In memory of cleantech investor David Anthony

No one ever really knows the inner struggles that lead to someone taking their own life — we only know when someone is gone and what they left behind. Longtime cleantech investor David Anthony has taken his own life, reports Fortune, and leaves behind a wife and young son, and a career of supporting early stage startups developing clean power and energy storage innovations.
Anthony led investments at a venture management firm called 21Ventures, which has provided seed, growth, and bridge capital to over 40 tech companies, mainly in the cleantech space. As Fortune’s Dan Primack explains it, 21Ventures didn’t raise a traditional venture fund, but would identify startup investments and bring them to high-net-worth individuals or family offices for investing.
Anthony worked closely with investor David Gelbaum’s Quercus Trust, which back in 2008 was the third-most active venture fund investing in cleantech according to the Cleantech Group. However Gelbaum seemed to have started to pull back on cleantech investments in late 2009, and told me in a rare interview in February 2010 that he had lost money in cleantech and hadn’t had any exits then (though back then he was still optimistic).
Anthony wrote a variety of columns for GigaOM over the years, and I’ve interviewed him several times about his investments starting back in 2009. The last time I heard from Anthony was last September 2011, when he was working with home solar startup OneRoof Energy, which just recently raised more funding.
Here’s the last three articles Anthony wrote for us and an interview I did with him:

It’s not a secret that cleantech has proven to be more difficult to invest in than many had anticipated. Particularly when investors compare it to the web ecosystem and exits like Monday morning’s $1 billion acquisition of Instagram by Facebook. Part of the problem with cleantech investing is the long timetables for a lot of the startup investments.
Regardless of whether 21Ventures’ cleantech portfolio has had successes or exits, I think it’s important to list out some of the investments, so we can look at the collective amount of innovation that was under development by 21Ventures led funds. Anthony was passionate about cleantech innovation, as well fighting climate change and supporting environmental causes.
Anthony received his MBA from The Tuck School of Business at Dartmouth College in 1989 and a BA in economics from George Washington University in 1982.
Some of 21Ventures supported startups:
AeroFarms: AeroFarms is a New York-based startup that develops tech-heavy urban farming processes. Anthony told me he thought that advanced farming techniques were an under-invested area where his firm sees promise. AeroFarms presented at the WSJ Eco:nomics conference recently and was voted the #1 company that investors would want to put $1 million in.
OneRoof Energy: OneRoof Energy develops and owns home solar rooftop installations and recently closed more funding.
Gravity Power: Gravity Power makes a gravity power module that uses a very large piston that is suspended in a deep, water-filled shaft and a return pipe connecting to a pump-turbine at ground level. As the piston drops, it forces water down the storage shaft, up the return pipe and through the turbine, and spins a motor/generator to produce electricity. To store energy, grid power drives the motor/generator in reverse, spinning the pump to force water down the return pipe and into the shaft, lifting the piston. The company just created a Germany-based subsidiary. (Bill Gates and Bill Gross recently invested in a gravity energy storage play).
Magenn Power: Magenn Power makes high-altitude wind turbines. I haven’t heard about this company in years.
ETV Motors: An Israeli lithium ion battery cell startup founded in 2008.
Graphene Energy: Graphene Energy is an Austin, Texas, based-startup that has been developing a technology using graphene, which can produce at least twice the storage capacity of commercially available ultracapacitors. Ultracapacitors have ultra-fast charge and discharge times, but lag far behind batteries in terms of the amount of energy they can store. Graphene Energy was an ARPA-E finalist, but I haven’t heard from these guys in awhile.
Axion Power International: Axion Power has developed a lead-acid/carbon energy storage tech that blends ultracapacitor technology with old-fashioned lead-acid batteries. The problem with ultracapacitors for electric vehicles has been low energy density; next to batteries, the amount of power ultracapacitors can store per kilogram doesn’t measure up. But they do excel in charge time and lifespan. Ultracapacitors can handle far more charge cycles than lithium-ion or lead-acid batteries, and they recharge quickly. The company is public on the OTC bulletin board and not profitable.
GreenRay Solar: GreenRay makes a solar microinverter, which places an inverter on each panel, instead of the more traditional central inverter set up. The market for microinverters is growing, and Enphase Energy recently went public.