Mandatory renewable energy targets are part of government legislated schemes which require electricity retailers to source specific proportions of total electricity sales from renewable energy sources according to a fixed time frame. The purpose of these schemes is to promote renewable energy and reduce dependency on fossil fuels. If this results in an additional cost of electricity, the additional cost is distributed across most customers by increases in other tariffs. The cost of this measure is therefore not funded by government budgets, except for costs of establishing and monitoring the scheme and any audit and enforcement actions. As the cost of renewable energy has become cheaper than other sources, meeting and exceeding a renewable energy target will also reduce the cost of electricity to consumers.
At least 67 countries have renewable energy policy targets of some type. In Europe, 28 European Union members states and 8 Energy Community Contracting Parties have legally binding renewable energy targets. The EU baseline target is 20% by 2020, while the United States also has a national RET of 20%. Similarly, Canada has 9 provincial RETs but no national target. Targets are typically for shares of electricity production, but some are defined as by primary energy supply, installed capacity, or otherwise. While some targets are based on 2010-2012 data, many are now for 2020, which ties in with the IPCC suggested greenhouse gas emission cuts of 25 to 40% by Annex I countries by 2020, although some are for 2025.
Renewable energy technologies are essential contributors to the energy supply portfolio, as they contribute to world energy security, reduce dependency on fossil fuels, and provide opportunities for mitigating greenhouse gases. The International Energy Agency has defined three generations of renewable energy technologies, reaching back over 100 years: