One of the biggest complaints against hydraulic fracturing or "fracking" -- the process of injecting high-pressure fluids to release hydrocarbons trapped in deep shale reservoirs -- is that it harms the environment.

Even as fracking has helped bring about a veritable shale revolution that has sent U.S. oil production to a multi-decade high and helped reduce the nation's dependence on foreign energy, it has also drawn the ire of those concerned about the environment.

Environmental groups and climate change campaigners have been highly vocal in their contempt for the process, which, they argue, has polluted water supplies with toxic chemicals that pose serious threats to the welfare of humans and wildlife. That's why, with so much on the line, companies are racing to develop environmentally friendly fracking fluids.

Source: Carrizo Oil & Gas.

Fracking's toxic cocktail
Environmentalists' claims certainly have some merit. According to a 2011 report by Democrats within the House Energy & Commerce Committee, energy companies operating within 13 states injected 780 million gallons of fracking fluids into wells between 2005 and 2009. Of the 2,500 different products found in these fracking fluids, more than 650 contained chemicals that are characterized as either known carcinogens or hazardous air pollutants, the report found.

For instance, the most commonly occurring chemical in these products was methanol, a hazardous air pollutant that was found in nearly 350 different products. And at least one of the highly toxic group of B.T.E.X. chemicals, which includes benzene, toluene, xylene, and ethylbenzene, was also found in injected fluids over the five-year period.

While there are plenty of other studies out there suggesting that these chemicals, when used in small quantities, pose a negligible threat to water supplies, many remain unconvinced. That's why developing a fracking fluid that can be convincingly shown to be harmless to the environment could herald the next big breakthrough for the industry.

The quest for green fracking fluids
Some companies believe they are on the verge of such a discovery. ExxonMobil (NYSE:XOM), for instance, says it has developed a new generation of fracking fluids that don't pose a threat to the environment. While the oil major's newly developed concoction hasn't been tested in the field yet, the company assures us that it doesn't contain any toxic chemicals.

Similarly, Halliburton (NYSE:HAL) has developed a green fracking fluid that uses ingredients sourced from the food industry. Halliburton claims that the product, called CleanStim, provides an "extra margin of safety" to people, animals, and the environment in the event of a spill. To prove that the product is truly harmless, a Halliburton executive actually took a sip of CleanStim during an industry event last year.

Besides the companies that actually do the fracking, smaller specialist firms are also making impressive strides in greening the fracking process. For instance, Austin, Texas-based Chem Rock Technologies has developed fracking fluids that it claims do not pose a threat to water supplies even in the event of a spill, while Rapid Drilling Fluids, also based in Austin, has developed biodegradable drilling fluids.

Investor takeaway
As anti-fracking hysteria continues to grow, the need to develop an environmentally safe fracking fluid is more pressing than ever. If ExxonMobil, Halliburton, and others can demonstrably prove that their new concoctions are not harmful to the environment, it would be a massive achievement for the industry and could provide a much-needed boost to its reputation as a poor steward of the environment.