I know that Norway has subsea power cables to various European countries. Apparently the North Sea Link[1] which came online in 2021, is the longest such cable in the world at 750 km.

Drawing a 750 km line from the coast of Morocco I can almost reach Barcelona, Spain. With perhaps some advances, and including the distance of the branching network, I think reaching "enough" of European power consumption is doable.

[1] https://en.wikipedia.org/wiki/North_Sea_Link

edit: actually, looking at terrestrial interconnectors the record is much farther already, 2210 km between Hami and Zhengzhou in China.[2]

Coincidentally, Wikipedia mentions that the longest proposed cable is in fact the Xlinks Morocco-UK Power Project[3], which the Washington Post article failed to mention. At 3,800 km, the power losses would apparently amount to 13%.

[2] https://en.wikipedia.org/wiki/Interconnector [3] https://en.wikipedia.org/wiki/Xlinks_Morocco-UK_Power_Projec...