In the absence of either such extreme scarcity payments or capacity payments, producers run up against the “missing money”-problem, which means that they are unable to finance their fixed costs. In practice, however, the capacity market option seems largely preferable to the VOLL option as it is far less uncertain and avoids the issue of barriers to entry - any market participant, for instance, would need to be able to play the whole merit curve, which implies a costly portfolio of means of generation - and thus persistent structural underinvestment with persistent price spikes. In the long run, the latter would create serious doubts about the viability of liberalised electricity markets.