Goldman Sachs bought pieces of two carbon-offset companies.

• E+Co, a company focused on bringing clean power to developing countries, announced that Goldman had purchased a majority of its carbon-offsets portfolio.
• Goldman took a minority stake in BlueSource, which is more focused on the tiny offsets market in the United States, and plans to market BlueSource offsets to clients.

Goldman  invested in APX, a California company that registers carbon offsets.

Goldman made early investments in other companies that stand to gain from cap and trade legislation.

• Wind power by investing in  Horizon Wind Energy.
• Renewable diesel with Changing World Technologies
• Solar power by partnering with BP Solar exactly the kind of deals that will prosper if the government forces energy producers to use cleaner energy.

More recently Goldman purchased a 10% stake in the Chicago Climate Exchange, where coincidentally carbon credits will be traded.

Other demonstrations of investment banks’ interest in the offsets field include, Credit Suisse invested 44 million euros in EcoSecurities, an Ireland-based offsets firm.

JP Morgan bought ClimateCare, another offsets group.

Morgan Stanley took a 38 percent stake in MGM International, yet another such firm.

Banks buying into the offsets business could benefit if a federal carbon-trading system is introduced in the United States.