  There are many indicators of energy security. Few measure what really matters
-- affordable and reliable energy supply -- and the trade-offs between the two.
Reliability is physical, affordability is economic. Russia's latest invasion of
Ukraine highlights some of the problems with energy security, from long-term
contracts being broken to supposedly secure supplies being diverted to retired
power plants being recommissioned to spillovers to other markets. The
transition to carbon-free energy poses new challenges for energy security, from
a shift in dependence from some resources (coal, oil, gas) to others (rare
earths, wind, sunshine) to substantial redundancies in the energy capital stock
to undercapitalized energy companies, while regulatory uncertainty deters
investment. Renewables improve energy security in one dimension, but worsen it
in others, particularly long spells of little wind. Security problems with rare
earths and borrowed capital are less pronounced, as stock rather than flow.
