Renewable Energy Sources (RES) are energy sources that are preserved in nature and can be completely or partially renewed, in  particular, hydropower, wind energy, non-accumulated solar energy, biofuel energy, biomass energy, biogas energy, geothermal energy, wave energy, tidal energy, landfill gas or sewage treatment plant gas energy.

One of European Union (EU) strategic objectives is to incentivize the use of RES as it is in accordance with the sustainable development strategy and it helps to accomplish the goals of the Kyoto Protocol regarding reduction of greenhouse gases emissions. On 27 September 2001, the EU adopted an important legislative document – Directive 2001/77/EC of the European Parliament and of the Council on the promotion of electricity produced from renewable energy sources in the internal electricity market.

The purpose of this Directive is:

• to improve security of supply by means of reducing dependence on imported fuels,
• evironmental protection,
• to enable regional development thereby increasing the employment by creating new jobs.

The Directive requires from Member States to accept the measures and incentives in order to reach the objective of 22.1% share of electricity produced from RES in the total EU gross electricity consumption by the year 2010.

The Ministry of Economy, Labour and Entrepreneurship, in the Regulation on a minimal share of incentivized electricity production from renewable energy sources and cogeneration, has set a goal to achieve 5.8% as the minimum share of electricity produced from RES in total consumption in Croatia by 31 December 2010. Since "green energy" includes the electricity generated by hydropower plants, about 50% of electricity generated in Croatia comes from RES.

However, since the share of other RES is minimal, the intention is to incentivize electricity production from RES through support mechanisms.