Historically, during the creation of a unified energy system, base load power plants were constructed in Estonia (shale power plants) and Lithuania (the Ignalina nuclear power plant and the Elektrenai power plant). In Latvia, the Daugava hydropower plants were designed for peak, half-peak and emergency modes in which it is possible to relatively quickly and simply implement the sudden increase or decrease of capacity according to necessity. Neither coal nor shale power plants allow such sudden change of generation capacity due to a technologically more complex process. Latvian largest electricity supplier JSC "Latvenergo" 72% of the electricity - 3.6 TWh (2012) produced from renewable and environmentally friendly energy sources. JSC “Latvenergo” uses two types of energy resources in the energy generation process: renewable energy sources in hydropower plants and in biomass and wind power plants; highly efficient cogeneration in gas-fired power plants. Latvia already is one of the greener countries in the Europe in accordance with high level of energy production from RES and future strategies for energy sector development also include RES use for heat and electricity production. The Energy Strategy 2030 sets the following objectives of the energy policy: – Competitive economy – balanced, efficient, economically, socially, and ecologically justified energy policy based on market principles ensuring further development of the economy, its competitiveness in the region and world; – Sustainable energy – reduced dependency on imported energy resources, new and efficient technologies for the use of renewable resources are encouraged, measures to improve energy efficiency are implemented; Secure supply – stable energy supply and developed infrastructure provided to energy users.