Even so, the demand for electricity was outstripping TVA's capacity to produce power from hydroelectric dams, and so TVA began to construct coal-fired plants. Political interference kept TVA from securing additional federal appropriations to do so, so it sought the authority to issue bonds. Several of TVA's coal-fired plants, including Johnsonville, Widows Creek, Shawnee, Kingston, Gallatin, and John Sevier, began operations in the 1950s. In 1955 coal surpassed hydroelectricity as TVA's top generating source. On August 6, 1959 President Dwight D. Eisenhower signed into law an amendment to the TVA act, making the agency self-financing.