David Gelbaum

David Gelbaum ( 1950 - September 2018) was an American businessman and primarily green technology investor and environmental philanthropist.

Beginning in 2002, he invested up to $500 million in clean-tech companies through his Quercus Trust, with a portfolio of businesses involved in nearly every aspect of the emerging green economy, be it renewable energy, smart electric grids, sustainable agriculture, electric cars or biological remediation of oil spills. He was CEO and chairman of the Board of Entech Solar, a company he co-founded with Mark O'Neill.

Career Gelbaum was born and raised in Minneapolis, Minnesota, the second of four sons. His grandfather, Abraham, was a Ukrainian Jewish immigrant to the U.S. prior to World War I.

Philanthropy Gelbaum gave $200 million to the Sierra Club and $250 million to The Wildlands Conservancy, a land trust he co-founded that has acquired and preserved 1,200 square miles of land in California, including more than a half million acres of the Mojave Desert. He was responsible for the Sierra Club reversing its stance on immigration.

He signed The Giving Pledge in 2013.

It was revealed in a Bloomberg exposé that Gelbaum, along with two other partners of investment firm TGS Management, had quietly given over $13 billion to charitable causes over the previous two decades, using a web of trusts and private companies to hide their identities.