As bright minds around the world look for new ways of producing energy, a host of interesting and in some cases novel sources are being investigated and brought to market.
Here, CNBC takes a look at some new ideas that have caught the eye.
U.K. business Brackenburn produces "brackettes", made from bracken that it shreds and compresses into briquettes which the company says produce more heat when burnt than oak.
London based bio-bean is harnessing the energy potential of everyone's favorite morning pick me up: coffee.
"We've industrialized the process of turning waste coffee grounds into a bio-diesel and a biomass pellet product," Arthur Kay, CEO of the business, has previously told CNBC.
Edinburgh-based Celtic Renewables is taking the by-products of whisky production and using them to create a next-generation biofuel.
"Biobutanol is on a par with petrol, it's energy equivalent virtually to petrol," Mark Simmers, Celtic Renewables' CEO, previously told CNBC.
The Bio-Bus was designed to run on biomethane gas from "food, sewage and commercial liquid wastes" according to recycling and renewable energy business GENeco.
The Sol-Char toilet uses concentrated solar energy to turn human waste – solid and liquid – into useful and sellable end products such as solid fuel, fertilizer and heat.
The toilet was designed by a team at the University of Colorado, Boulder.
In 2015, researchers at the University of the West of England announced that they had developed a wearable energy generator powered with urine.
Miniaturized microbial fuel cells were "embedded" into a pair of socks.
When a user walked, their urine was pumped, fueling the fuel cells and powering a wireless transmitter that sent a signal to a PC.
The U.S. Department of Energy has said that the genetic diversity from the many varieties of algae presents researchers with "an incredible number of unique properties that can be harnessed to develop promising algal biofuel technologies."
In 2012, the National Research Council of Canada (NRC) flew what it described as, "the first civil jet powered by 100 percent unblended biofuel."
The biofuel used came from what the NRC described as oilseed crops that had been commercialized by Canada's Agrisoma Biosciences.
Last year, Alaska Airlines announced one of its commercial flights had used sustainable fuel made from "forest residuals."
The fuel, according to the Washington state-based airline, was composed of the stumps, limbs and branches left over after the harvesting or thinning of managed forests.
U.K.-based SEaB Energy is using compact anaerobic digestion systems in shipping containers to turn organic waste – food – into energy in the form of biogas, which is used to fuel a combined heat and power engine.