Robert Congel, a commercial real-estate developer who lives in upstate New York, has a plan to 'change the world.' Convinced that it will 'produce more benefit for humanity than any one thing that private enterprise has ever done,' he is raising $20 billion to make it happen. That's 12 times the yearly budget of the United Nations and more than 25 times Congel's own net worth. What Congel has in mind is an outsize and extremely unusual mega-mall. Destiny U.S.A., the retail-and-entertainment complex he is building in upstate New York, aspires to be not only the biggest man-made structure on the planet but also the most environmentally friendly. Equal parts Disney World, Las Vegas, Bell Laboratories and Mall of America-- with a splash of Walden Pond m the 'retail city' will include the usual shops and restaurants as well as an extensive research facility for testing advanced technologies and a 200-acre recreational biosphere complete with spring-like temperatures and an artificial river for kayaking. After a false start in 2002, countless changes of plan and a storm of local opposition, Congel is finally breaking ground again, with a projected completion date of 2009. Later this month, bulldozers powered by biodiesel are scheduled to begin leveling the site, a rehabilitated brownfield in Syracuse, Congel's hometown. Whether Congel's firm, the Pyramid Companies, can maintain the cash flow and political support needed to complete the project is a subject of much local debate. Also disputed are Congel's goals of creating 200,000 jobs regionally and making Destiny nothing less than 'the No. 1 tourist destination in America.' More mind-boggling than the sheer scope of Destiny is its agenda. Congel emphasizes that renewable energy alone will power the mall, with its 1,000 shops and restaurants, 80,000 hotel rooms, 40,000-seat arena and Broadway-style. theaters. As a result, Congel says, Destiny will jump-start renewable-energy markets nationwide with its investments in solar, wind fuel cells and other alternative-energy sources. But if Congel does manage to erect his El Dorado, will it really help cure our country's addiction to scarce and highly polluting fossil fuel? Or will it just be a cleverly marketed boondoggle that may create more environmental problems than it solves? All by itself, the mall would boost America's solar-electric power capacity by nearly 10 percent. 'On every level, this project astounds,' Senator Hillary Clinton said in April, claiming that the mall could make the area a hub for clean technologies and deliver a shot of adrenaline to upstate New York's ailing economy. To help foot the bill for Congel's project, Clinton and other politicians successfully persuaded Congress to provide financial incentives for mega, scale green development projects. (Destiny, of course, will face little competition to reap those benefits.) The mall is astounding because______