It's difficult to keep up with everything in the cleantech space right now. Probably a good thing. Here are some items to note:

• Renewable Ventures got sold to MuniMae. It's a bit surprising, given that RV (mostly involved in solar project finance) had just finished arranging a $100mm pool of capital back in February. Does this signify the potential beginnings of a period of fund acquisition in the cleantech space, as other investors look for ways to get a jump start on getting into the market? RV continues to recruit and hire, by all reports, so they're clearly still planning to be very active.

• GridPoint announced a $16mm Series B, led by the Altira Group, and also including Contango Capital Management and Advantage Capital Partners, adding onto a large number of angel investors. We've discussed the company's home energy storage/ management appliance in the past, when they raised $9mm back in November.

• BusinessWeek's Deal Flow blog has the scoop on another Vinod Khosla ethanol investment: Mascoma. Apparently a $4mm round. More info on the company's licensed technology here.
  

• Since about a dozen folks have forwarded around bits and pieces of the NYT special section on green business today, here's a handy link.

Other interesting tidbits: Sorry, Bob, "Enertech" is already taken. But Bob Metcalfe's post is well worth checking out for his perspective on the possibility of an "energy bubble"... Here's an interesting interview with a silly title... More evidence of large acquisitive players being active in the cleantech market... Here's a link to the pdf of E2's report on cleantech clusters (just for you, Matt Marshall)... Lastly, a solar IPO you may not have heard of...

Some assorted items of interest from the past week or so:

John Doerr really, really, really likes cleantech/"greentech." And so do I (self-promotion alert -- I particularly enjoyed the highlighting of Tiger Optics, one of Expansion Capital's portfolio companies, check them out). And so does Mark Huang of GE Commercial Finance (update: another self-promotion alert, mentions Agile Systems, another one of Expansion Capital's portfolio companies, check them out too). All joking aside, all three aforementioned columns do a great job of highlighting some of the current debates and discussions going on in the cleantech VC community:

• How do you define "cleantech" in the first place? The latest PWC Moneytree survey data for Q1, for example, seems to have cleantech deals scattered across a lot of different categories (batteries under "Electronics/ Instrumentation", energy efficiency technologies under "Telecommunications", and of course a hodgepodge under "Industrial/Energy", etc.). Not picking on PWC Moneytree, it's actually a good illustration of the simple fact that "cleantech" remains in the eye of the beholder, as we've discussed here before.

• What kinds of investment periods should be expected in cleantech? Is the impact of regulations and policies greater in this investment area than in others?
  

• Is the solar space getting too crowded? Whether it is or isn't, what's next?

Toward that last question, there has been a lot of talk in the cleantech investment community over the past few days about the very successful IPO of Basin Water (up to $17 at time of writing). Does this mean VCs will now get serious about water tech? Also: The results from the Ignite Clean Energy contest were announced -- no surprise, three solar startup winners out of five total prizes. Guess Dan Primack was right after all. (Red Herring profiled top prize winner Stellaris for those interested -- more info here, too).

Meanwhile, in other news:

• Another biofuels project got financed -- Galveston Bay Biodiesel, in a Series B by Contango Capital Management and Chevron Technology Ventures;
  

• Here's a good review of some of the potential of energy efficiency technology;
  

• And lastly, here's a sobering picture.

Here are a couple of fun items of note:

• Using viruses to build the battery of the future? That's what some researchers at MIT appear to have been working on. Besides the intriguing virus angle, the article also serves to illustrate how much effort is being put into figuring out how to make batteries store more energy per weight. Lots of creative thinking in energy storage out there right now, and lots of investors interested...

• ...And what more fun way to apply energy storage technology than in a souped-up electric-powered race car like the WrightSpeed. 170mpg (equivalent), but be honest, is that really why you want to take a test drive? I've seen the car in person (no test drive, alas), and it does look like fun...

Enjoy!

• SolarCentury, a UK-based developer of rooftop solar systems combining both thermal and PV, completed a ~$10.3mm round of financing. VantagePoint Venture Partners led the round, which also included existing investors Scottish and Southern Energy. A conversion of $2.6mm of debt into equity was part of the round. The company reports they doubled revenues over the past year to nearly $30mm.

• CleanEdge and NASDAQ have announced they are teaming up on a clean energy index. Yet more visibility for investments in the cleantech segment, even if it's not directly related to private equity investments. Joel Makower shares some of his thoughts on the announcement on his personal site today...

• Israel Cleantech Ventures announced they are raising a $60mm fund to target primarily early-stage Israel-based cleantech investments. One of the principals of the firm, Jack Levy, was kind enough to write a few words on the Israeli cleantech scene on this site back in January. And speaking of Israeli cleantech investing, BASF also appears to be looking at ramping up their venture activities in the region as well...

• UPC Wind, a wind farm developer, announced they received funding from the D.E. Shaw Group and Madison Dearborn. The amount of the financing was not disclosed.
  

• Here's an interesting article on solar concentrators from News.com. And speaking of solar, following up on the earlier speculation about Applied Materials possibly moving into the solar business, here's some big-dollar confirmation...
  

Several energy efficiency-related deals over the last couple of days, including a couple of broadband-over-powerline (BPL) plays:

• Current Communications announced a new $130mm third round of financing. New strategic investors include TXU, GE, EarthLink, and Sensus Metering Systems. Existing investors EnerTech (majority owner), Google, Goldman Sachs, Hearst, Duke Energy, and Liberty Associated Partners also participated. TXU is busy rolling out BPL using Current's systems, and EarthLink is the retail internet partner. Current last raised $100mm in their second round of financing less than a year ago. Clearly a lot of big players are making major bets on BPL becoming a "third pipe" into the home -- and as an enabler of two-way communications for metering and energy-using devices, BPL (and its simpler cousin "powerline carrier" or PLC) can help "demand response" and other cleantech applications gain more market traction.

• Another BPL-related company, Broadband Energy Networks (BEN), which is connecting to BPL networks with energy management applications, announced they have raised $2.5mm of an anticipated $3.9mm Series A (the RH article is pretty confusing on the numbers, however, so this total could be wrong). 21Ventures provided $1mm in funding, CEO and Founder Lawrence Silverman provided $1.5mm, with $1.4mm still open in the round.
  

• Blue Ridge Numerics, which provides software to help engineers optimize product design for efficiency, took in an undisclosed amount of funding from Global Environment Fund (GEF).

• Energy management software/ solutions provider Prenova announced an inside round, which appears to have been less than $2mm (based upon the company's 2003 $15.5mm round and details in this press release -- note, opens a pdf). Existing investors include Frontenac, River Cities Capital Fund, and Austin Ventures.
  

Busy last couple of days:

• Innovalight, which is developing silicon ink-based solar PV technology, announced a $7.5mm Series B, led by Harris & Harris. Existing investors Apax Partners, ARCH Venture Partners, Sevin Rosen Funds and Triton Ventures also participated in the round.

• Iogen, which is developing technology to produce cellulosic ethanol from agricultural waste, took in $30mm in financing from Goldman Sachs. The company had previously raised significant capital ($20mm from the Canadian government, $100mm in "internal funding and funding from strategic partners" from Petro-Canada and Royal Dutch/Shell). Some indication of valuation is given by the fact that Goldman's stake is a minority ownership. Iogen is planning on breaking ground on a commercial plant based upon their technology sometime next year, with production beginning in 2009. The Red Herring article linked to above also has a nice description of the funding challenges facing capital-intensive new technologies like Iogen's...

• Ovation Products, which is developing a "clean water appliance" for distributed wastewater treatment, took in an undisclosed amount of funding from Andlinger & Co.