Nancy Floyd was early to the greentech investing game. A prominent venture capitalist, she founded and remains the managing director of Nth Power, an early-stage venture capital fund based in San Francisco. Nth Power, a $180 million fund, has seen a number of successful exits, including companies specialized in biofuels and "smart" meters.

More than a quarter century ago, Floyd founded NFC Energy, one of the country's first wind development companies. She has also been active in non-profit energy projects, such as home audits, and sat on the Vermont Public Uitlities Commision. These days, she makes bets on the future of greentech. I sat down to talk with her in San Francisco. Here's an edited transcript of our conversation:

When Serious Materials announced $60 million in additional venture capital funding last month, investor Jim Pettit felt more than a little bit vindicated. Pettit and his venture capital firm Navitas Capital led the early funding rounds in Serious, a Sunnyvale, Calif. maker of energy efficient building materials such as windows and drywall material. Along with his partner Travis Putnam, Pettit had positioned Navitas to be an early player in a greentech sector -- construction and building materials -- that had lots of promise but huge barriers to entry.

The latest injection represents the largest funding round for greentech energy efficiency in 2009, according to the Cleantech Group. And it is likely an early indicator of a big bump in venture activity in this space. Venture capitalists, burned out on expensive and capital-intensive energy generation players focused on biofuels and solar panels, are looking to the more mundane areas of energy conservation and efficiency as places to lay their markers.

For the past year, silver linings have been in short supply. Even as financial markets claw their way back up, the wealth lost has been neither forgotten nor completely recovered. In the private equity sector, the good news is that, frankly, the situation could have been worse. Though returns plunged, the asset class still outperformed the public equity markets.

A new analysis from alternative investment research firm Preqin puts the private equity industry's return at -30 percent for the 12 months ending March 31, 2009, a period that encompasses the bulk of the lows without the benefit of the upswing that followed. For the same year-long period, the S&P 500's return was -38.1 percent, with the MSCI Europe's at -49.9 percent and the MSCI Emerging Markets' return at -47.1 percent.

Cleatech is back in vogue, and financiers are jumping to get back into the green game. The latest quarterly cleantech funding numbers, released Tuesday by consultancies the Cleantech Group and Deloitte, show that preliminary results for the third quarter -- tallying clean technology venture investments in North America, Europe, China and India -- totaled $1.59 billion going to 134 companies. That's a 10 percent increase over the second quarter.

The improvement was fueled by a wave of big venture capital financings, and the successful IPO of battery company A123 Systems (AONE) helped the cleantech sector continue to rebound in the most recent quarter. The U.S. stimulus package also helped VCs make up their minds when placing big bets.

Steve Jurvetson is the youthful partner at famed venture capital firm Draper Fisher Jurvetson. He is among the most respected VCs in Silicon Valley, with a string of successful investments under his belt, including Hotmail (acquired by Microsoft, MSFT) and Interwoven (IPO, then acquired by Autonomy), among others. He has made billions of dollars for investors and is reputed to be among the smartest VCs in the world. He got his electrical engineering degree from Stanford in a mere 2.5 years, graduating No. 1 in his class.

He designed communications chips for HP, worked in marketing for Apple (AAPL) and NeXT, and served at the elite consulting group Bain & Company. Like many VC peers, he jumped from IT into greentech. Jurvetson currently sits on the boards of several hot cleantech startups, including Tesla Motors and Synthetic Genomics, which is why I recently buttonholed him at a conference for a Q&A. Jurvetson suggested I join him for lunch. I didn't realize lunch meant sitting in on an impromptu pitch session from a fledgling company, providing a fascinating, first-hand view of how the mind of one of the world's greatest VCs works in real time.

Vinod Khosla is considered the leading cleantech investor in the world today but many of his peers still wish he would shut up. A founder of computer company Sun Microsystems (JAVA) and former general partner at venture capital powerhouse Kleiner Perkins Caufield & Byers, Vinod Khosla piled into the green investment space more than five years ago and was an early believer.

He has since become a vocal cheerleader for the sector. On September 1, he announced that he had raised a whopping $1 billion for investments in a new venture capital fund, Khosla Ventures, to be focused on green technologies. Prominent backers including CalPers, the powerful and enormous public workers pension fund for California. But along the way Khosla has quietly alienated many in the venture capital green investment community with his brash public statements at big conferences. "What is he bashing this week?" quipped one green technology consultant when Khosla's name came up in conversation at the recently concluded AlwaysOn Going Green Conference in Sausalito, California.

The biofuels market is in a funk. Corn-based ethanol has become an environmental pariah to activists and an economic lodestone to people in favor of energy independence. Plant-based biofuel companies seeking to harvest oils from green matter have struggled to reach economies of scale and have faced political headwinds in Europe. And biofuels based on rendering animal and food waste have run into rough waters.

Alone among the biofuels remains algae, a prolific reproducer that is the current great hope among venture capitalists and other investors.

TechCrunch reports that Twitter is about to sign a contract to take an investment of $50 million that would value the company at $1 billion. On a per-user basis, that valuation would make Twitter worth 1.5 times more than Facebook. And that would be a nice payday for the earlier Twitter investors.

It's particularly attractive for a company that, unlike Facebook, currently has no revenues. Yet it is amazing how much Twitter has penetrated the national psyche since February when I interviewed co-founder Biz Stone. Back then, Twitter had a total of $55 million in venture capital and claimed that it had grown at 900 percent since early 2008.

Why does Tesla Motors, the ambitious Silicon Valley electric car company, need a $465 million taxpayer loan if it can raise hundreds of millions of dollars from private interests? Its latest round was a cool $82.5 million from a private investor group led by Fjord Capital Management.

"It was an opportunistic investment," Elon Musk, the former Paypal honcho and CEO of Silicon Valley-based Tesla told Bloomberg on Tuesday at the Frankfurt Motor Show.

"We were not looking for money," Musk said. Indeed. The Department of Energy just approved a $465 million taxpayer loan to Tesla as part of the federal government's green tech stimulus. The loan will apparently be doled out to Tesla on an "as needed" basis. But why?

Someone stole all the tea at the TechCrunch50 Conference. All the tea bags, that is. I wanted a pick-me-up and coffee can send me over the top. Alas, no tea. "I'm so sorry. This is the first time in all my years of catering that this has ever happened," said one of the catering company reps. (She's lucky the event's co-founder Mike Arrington wasn't around to experience the moment). But the tea heist incident seemed, in a nutshell, to summarize the mood at the annual confab that lets startups pitch their technology. Everyone wanted something. VCs didn't want too pay much. CEOs didn't want to get paid too little. No one wanted to leave empty-handed.

The turnout was solid, with a packed hall and sharp-elbowed blue-shirted bizdev guys battling it out for the best seats in the house. Startup execs were hesitant about money and worried that they might not be able to raise what they needed. The judges were more supportive than in years past (when contestant iMo had a snafu in demoing its mobile iPhone driving game app, judge Yossi Vardi led the audience in an encouraging cheer).

Here's some advice to entrepreneurs looking for early stage capital to build a mobile phone or mobile Web application. Hit up your grandma, cash out your IRA, or look under the car seat for quarters. Because you certainly aren't going to get any love from the venture capitalist community. In data released on Thursday at the Gigaom Mobilize 09 Conference, Thomson Reuters revealed that so-called "A" round investments in mobile startups has fallen off the map.

On an annualized basis, "A" round of financings for mobile companies fell 91 percent, from $405 million in the first nine months of 2009 to $37 million at the same point in 2008, a truly staggering decline. And it's not as if 2008 was a stellar year for venture capitalists, either, as the U.S. economy began imploding and limited partners began to default on capital calls in droves.

Kai-fu Lee has $115 million, and he wants to put it to work. Monday, he announced that his new angel-focused venture fund, Innovation Works, is targeting a rate of five successful Chinese start-ups a year. Previously, Lee was in charge of Google's (GOOG) operations in China.

The new endeavor is backed by several high-profile investors – including YouTube co-founder Steve Chen, electronics manufacturer Foxconn (FXCNY) and Legend Holdings (LGDI), Lenovo's parent company.

If conventional wisdom mattered, super venture capitalist Vinod Khosla could not have picked a worse time to launch a massive venture capital fund focused on extremely risky green technology investments. Yet Khosla, a VC legend in Silicon Valley, not only pulled it off but ended up money away, according to the New York Times.

In fact, many of Khosla's investors are gun-shy state pension funds, still smarting from nasty losses suffered in venture capital and private equity placements that went horribly wrong in the economic meltdown of the past two years.

Larger transactions and increased investor confidence pushed clean technology ("cleantech") venture capital investments higher in the second quarter of 2009. Investments in companies dealing with energy efficiency and solar power led the overall market, which surged 73 percent quarter-over-quarter. A study by Ernst & Young, with data from Dow Jones VentureSource, suggests a sharp up-tick in cleantech venture capital.

Venture capital investment in cleantech companies hit $572 million last quarter. Forty-eight financing rounds were completed, representing a 100 percent increase in quarter-over-quarter transaction count. Compared to the second quarter of 2008, which was the second best cleantech quarter for venture capital investment, capital put to work fell 59 percent, with the number of transactions down 16 percent.

Two years after it grabbed the public's attention by securing $7 million in venture capital financing, Zivity, a social networking company that focuses on art nude photography, has voluntarily parted ways with much of its staff and capital. And, in a rarity when large amounts of cash are involved, everybody's walking away happy.

The reason for the split, according to Cyan Banister, Editor-in-Chief of Zivity and one of its founders, was that the site "clearly won't be a venture win on a short time scale." She maintains her confidence in the endeavor and believes that Zivity will be profitable soon, but continues, "It's going to grow organically, at its own pace." Meanwhile, competing projects within the company – notably the TopFans website and "War of the Roses" MySpace application – were beginning to receive more attention internally.