Alex Liftman, global environmental executive for Bank of America, addressed the criticism by saying the financial services industry is not the only sector that bears responsibility for reducing the economy's dependence on coal.

"The issue of coal is a global one issue, not a bank issue. … For this transition to take place, all of society needs to make this a priority," Liftman said.

"There is an expectation that the financial sector play a key role in ensuring that global markets account for environmental and social risks and impacts," said Mindy Lubber, president and CEO of sustainable business advocacy group Ceres, in an email.  "Bank of America's leadership program is moving in exactly the right direction by showing that what is good for the planet is also good for business."

The $50 billion that Bank of America plans to spend by 2023 on coal alternatives is mind-boggling. There are four primary focuses:

• Energy efficiency projects for residential, commercial and public properties
• Renewable energy projects including wind, solar, hydro, biomass and waste-to-energy solutions
• Alternative transportation technologies including electric and hybrid electric vehicles and the components and charging infrastructure to run them
• Innovative technologies for water purification and waste management

Bank of America says that it chooses these projects using the same rigorous criteria for returns that it expects out of any investment.

"These are all solid business deals," Liftman said. "This isn't philanthropy."

As of March 31, 2012, Bank of America had committed $17.9 billion to projects of this nature. Some examples include:

• $8.4 billion for energy efficiency, including $55 million dedicated to loans and grants for retrofits in low-income neighborhoods
• $5 billion on renewable energy projects. In 2011, the company arranged the financing for the world's two largest rooftop solar projects (including the SolarStrong military housing project, which almost collapsed when the federal government backed out)
• Close to $1 billion for consumer financing related to hybrid vehicle purchases

Aside from the $50 billion investment commitment, Bank of America is also planning $100 million in grants and investments for non-profits and community projects. For example, it is working with the U.S. Green Building Council to help ensure that LEED certifications can be earned on low-income housing, Liftman said.

The bank also announced several new green operations goals, including a 25 percent reduction in energy consumption by 2015 (compared with a 2004 baseline); a 20 percent cut in paper usage and water consumption (compared with its use in 2010); and a 70 percent diversion of global waste from landfill.

Next page: Investments across financial industry