Unfortunately, this is unlikely to be an effective use of resources (speaking as someone who worked in high-performance computing for the past 18 years). The resources you can contribute will be dwarfed by the volume and efficiency of cloud services and supercomputers. Even then, due to network constraints the only possible tasks will be embarrassingly parallel computations that do not stress network or memory, and very few scientific computing tasks have this form.
Unfortunately, this is unlikely to be an effective use of resources (speaking as someone who worked in high-performance computing for the past 18 years). The resources you can contribute will be dwarfed by the volume and efficiency of cloud services and supercomputers. Even then, due to network constraints the only possible tasks will be embarrassingly parallel computations that do not stress network or memory, and very few scientific computing tasks have this form.