to 60% of Spain's total electricity demand at that time on Monday morning.

According to data from Red Eléctrica, the total electricity demand on that Monday morning, April 28, was 25.2 GW. Of the total supply, more than 70% came from renewable energies. Solar (photovoltaic source) was the largest percentage of energy generated at that time with 54.86% of the total. This means that solar energy provided more than half of the light illuminating mainland Spain at that critical hour because the system chooses the cheapest source and Monday was a very sunny day in most of the country.

Wind energy was far behind with 10.87% of the total supply that morning, and nuclear with 10.52%. Meanwhile, hydroelectric power accounted for 9.86% and combined cycle (plants that burn gas to produce electricity) for 3.8%. In other words, at the time of the collapse, renewable energies (wind, hydroelectric, photovoltaic, thermal, combined cycle, cogeneration and waste, turbination and pumping) generated 26,203 MW compared to 5,954 from non-renewables.

After the blackout, the price of electricity has skyrocketed. The cause of this increase is not specifically the blackout, but this Wednesday the average cost of electricity in the wholesale market soared by 450% to 31.83 euros per megawatt hour (MWh), according to data collected by the Iberian Electricity Market Operator (OMIE).

Despite this spectacular increase, the average price has been below 50 euros/MWh for eight days. It has been a very volatile April, with prices rising on some days to 65 euros/MWh and on others being almost zero. Even so, Wednesday's price is 28% lower than a week ago, but it is 950% higher than the 3 euros/MWh a month ago, on March 30, reflecting the great volatility of the market in recent weeks. In year-on-year comparison, Wednesday's figure is 40.4% cheaper than a year ago: on April 30 last year, the price was 53.44 euros per MWh.

The blackout, which has had an economic impact estimated by the Government at around 400 million euros, is now focused on its origin. Minister Sara Aagesen is now urging the electricity companies to provide data on the blackout. The Vice President also insisted against the most widespread thesis among experts about the origin of the 'national zero', stating that the participation of renewables in the mix was no different on Monday than on other days.