bulbs which lasted only two years with 56-watt LEDs that would last a decade, and expected to reduce its public lighting energy use by half. However, for the first two years, DTE Energy continued to bill Ann Arbor at the same rate as before, because the street lights were not metered, and electricity charges were estimated based on past use. Under the direction of the state utility regulator, DTE Energy eventually revised its rates for Ann Arbor based on the expected energy use for "experimental lighting technology", and credited the city retroactive to the installation. As of January 2011, the city of Ann Arbor had switched 1,400 of its 7,000 streetlight fixtures to LEDs, and saved approximately $200,000, including reduced maintenance costs. Other electric light generation methods Towers Many cities across the United States experimented with tall tower structures to deliver light to entire city neighborhoods, similar to the arc lamp installation at the Wabash County Courthouse in Indiana. In 1802, Benjamin Henfry erected an oil-based "thermolamp" on a tall column in Richmond, Virginia, which failed to cast as much light as he had hoped for. In Washington, DC, city planners considered using the Washington Monument as a tower platform for lighting, but rejected the idea after placing test lamps on the Smithsonian Institution and United States Capitol buildings. Municipalities that adopted tower lighting or "moontowers" for a period included Akron, Aurora, Austin, Buffalo, Chattanooga, Denver, Detroit, Elgin, Evansville, Fort Wayne, Hannibal, Kansas City, Los Angeles, Louisville, Minneapolis, Mobile, San Francisco, and San Jose. Most of these cities erected only one or two towers, before falling back on traditional lamppost lighting. One exception was Los Angeles, which erected 36 towers, fifteen of which were 150-feet tall and equipped with three 3,000-candlepower arc lamps each. Another exception was Detroit, which attempted to use 122 towers to illuminate 21 square miles of the city. Although the tower lighting in Detroit provided "uniform carpets of light", it was ineffective in providing sufficient lighting for high-traffic areas and routes. After five years, Detroit began to dismantle its towers. As of October 2021, the only lighting towers that remain in the United States are in Austin, Texas. The city of Austin purchased 31 of Detroit's used moonlight towers in 1894. Seventeen of those towers, erected in Austin in 1895, continue to function as working lighting towers today. Induction lighting In 2009, PSE&G in New Jersey