The Ocean Renewable Energy Coalition (OREC) has prepared an overview of tax benefits for the MHK industry here.  As the spreadsheet shows, MHK receives more benefits than it did five years ago, but at the same time, it lacks parity with other renewables:  MHK projects do not qualify for 5 year MACRS, and are only eligible for half of the PTC available to other renewables.  OREC continues to work to achieve parity.