Most likely it'd be burned in a bioenergy powerstation.
Drax in the UK [1] is a quite good case study for this (assuming they get it all up and running), though they're not using algae. Right now they grow trees, and burn those in pellet form. It's currently considered sustainable as it's not adding new carbon to the above-ground system (whereas coal/gas/oil is adding to the above-ground carbon). Their next phase is to attempt to capture the post-combustion emissions from their chimney stacks, at which point they have a non-biodegradable mass of carbon to bury somewhere.
Even in that baroque interpretation of sustainability it's surely unsustainable once you include the emissions produced by harvesting, packaging and transporting the fuel.
It's less sustainable than renewables, but fills a practical requirement for peaker style powerplants (which fill sudden demand) without resorting to coal/oil/gas, which are considerably less sustainable. Drax already existed as a coal/gas facility, so transitioning it to a biomass-with-carbon-capture facility is a net benefit to the environment, even when considering the packaging and transportation of the wood, because those steps were required for its coal predecessor.
Drax in the UK [1] is a quite good case study for this (assuming they get it all up and running), though they're not using algae. Right now they grow trees, and burn those in pellet form. It's currently considered sustainable as it's not adding new carbon to the above-ground system (whereas coal/gas/oil is adding to the above-ground carbon). Their next phase is to attempt to capture the post-combustion emissions from their chimney stacks, at which point they have a non-biodegradable mass of carbon to bury somewhere.
[1] https://www.drax.com/sustainability/sustainable-bioenergy/