1. U.S. Department of Energy, Energy Information Administration. Renewable energy 2000: issues and trends, Report DOE/EIA-0628(2000). Washington, DC: U.S. DOE EIA, Office of Coal, Nuclear, Electric and Alternate Fuels; 2001. See also: http://www.eia.doe.gov/cneaf/solar.renewables/rea_issues/rea_issues_sum.html.
2. U.S. Department of Energy, Energy Information Administration. Annual energy outlook 2005, with projections to 2025, DOE/EIA-0383. Washington, DC: U.S. DOE, EIA, Office of Integrated Analysis and Forecasting; 2005. See also: http://www.eia.doe.gov/oiaf/aeo/.
3. Public Utility Commission of Texas. Substantive rules, Chapter 25 – Applicable to electric service providers. Subchapter H, Electrical planning, 25.173 – Goal for renewable energy. Austin, TX; 2004. See also: http://www.puc.state.tx.us/rules/subrules/electric/.
4. U.S. Department of Energy, National Energy Technology Laboratory. Fuel cells show value for key industries, Policy Facts 08/2002. Pittsburgh, PA: U.S. DOE, Office of Fossil Energy, NETL, Strategic Center for Natural Gas; 2002. See also: http://www.netl.doe.gov/publications/factsheets/policy/Policy013.pdf.
5. Public Utility Commission of Texas. Substantive rules, Chapter 25 – Applicable to electric service providers, Subchapter H, Electrical planning, 25.172 – Goal for natural gas. Austin, TX; 1999. See also: http://www.puc.state.tx.us/rules/subrules/electric/.