In a previous question it has been shown the computation capabilities of the countries all over the world. However, if I didn't miss something, the use of such supercomputers is limited to researchers within the country. Is there any supercomputer that can be used for foreign researchers?
PRACE (Partnership for Advanced Computing in Europe)
PRACE is a European organization managing 7 main HPC centers in France, Germany, Italy, Spain, and Switzerland, and with 26 member countries that provide some additional resources.
Access is through the evaluation of research proposals via peer-review, and some calls specifically mention that they are "designed for projects requiring access to resources not currently available in the PI’s own country and whose projects do not require resources on the very largest (Tier-0) European Supercomputers or very large computational allocations".