Sustainable and efficient energy use can translate to significant savings for local taxpayers. But long-term savings from new technologies often require upfront investments that can be prohibitive even in less-trying economic times.

A program to retrofit Boston's streetlights demonstrates ways to overcome this challenge. As of last year, about two-thirds of the city's 64,000 electric streetlights used mercury vapor (MV) fixtures and one-third employed high pressure sodium (HPS) fixtures, which are about 25 percent more efficient. The streetlights use about $7 million worth of energy per year.

In 2009, Boston began planning to use light-emitting diode (LED) technology for some of its streetlights. LED is even more efficient than HPS, and the fixtures last three and a half times longer than MV fixtures. The following year, NSTAR, a local utility, approached the city about replacing its MV fixtures with HPS. When the city proposed going straight to LED, NSTAR hesitated, citing uncertainty about widespread adoption of the technology and high costs, which the utility pegged at $600 each for fixtures with an estimated life expectancy of 50,000 hours.

Working with local good-government organizations, Boston set about making a financial case for LED. Between technological improvements and casting the net to more potential manufacturers, the city was able to cut the per-fixture price in half, to $300, and extend life expectancy to 70,000 hours.

The new numbers added up for NSTAR, and 17,600 LED fixtures should be installed by the end of this year. While the fixtures themselves are largely being paid for by a state-mandated energy efficiency program, Boston is paying to install them.

To ensure best value on installation, the city set up a competition between its employees and a private company. After city workers proved to be the most cost-effective option, the workers were able to achieve additional efficiencies and signed a contract with Boston that further reduces installation costs.

With fewer than 4,000 of the conversions completed, operating savings already have reached $400,000 a year. Annual savings should reach $2 million once the current phase of 19,000 conversions is complete, and the city plans to convert all 64,000 streetlights to LED over the next eight to ten years.

Besides long-term operating-cost savings, there are environmental benefits for the city. The electricity consumed by streetlights is responsible for 17 percent of Boston's greenhouse-gas emissions. LED technology will cut emissions from electricity generation to power the streetlights in half, reducing the release of greenhouse gases by 7 million tons annually.

The up-front costs of converting to energy-efficient technologies can be daunting. But Boston's experience with streetlights shows that by taking advantage of both government and private-sector efficiency incentive programs, and by maximizing competition to reduce costs, transition challenges can be overcome despite tight public budgets.