ANRE, the energy regulator in Romania, has an interesting way of trading electric power. Its power exchange operates on Central European Time, whereas its over-the-counter platform operates on Eastern European Time. This is because the power exchange is part of the 4M market (the Czech Republic, Hungary, Romania, and Slovakia) which has standardized on CET, whereas the OTC platform is based on the local time in Romania.
As a result, a participant who trades a day ahead on the Romanian OTC platform can be caught out of balance if they attempt to clear their position on the exchange. ANRE says the cost of shifting their OTC platform to CET would exceed the benefits of simpler access to the markets. In the meantime, it would seem that there are interesting time-zone-based arbitrage opportunities in Romanian power trading (or maybe opportunities for anti-arbitrage? :-).
These are all 24-hour markets. Dumb question: why don't they standardize on UTC?
Udubasceanu S. Romanian regulator to maintain time-zone split across power trading platforms. ICIS 2015-10-15 <
http://www.icis.com/resources/news/2015/10/15/9933560/romanian-regulator-to-maintain-time-zone-split-across-power-trading-platforms/>