Per BBC, the only power plant in Gaza has shut down, due both to fuel shortages and the lack of parts needed to make repairs. Israel's blockade continues to prevent the flow of food, medicines and fuel from reaching the 1.5 million residents of Gaza. In addition, banks are running out of cash, leading them to limit withdrawals. From AP
[M]ost banks have sharply curtailed withdrawals over the past two weeks and some have posted signs telling customers they cannot take out any more money. The U.N. stopped distributing cash handouts to Gaza's poorest last week.Economists and bank officials are warning that tens of thousands of civil servants will not be able to cash paychecks next month."No society can operate without money, but that's the situation we are reaching in Gaza," said economist Omar Shaban.
While Israel ostensibly is blocking currency from reaching Gaza to limit Hamas' ability to fund attacks, the article further notes that Hamas does not use the banking system, but smuggles funds through tunnels between Gaza and Egypt.
Oh, and collective punishment is still a violation of the fourth Geneva Convention.