The study carried out in five European countries by the International Project for Sustainable Energy Paths (IPSES) demonstrated that by using a Least Cost Strategy it is possible to save about US$60,000-80,000 million per year (real base-year 1990) by the year 2020 in comparison to the business as usual projection made in a study by the EEC/EU. This least cost strategy would lead to approximately a 40% decline in primary energy demands and carbon dioxide (CO2) emissions by the year 2020.
In a study by Greenpeace ("Towards a Fossil Free Energy Future"), the Stockholm Institute investigated a strategy to phase out fossil fuels by the year 2100 and to phase out nuclear power by the year 2010. This was possible by a step by step reduction of CO2 emissions with 10% by the year 2000 (in comparison with the year 1988), 26% in 2010, 68% in 2030 and finally 100% in 2100. The Institute has judged the strategy to be feasible and potentially economically beneficial.
Twelve US states have enacted renewable electricity standards.