Paragraph. In the event that any technological innovation allows for new forms of renewable energy not provided for in the regulations, the CNE may, on an ad-hoc basis, apply as evaluation period, within the current regulations, the period that it considers most appropriate for the regulation of the new energy source. ARTICLE 21.- All the authorities of the electricity subsector will ensure that 25% of the service needs for the year 2025 are supplied from renewable energy sources. By the year 2015, at least 10% of the energy purchased by distribution and trading companies will come from renewable energy sources. SPECIAL REGIME FOR BIOFUELS