How do you know the green finance sector has arrived? Well, it got its first Ponzi scheme! Allegedly.

The SEC filed charges against four people and two companies in a Denver federal court on Monday. Mantria Corp. and its principals, Troy Wragg and Amanada Knorr, stand accused of running raising $122 million from more than 300 investors in what could be a dozen fraudulent offers of securities. Mantria engaged Speed of Wealth LLC, run by Wayde and Donna McKelvy, to dump the cash out of their retirement plans and tap their home equity to "invest" in Mantria, which they said was offering returns ranging from 17% to "hundreds of percent" every year.

Investors hoping to ride the climate change bandwagon have had a roller coaster ride over the past two years. Greentech stocks soared with the oil spike in 2007 and 2008, then crashed with stock market and commodity price declines in 2009. Since then, some of the most obvious stock plays have strongly rebounded. Many solar stocks have posted high double-digit gains since rebounding off year-to-date lows in March 2009.

The leading solar panel manufacturer, FirstSolar (NASDAQ: FSLR) has appreciated by 45% from lows of near $100 to a closing price of $154 on October 14. "I wouldn't be stepping into buying these stocks right now," says Pacific Crest senior analyst Mark Bachman, who covers solar stocks. Still, he rates FirstSolar as a market perform and considers it the best solar stock at present on his coverage list.

Across the country, college classes are starting. In each of these classrooms, students are struggling with calculus, trudging through Candide, and wondering just what the hell they're going to do with their degrees upon graduation. The last of these is characteristic of every college student, especially those of us, with the foresight fortitude recklessness zeal to major in liberal arts fields (in my case, Philosophy).

The anxiety is a bit higher this year, given a high rate of unemployment, the likelihood of a "jobless recovery" and the fact that it could take years for destroyed value to be recovered.

We're still in the early stages of this trend, but it's pretty clear that the green energy sector is fast becoming a venture capital darling. Today, for example, five deals were announced in one publication alone (three VC, two acquisitions). The three investments account for $47.4 million in VC investment. And only yesterday, Solazyme picked up another $57 million in its Series C round.

In what remains a capital-constrained market, the cash is still flowing. In the private equity space, investments in clean technologies have remained steady from 2007 to 2008, despite broader economic calamity. Such commitment this early in the game may hint at what the next bubble will be.

It was going so great for a while. Investors were eagerly pouring cash into renewable energy stocks as solar and wind energy seemed the perfect answer to the looming energy crisis. The more the news became grim and gas prices went up, the more investors fled to companies like First Solar (NASDAQ: FSLR), driving the stock to over $300 a share in the spring and summer of 2008. Today, the stock closed at $115.75 and has hovered in the low 100s for past few weeks.

This climate has changed, all right: it's changed to "fear." No longer are investors content to contribute to long research & development cycles for unproven business models; nor are they satisfied that credit will be available to finance the major capital expenses which accompany wind and solar energy systems. The world may be sinking ever faster into an energy crisis, but it's the financial one that matters far more to opportunistic investors -- and with a recent drop in demand, industry watchers are concerned prices may not hold up to mid-2008 expectations. According to green fund manager Chris Walsh, quoted in a Reuters article, "There are too many players out there, and there are too many smaller players."

In my opinion, while the best-performing alternative energy stocks were certainly pricey in early summer, the downturn they've taken is shortsighted. The recent plunge in oil prices (and let's remember it's a plunge only compared to the newly-set benchmark of 2008) won't last for more than a few years, at most, if worldwide oil production models are correct; and then alternative energy sources will gain renewed interest from investors; making it a likely long-term bet.

A world without ice cream is unthinkable. But serving up frozen food in the U.S. in the middle of the summer (when we scream most loudly for ice cream) is creating greenhouse gases due to the hydroflourocarbons used in most refrigerators and freezers. Something must be done.

Enter Ben & Jerry's, whose parent, Unilever (NYSE: UL) has been working with Greenpeace, McDonald's (NYSE: MCD) and Pepsico, Inc. (NYSE: PEP) to develop more global-warming-friendly (or unfriendly?) freezers. The company will be rolling out the country's first HFC-free freezer in convenience stores and supermarkets across the U.S.; and as a bonus to your favorite ice cream outpost, the green freezers use about 10% less energy than their HFC-emitting cousins.

The new freezers use butane rather than HFC as a refrigerant and required special permission from the EPA; which has banned the use of butane and propane (which are used throughout Europe and Central and South America for refrigerators and freezers) because these hydrocarbons are flammable and are blamed for depleting the ozone layer. The 2,000 freestanding Ben & Jerry's freezers are just a test, and it may be eight to 10 years before the company is allowed to replace all of its 100,000 freezers nationwide.

While it will likely be an extremely moderate impact on expense reduction, the rollout of green freezers stands to underscore Ben & Jerry's ethical, do-gooder image in the mind of its consumers and give it yet another edge over rival Haagen-Dazs.

Minyanville's Sean Udall dares to share the kind of keen insight and actionable information you won't find in any prospectus. Here he answers a reader's burning question about "green" stocks. For more original thought, visit www.minyanville.com.

Professor Udall,

Do you have any opinions on Zoltek Companies, Inc. (NASDAQ: ZOLT)? My wife wants me to buy everything "green". Her last "green" company idea was General Electric (NYSE: GE). I know, right? I bought a little just to quiet the noise level. I'm into a little SunPower (NASDAQ: SPWR) and Evergreen Solar (NASDAQ: ESLR). Does Zoltek have legs?

Thanks,

Minyan L.

Minyan L.,

First, that's hysterical. Second, a word of caution: Going all green, or all of any one thing, is something I'd never advocate. If you do, you do so at your own risk, as nothing in the market is ever as obvious as it seems, especially when it seems totally obvious.

If the nation's oil companies are having trouble getting more crude out of existing fields, perhaps the solution is to put rigs in Yellowstone National Park.

"Green" environmentalists may be in for bad days. According to The Wall Street Journal, "Increasing U.S. oil production would require overturning decades-old moratoriums that limit offshore drilling and accelerating leasing of federal lands." It may come down to whether eagles and black bears mind oil exploration in the regions where they live.

Forest animals may not care, and that could be the crux of the argument. Although oil spills are not unheard of, they have become exceedingly rare. Bringing out oil from protected land may have very little environmental risk.

In some ways, opening restricted land may be the only way to save lower class and some middle class Americans from gas and oil prices so high that their spending ability is being crushed.

What black bear would want to see that happen?

Douglas A. McIntyre is an editor at 247wallst.com.

Whole Foods Market (NASDAQ: WFMI) is banning plastic bags from its 270 locations. The switch to a choice between reusable bags and paper will take effect on Earth Day, April 22.

It's certainly a bold move and demonstrates a lot of concern for the environment. It will also spruce up Whole Foods' image as an environmentally-conscious retailer and generate a ton of free publicity for the company, starting with the New York Times story.

Whole Foods has served as a trend-setter for the larger grocery chains, and this move could inspire stores like Kroger (NYSE: KR) and Safeway (NYSE: SWY) to make similar switches, depending on how it works out.

During its trial runs, Whole Foods found that eliminating plastic only led to a 10% increase in paper bag use, demonstrating that consumers tend to switch to the reusable bags.

That's good for the environment, and it also cuts costs: Even Wal-Mart (NYSE: WMT) has taken notice by phasing in reusable bags as a third option. The plastic bag seems destined for obsolescence.

The 21st century may be the end of the "Plastics, young man!" era.

Google (NASDAQ: GOOG) is a leader when it comes to being a "green" kind of company. It shuttles employees from the Bay Area to its Mountain View headquarters in biodiesel vans, has what is considered the be the largest solar array in corporate America and uses alternative energy in its operations, unlike most of the business world.

But what about all the actual electricity the company consumes? It has huge data centers all over the world that power its search and web product network, and these campuses consume gobs of electricity off the global grid. So, does Google purchase electricity for these data centers from electric cooperatives that generate all that juice with standard coal-fired electricity generation plants? Hard to tell, because the company won't say.

Wal-Mart (NYSE: WMT) has been making headlines for months with its environmental initiatives, and now Target (NYSE: TGT) is in the news. The retailer announced that it will be reducing the use of PVC in packaging and children's products.

The EPA classifies PVC as a human carcinogen. Target has been the subject of protests from environmental groups pressuring the company to reduce its use of PVC and be more environmentally conscious. Of course, Target says its plans to reduce its use of the product predate the protests.

Target's corporate website has a page devoted to its environmental initiatives. A few of the highlights:

• "Energy-efficient fluorescent lamps are used throughout our stores, a first in the retail industry. We are currently changing our sales floor lighting from a three-lamp to a two-lamp fixture, which will reduce our energy consumption by 22 percent."
• "Four stores in California draw 20 percent of their annual electricity needs from their own rooftop solar-panel systems. In 2007, Target will retrofit 14 more California stores to operate on solar power."
• In 2006, the company "reused 385 million garment hangers and recycled 2.1 million pounds of plastic and 153,000 pounds of metal from broken hangers."

Wal-Mart and Target appear to be locked in a battle to one-up each other on environmental responsibility, and that's great news for the planet.

Japanese automaker Toyota (NYSE: TM) stole the hybrid vehicle marketing limelight years ago with its Prius passenger car -- you know, the one that has a gas mileage figure of over 50 miles per gallon. Due to combining a smaller gasoline engine with an electric motor, the smaller car has a remarkable fuel efficiency rating, and the word of mouth that started selling the Prius to ecologically-aware consumers and assorted environmentally-conscious folks was like a wildfire in the passenger car market. The waiting line to buy one was half a year in many cases.

Although many detractors say the Prius' claimed gas mileage is not what it's cracked up to be, the popularity contest has already been won. The next step for Toyota would be to make the nameplate in an all-electric fashion instead of a hybrid design that still uses gasoline. The trouble is, no company can produce an all-electric car that has the same amenities as the modern internal combustion vehicle: range, comfort, size, price and design. If anyone can ever make this a reality, though, it would be Toyota (although an effort is still plenty of years off).

Until then, perhaps the automaker is looking at plug-in electric hybrid vehicles for Act II of its hybrid car marketing strategy? At the recent Tokyo Auto Show, Toyota showed off designs that use a hybrid propulsion system that contains a larger battery, allowing the vehicle to travel short distances at highway speeds powered by the electric motor alone, instead of the motor just being used in city stop-and-go traffic. The battery pack would need recharging at night, instead of being charged by regenerative braking like in current designs, but all things considered, this would be the next step to an all-electric design that uses little to no internal combustion (or gas). Whoever gets there first will hold the holy grail of sales to customers needing smaller passenger cars. General Motors (NYSE: GM) isn't sitting still at all, though.

TheStreet.com's Jim Cramer explains why the unique dynamic of oil as a commodity gives alternative fuels a "magic" price point.

Boy, that ethanol is cheap. It's cheap if we use corn, and it is even cheaper if we use soy. It doesn't matter how much it costs or how much infrastructure is needed, it's become the low-cost gasoline even with the stupid unnecessary subsidies.

Amazing, isn't it? But that's why Monsanto (NYSE: MON) (Cramer's Take) and Bunge (NYSE: BG) (Cramer's Take) are so cheap and why all of the various "sun" stocks are inexpensive. Oil at $92, going to who knows where, is going to make all of these unnaturally natural alternatives the low-cost fuels.

There are a lot of fuels that are cheaper to produce than oil now, particularly if you read Chris Edmond's unbelievably good series out of the Middle East. It's all demand-on-fire, supply disappearing that is controlling the price. It isn't Nigerian terrorism or Iranian intransigence or Iraqi-Turk tensions.

Those are all just headline terms by writers searching for a reason to write about oil jumping. They have no choice. They can't keep writing "because supply is outstripped by demand," even though that's what is happening.

In a sense, we have a fabulous opportunity as a country to make some headway here on domestic security because of this umbrella. Even coal, which will now never amount to much given the Democrats' desire to stop global warming, becomes too viable to ignore as the rallies in Peabody Energy (NYSE: BTU) (Cramer's Take) and Arch Coal (NYSE: ACI) (Cramer's Take) show.

So, the endless moves up will continue. I have never seen a commodity that has no price at which demand tapers. So anything with a price point of $80 or less is now a go.

Including all crops that will burn.

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RELATED LINKS:

The Five Dumbest Things on Wall Street This Week

The 'Hannah Montana' Stock Index

Jim Cramer is a director and co-founder of TheStreet.com. He contributes daily market commentary for TheStreet.com's sites and serves as an adviser to the company's CEO. At the time of publication, Cramer had no positions in stocks mentioned.

Wal-Mart Stores (NYSE: WMT) has announced that the head of its environment program is leaving his position for another one involving the management of Wal-Mart's private-label merchandise. In the wake of Harriet Hentges' resignation that was effective at the end of last week, one has to wonder what is going on inside the retailer's environmental interfacing group.

Hentges was in charge of "stakeholder engagement," which included labor relations, environmental sustainability and acting as a liaison with external groups. Now, Andrew Ruben is vacating his position as the head of environmental relations between the world's largest retailer and groups like Environmental Defense and the Natural Resources Defense Council.

Ruben was considered to be the public face of Wal-Mart's environmental sustainability campaign, which from an outsider's perspective has seen great PR strides in the last year. Wal-Mart has announced greener, more efficient trucking fleets, packaging-waste reduction agreements with vendors, and energy-use curbing in stores, all under Ruben's watch.

Add to that setting up a visit by former presidential candidate Al Gore to come talk global warming with Wal-Mart execs, and Ruben's had plenty of watchers inside the company. Why is he leaving for something completely unrelated, then? Well, he'll oversee the development of more sustainable private-label products for Wal-Mart, so he's not leaving the environmental field completely within the retailer.

Ruben will be replaced by Matthew Kissler, who was responsible for packaging-reduction efforts at Sam's Club, Wal-Mart's consumer wholesale division.

TechCrunch reports that Greenpeace is chiding Apple Inc. (NASDAQ: AAPL) for the iPhone's toxic chemical ingredients. Moreover, Greenpeace's analysis suggests that the iPhone is losing "green ground" to other mobile phone competitors which are in the process of eliminating the iPhone's toxic chemicals.

According to Greenpeace, the iPhone contains toxic brominated compounds (indicating the presence of brominated flame retardants (BFRs)) and hazardous PVCs. Two of the "phthalate plasticisers" found at high levels in the iPhone headphone cable are classified in Europe as 'toxic to reproduction, category 2′ and are banned from use in all toys or childcare articles sold in Europe.

Greenpeace's analysis of competitors is most interesting: Nokia Corp. (NYSE: NOK) is totally PVC free while Motorola Inc. (NYSE: MOT) and Sony Ericsson already have products on the market with BFR free components. I am in Greenpeace's camp on this one. I also think that if Apple cleaned up the iPhone, it would find that green means green -- particularly in Europe.

That's something that Apple shareholders and Greenpeace would both celebrate.

Peter Cohan is president of Peter S. Cohan & Associates. He also teaches management at Babson College and edits The Cohan Letter. He has no financial interest in the securities mentioned.