MSD CAPITAL, L.P. bought NONE

Footnotes

Represents a purchase of securities from the issuer in the form of a capital call. Under the terms of a subscription agreement between the reporting persons and the issuer, the reporting persons are required to fund drawdowns to purchase shares of the issuer's common stock up to the amount of their capital commitment on an as-needed basis with a minimum ten business days' prior notice to the reporting persons.; Includes shares acquired pursuant to the reinvestment of dividends under the issuer's dividend reinvestment plan.; Noble Environmental Investments, LLC ("Noble Investments") is the record holder of these shares of the issuer's common stock. MSD Portfolio L.P. - Investments ("MSD Portfolio") indirectly owns Noble Investments through wholly-owned subsidiaries of MSD Portfolio, and MSD Portfolio may be deemed to beneficially own securities owned by Noble Investments. MSD Capital, L.P. ("MSD Capital") is the general partner of MSD Portfolio and may be deemed to beneficially own securities owned by MSD Portfolio. MSD Capital Management LLC ("MSD Capital Management") is the general partner of MSD Capital and may be deemed to beneficially own securities owned by MSD Capital. [Cont.].; [Cont.] Michael S. Dell is the owner of MSD Portfolio and the controlling member of MSD Capital Management and may be deemed to beneficially own securities owned by MSD Portfolio and MSD Capital Management, respectively. Mr. Dell disclaims beneficial ownership of such securities except to the extent of any pecuniary interest therein.; Each of Noble Investments, MSD Portfolio, MSD Capital, MSD Capital Management and Mr. Dell declares that neither the filing of this statement nor anything herein shall be construed as an admission that such person is, for the purposes of Section 13(d) or 13(g) of the Securities Exchange Act of 1934, as amended, or any other purpose, a member of a group with respect to the issuer or securities of the issuer.