  Each day the world inches closer to a climate catastrophe and a
sustainability revolution. To avoid the former and achieve the latter we must
transform our use of energy. Surprisingly, today's growing problem is that
there is too much wind and solar power generation at the wrong times and in the
wrong places.
  We argue for the construction of TerraWatt: a geographically-distributed,
large-scale, zero-carbon compute infrastructure using renewable energy and
older hardware. Delivering zero-carbon compute for general cloud workloads is
challenging due to spatiotemporal power variability. We describe the systems
challenges in using intermittent renewable power at scale to fuel such an
older, decentralized compute infrastructure.
