Filling your gas tank with algae may be getting closer.

Startup Sapphire Energy announced this week that it has produced a 91-octane "green crude" using algae grown from wastewater. A number of other companies are also developing algae-based fuel technologies, as Miller-McCune.com chronicled back in February.

Sapphire's product will be entirely compatible with the current energy infrastructure from cars to refineries and pipelines, the company said. Its platform uses sunlight, carbon dioxide, photosynthetic micro-organisms and non-arable land.

Algae is showing increasing promise in the alternative energy community since unlike more commonly available biofuels such as corn-based ethanol, it does not impact food supplies or prices, is completely renewable and has a lower environmental impact because of the way it is produced. Backyard moonshine is attracting investors for similar reasons.

Sapphire has recently raised more than $50 million from venture capital firms. The company reportedly plans to have commercial production operational in three years.