The bill should only be 2-tier if it’s politically impossible to have a clean RPS. If there’s a dirty tier (tier 2), the top tier must be truly clean and the dirty tier must not promote new facilities or create incentives for existing ones to stay open.
No smokestack technologies should be allowed. Emissions-free (clean) renewables only. Ideally, penalty fees should go only to solar photovoltaic, which is the technology in most need of support.