Whether it's a big established conglomerate or a fledgling start-up, everyone is cashing in to save the planet. Eco-friendly hybrid cars are slowly making their way to London's busy and crowded streets. But one former lawyer decided to take it to the next level, turning these cars into 'greentomatocars' - a taxi fleet made up of 40 hybrid cars. "The most striking advantage of running green tomato cars is that it has an environmental USP (unique selling point) which means that the demand for the service is very high. There are some increased capital costs in investing in a Prius as opposed to a conventional vehicle whihc might come in a few thousand pounds cheaper. And there are also long-term running costs, reductions in having the Prius which more or less balance themselves out after 3 or 4 years. But the advantage for our company is that we are able to make stronger and more consistent sales on the basis of our environmental offering," says founder Tom Pakenham who quit his desk job to go full-time with Greentomatocars. Pakenham is not the only one turning green in the transport sector. These bikes, called ENV - which stands for Emissions Neutral Vehicle - are powered by a fuel cell device which mixes compressed hydrogen with oxygen to create electricity that drives the bike. And the best thing about it, its manufacturers say, is that the only waste product is water vapour released from the vent. With a top speed of 50 miles an hour, a range of 100 miles on one tank of hydrogen, and a projected price of about $10,000 when it launches in the market in late 2008, makers say ENV is already attracting many potential buyers. "Well, there are a number of interested parties around the world who are operating fleets and are interested in being carbon neutral or running emissions-free. For example, rental fleets on tropical islands, courier fleets, delivery fleets and that kind of thing. There are also a number of hydrogen highway projects around the world where they are putting hydrogen infrastracture in but they can't find cost-effective vehicles to actually use the hydrogen," says Andy eggleston who is the project director for Intelligent Energy - the company behind ENV which is also developing fuel cell technology for cars and planes. But perhaps the biggest company that is bound to make a major impact is the world's biggest retailer Wal-Mart whose CEO recently reaffirmed the company's committment to saving the planet. "Whether it's the world's rapidly growing population or the worsening problem of global warming, we see the need for sustainable business practices as increasingly urgent. And perhaps more than anything else, we see sustainability as mainstream," said Lee Scott, Wal-Mart CEO, who recently spoke in a forum which included Britain's Prince Charles. Wal-Mart has already used its corporate muscle to persuade suppliers to reduce packaging by 5 percent over the next six years. Now, the company has teamed up with GE to develop low energy LED lights for refrigerator cabinets. "This will save us about 13 million U.S. dollars per year and reduce our carbon dioxide emissions by 63 million pounds - in weight. That's exciting," Scott said. On Wednesday, former U.S. Vice President Al Gore took his crusade against global warming to the Capitol Hill, and warned that the world faces a 'true planetary emergency.' Although so-called 'eco-entrepreneurs' and big businesses are looking at profit margins, they say the underlying reason remains the same: to save the planet. "If you are an individual, even a company who wants to make a step into the green world and you want to reduce your carbon footprint, if you want to project yourself as being greener, represent your business or your person as being greener, it's very difficult to do it. It certainly, generally involves spending money to do it. What we offer is a way of doing it for absolutely no extra cost," said Pakenham. But for some, the best thing about going green is simply having fun. "For me the key thing, the key difference compared to any other fuel cell two-wheeler today is that it's a huge amount of fun and if we try to sell this technology on the basis of its worthy, the chances are people are not gonna buy it. The key thing is they look great and they're a great fun to ride," said Nick Talbot, a director for Seymour Powell, an industrial design company.