It goes without saying that water is essential to life on earth — but it's also crucial to the energy industry.
"Energy needs water and water needs energy," Kala Vairavamoorthy, executive director of the International Water Association, told CNBC's "Sustainable Energy".
"When you look at energy production, water is required in every stage of the production cycle," he added. "Water is required for all different forms of energy production, for the production of fossil fuels, biofuels, concentrated solar power."
Vairavamoorthy added that energy was, in turn, "essential" to water production. "Energy is required to extract water, it's required to lift, to move water, and it's required to treat water," he said.
According to the International Energy Agency (IEA) conventional biofuels accounted for roughly 4 percent of global road transport fuel in 2016.
For his part, Vairavamoorthy stressed the importance of water when it comes to the production of biofuels and highlighted the environmental impact.
"On average, the amount of water required to produce one liter of biofuel is the same amount that's required to produce food for a person for one day," he said, adding that the problem with first generation biofuels was that they were competing with food production systems in terms of water and land. This, he explained, was "making food production systems vulnerable."
Second generation biofuels, he added, offered a better solution as they don't compete for water and land with food production systems.
These had "much greater potential" Vairavamoorthy said, highlighting, among other things, waste from agricultural production that could also be used for biofuel production.
The key objective was that biofuel production should not compete with water and land for food production.