Oil breached $90 per barrel Friday, setting another world record in a week full of top oil prices.

The spike -- driven by concerns about possible supply disruptions as tensions rise between Turkey and Iraq -- could turn out to be another milestone for greentech.

Greentech entrepreneurs certainly benefited when oil prices breached $55 per barrel in 2005 (see Oil Prices Grease Cleantech, Oil Spike's Tech Impact) and when they hit another record of $73 per barrel last year (see Record Oil Prices Help Hybrids).

Companies and investors say high oil prices have played a significant role in raising interest in green technologies, even though many of these technologies -- solar, for instance -- have replaced conventional electricity, not oil. (Very little electricity is made from oil nowadays, with oil mostly being used to make fuel.)

Sure, there are some indirect connections. Oil prices do impact natural-gas prices, and natural gas is used to make electricity.

But regardless of whether alternative-energy technologies compete directly with oil, high oil prices do attract shareholders.

Oil prices "have this huge affect on the market perception," said Travis Bradford, president of the Prometheus Institute, a Greentech Media Research partner. "It has a much greater effect [on greentech] as a signal or attention-getter than direct economics."

While institutional investors are probably savvier about realizing the connection between oil prices and greentech is indirect -- and that electricity prices have a more direct relationship to technologies such as solar power -- retail investors still seem to associate the two, he said.

"Retail investors drive much of the volatility," he said. "Expectations create valuations."

On Friday, though, the WilderHill Clean Energy Index, which monitors clean-energy stocks in the United States, fell 3.8 percent to 245.77 points in spite of oil prices that hit $90.07 per barrel before sinking to $88.60 per barrel.

It could be evidence that investors are beginning to disassociate greentech stocks with oil prices, as Mark Cox, CEO of the New Energy Fund hedge fund, suggested last month (see Greentech Finds Independence from OPEC).

That might be good for the industry if prices ever fall.

But one day's results aren't enough to make that call. Recession fears brought valuations down overall Friday, with the Dow Jones industrial average falling 367 points.

And, looking at the year to date, the WilderHill index is up 33.1 percent from Jan. 3, compared with about 9.4 percent for the S&P 500.

"I don't think there's a disconnect at all," Bradford said. "Investors are behind this trend, but they are getting more savvy, and not just investing in every stock."

Lower share prices for greentech companies could be due to concern about the overall economy and uncertainty about regulations coming from Congress, he said.

After all, oil prices do impact the whole economy, he said.

"Higher oil prices put the whole economy in danger because it crowds out spending on other things, not the least of which are consumer goods," he said. "The risk of creating inflation could bleed through into the price of money. So while [high oil prices] might be helping cleantech, directly or indirectly, on one side, it actually is putting the larger economy at risk."

In the meantime, the industry will be watching for oil to hit its next milestone -- the inflation-adjusted record of nearly $101.70 per barrel set in 1980.