Related by context. Frequent words. (Click for all words.) 59 compressed hydrogen 58 metal hydride 56 ramjet 53 hydrogen 53 gaseous hydrogen 53 liquid propellant 52 algae biomass 52 dry sump 51 kWh lithium ion battery 51 B# biodiesel [002] 51 cell SOFC 51 gaseous fuels 50 UUV 50 electrolyser 50 ultra capacitors 50 CNG compressed natural 50 ActiveE 49 AuraGen 49 propulsion 49 Voltec 49 electrolyzer 49 hydride 49 electric drivetrain 49 electric propulsion 49 rotary engine 49 scramjet engine 48 J 2X 48 gasifiers 48 5kW 48 solid propellant 48 ZPE 48 sodium borohydride 48 algal biomass 48 fuel 48 turbofan engine 48 Hythane 48 biocrude 48 conventional internal combustion 48 scramjets 48 rechargeable lithium battery 48 reactants 48 urea injection 48 #.#kW [002] 48 liquid hydrogen 48 subcritical 48 unpowered 48 1kW 47 naturally aspirated engine 47 volt lithium ion battery 47 spark ignition 47 evaporative emissions 47 super capacitors 47 alkanes 47 conventional combustion engine 47 fast pyrolysis 47 PHWRs 47 lithium ion polymer 47 hydrogen internal combustion 47 biofuel blends 47 CNG refueling 47 autogas 47 FeRAM 47 stoichiometric 47 turbojet 47 Lithium ion 47 Biobutanol 47 Variable Cylinder Management 47 brushless motor 47 radioisotope 47 porphyrin 47 Ti VCT 47 V# TDI 47 diesel 46 electrically driven 46 F CELL 46 ceria 46 Ecotec engine 46 electrochemical reaction 46 electric powertrain 46 dynamometers 46 reciprocating engines 46 propellant 46 ultracapacitors 46 Hydrogen Fuel 46 ECUs 46 gas chromatograph 46 lignocellulosic biomass 46 PEM fuel 46 combustion turbine 46 hydrogen fuel 46 variable valve 46 microchannel 46 #.#L diesel 46 Mobion 46 #kWh [002] 46 powerplants 46 EKV 46 compressed air 46 methyl ester 46 inertial guidance 46 Dumesic