While the economy in general has been slow, the cleantech industry has kept IPOs interesting. As of August 20, five companies in the green sector had filed the paperwork necessary to have an IPO this quarter, according to an Investors interview with Matthew Molberger, a market tracker of Renaissance Capital.

Five filings in approximately seven weeks isn't enough to call this the quarter of cleantech, but there's still time for more filings. It's a clear improvement over the first half of 2008 already: over the first six months of this year, only four cleantech companies filed paperwork for an IPO and only two have actually gone public. Molberger said, "To make a (trend), we need to see another string of flings in the coming weeks. But I think we're certainly starting to see a foundation."

The five companies that have filed so far this quarter are quite varied: One works with rechargeable batteries (A123 Systems). Another is in wind-power (First Wind Holdings). Two more are in solar power (STR Holdings and GCL Silicon Technology Holdings). The last is reusing food waste as fuel (Changing World Technologies). Despite the differences between these companies, though, they share certain opportunities. These sorts of cleantech companies have become very popular with investors, with interest growing along with oil prices. Although oil prices have dropped from the high of $147 per barrel earlier this summer, they are still high enough to guarantee investor interest in any company successfully working on clean power. There's also a quiet expectation that the new president — no matter which candidate wins in November — will enact legislation that provides incentives for alternative energy companies. Both Barack Obama and John McCain have discussed the need for such incentives during their campaigns.

Compared to the same time last year, IPO filings are down 43 percent. Only 138 companies have filed in this period and, while five cleantech companies might seem like a small count, cleantech IPOs represent the only rising number. Of course not all cleantech companies are perfect investments, but they're at least able to get an investor to pay attention.

It seems very likely that a few more cleantech companies will file for an IPO before the end of the year. And if those IPOs do come through, they will cement the cleantech industry's spot as the strongest investment around. Even when the economy recovers, cleantech will remain a solid investment.

Photo — Kwong Yee Cheng