Current developments in generation portfolios and market design urge the need to attract additional balancing services in the form of frequency restoration reserves (FRR). This work elaborates on the opportunities and constraints of current balancing markets in the Netherlands and Germany to harness the profitability and feasibility of energy storage systems to participate in load-frequency control and in FRR in particular. One of the main concerns of storage is the state of charge, i.e. availability of discharging or charging energy respectively. Even though firm capacity needs to be provided, the Dutch market allows bids to be withdrawn up to one hour ahead of operation. Therefore Energy Storage System participation in the frequency restoration process encounters limited risk compared to the case of the German system. Furthermore, the Dutch system allows passive balancing, where Energy Storage Systems can contribute in an opportunistic fashion without the need for firm contracts.