| N-gram | Ontology |
| air pollution | biofuels |
| bio-diesel | biofuels |
| bio-energy | biofuels |
| bio-fuel | biofuels |
| bio-fuels | biofuels |
| biodegradable | biofuels |
| biodiesel | biofuels |
| biodiversity | biofuels |
| bioenergy | biofuels |
| biofuel | biofuels |
| biofuels | biofuels |
| biological diversity | biofuels |
| collectors? | biofuels |
| coppices? | biofuels |
| cost-sharing | biofuels |
| diesel engine | biofuels |
| dioxins? | biofuels |
| drinking water | biofuels |
| eco-efficiency | biofuels |
| eco-labels? | biofuels |
| ecosystem | biofuels |
| electronic waste | biofuels |
| emmisions? reduction | biofuels |
| emulsification | biofuels |
| emulsions | biofuels |
| emulsions? | biofuels |
| energy balance | biofuels |
| energy development | biofuels |
| energy efficient | biofuels |
| energy efficienw+ | biofuels |
| energy equipment | biofuels |
| energy ratios? | biofuels |
| energy reduction | biofuels |
| energy star program(me)? | biofuels |
| energy storage | biofuels |
| energy strategies | biofuels |
| energy strategy | biofuels |
| energy use | biofuels |
| energy window | biofuels |
| engine wear | biofuels |
| environmental quality | biofuels |
| environmentally sustainable | biofuels |
| ethanol | biofuels |
| ethanol made from grain | biofuels |
| ethanol made from stems of plants | biofuels |
| fresh water | biofuels |
| freshwater | biofuels |
| fuel consumption | biofuels |
| fuel efficiency | biofuels |
| fuel pump | biofuels |
| fuel pump sensor | biofuels |
| fuel pumps? | biofuels |
| fuel quality | biofuels |
| gaseous biofuel | biofuels |
| government requirements? | biofuels |
| greenhouse gas | biofuels |
| greenhouse gas(es)? reduction | biofuels |
| greenhouse gases | biofuels |
| heating systems? | biofuels |
| higher energy efficiency | biofuels |
| hydropower | biofuels |
| increase productivity | biofuels |
| landfill | biofuels |
| liquid biofuel | biofuels |
| liquid effluents? | biofuels |
| living conditions | biofuels |
| lower water usage | biofuels |
| methane | biofuels |
| methanol | biofuels |
| mineral diesel | biofuels |
| mortality | biofuels |
| municipal waste | biofuels |
| nuclear waste | biofuels |
| oil waste | biofuels |
| organic certification | biofuels |
| packaging waste | biofuels |
| pesticides? | biofuels |
| pollution control equipment | biofuels |
| pollution prevention | biofuels |
| poverty | biofuels |
| recyclable | biofuels |
| reduction in usage | biofuels |
| risk-sharing | biofuels |
| sanitation | biofuels |
| sensor | biofuels |
| solar | biofuels |
| solar collectors? | biofuels |
| solar energy | biofuels |
| solar generated electricity | biofuels |
| solar heating | biofuels |
| solar water | biofuels |
| solid biofuel | biofuels |
| solvent to vegetable oil ratio | biofuels |
| space heating | biofuels |
| species | biofuels |
| straight vegetable oil | biofuels |
| sugars as fuels | biofuels |
| sustainability | biofuels |
| sustainable | biofuels |
| sustainable development | biofuels |
| sustainable energy | biofuels |
| torque | biofuels |
| toxic waste | biofuels |
| transesterification | biofuels |
| trombe wall | biofuels |
| used vegetable oil | biofuels |
| vegetable carbohydrates | biofuels |
| vegetable oil | biofuels |
| viscosity | biofuels |
| viscosity reduction | biofuels |
| waste cars? | biofuels |
| waste disposal | biofuels |
| waste management | biofuels |
| waste minimization | biofuels |
| waste oil | biofuels |
| waste production | biofuels |
| waste recycle | biofuels |
| waste reduction | biofuels |
| waste streams? | biofuels |
| waste systems? | biofuels |
| waste transportation | biofuels |
| waste vegetable oil | biofuels |
| waste water | biofuels |
| waste water treatment | biofuels |
| water contamination | biofuels |
| water efficiency | biofuels |
| water heating | biofuels |
| water pollution | biofuels |
| water scarcities | biofuels |
| water scarcity | biofuels |
| water supplies | biofuels |
| water supply | biofuels |
| water treatment | biofuels |
| water usage | biofuels |
| white spirit | biofuels |
| wind energy | biofuels |