Biomass stores energy primarily as what?
A Chemical energy
B Electrical charge
C Wind momentum
D Nuclear binding only
Answer: A. Chemical energy. Biomass contains chemical energy from photosynthesis.
Anaerobic digestion produces biogas containing methane and what?
A Oxygen only
B Hydrogen peroxide
C Nitrogen oxide
D Carbon dioxide
Answer: D. Carbon dioxide. Biogas commonly contains methane and carbon dioxide.
Gasification converts biomass into what combustible mixture?
A Pure oxygen
B Liquid water
C Syngas
D Nuclear fuel
Answer: C. Syngas. Gasification produces synthesis gas containing combustible gases such as CO and H2.
Biomass combustion releases what useful output?
A Wind torque
B Heat
C PV current
D Geothermal pressure only
Answer: B. Heat. Combustion converts chemical energy in biomass into heat.
Biodiesel is commonly produced by what chemical process?
A Electrolysis
B Transesterification
C Distillation only
D Photovoltaic conversion
Answer: B. Transesterification. Transesterification converts oils or fats into fatty-acid methyl esters.
Hydropower uses water elevation difference called what?
A Head
B Pitch angle
C Solar flux
D Blade ratio
Answer: A. Head. Hydraulic head represents mechanical energy per unit fluid weight.
A Pelton turbine is suited to high head and what flow?
A Lower flow
B Very high flow only
C No flow
D Low head only
Answer: A. Lower flow. Pelton impulse turbines commonly serve high-head, lower-flow sites.
A Francis turbine is a mixed-flow type suited to what?
A Only very low head
B Only tidal flow
C No head
D Medium head range
Answer: D. Medium head range. Francis turbines are used over a broad medium-head range.
A Kaplan turbine is suited to low head and what?
A Low flow only
B High head only
C High flow
D No reservoir
Answer: C. High flow. Kaplan propeller turbines handle low-head, high-flow sites.
Geothermal energy uses heat from what source?
A Solar panels
B Wind shear
C Earth interior
D Combustion gas only
Answer: C. Earth interior. Geothermal systems extract heat stored within Earth.
A geothermal heat pump exchanges heat with what?
A Wind turbine tower
B PV module
C Ocean waves only
D Shallow ground
Answer: D. Shallow ground. Ground-source heat pumps use relatively stable shallow-ground temperature.
A dry-steam geothermal plant sends steam directly to what?
A Solar collector
B Electrolyzer
C Cooling tower only
D Turbine
Answer: D. Turbine. Dry-steam reservoirs supply steam to a turbine.
A binary geothermal plant transfers heat to what?
A Secondary working fluid
B Fuel oil
C Combustion air
D Wind rotor
Answer: A. Secondary working fluid. A heat exchanger vaporizes a secondary fluid with a lower boiling point.
Pumped hydro stores energy by moving water to what?
A Lower pressure pipe
B Cooling pond only
C Turbine blade
D Higher reservoir
Answer: D. Higher reservoir. Pumped storage uses electricity to pump water uphill for later generation.
A fuel cell converts chemical energy directly into what?
A Electrical energy
B Mechanical shaft work only
C Wind power
D Solar heat
Answer: A. Electrical energy. Fuel cells electrochemically produce electricity from fuel and oxidant.
A hydrogen fuel cell’s main product is what?
A Water
B Carbon dioxide
C Sulfur dioxide
D Solid carbon
Answer: A. Water. Hydrogen fuel-cell reaction produces water and heat.
Electrolysis splits water using what input?
A Wind pressure only
B Electrical energy
C Combustion heat only
D Hydraulic head
Answer: B. Electrical energy. An electrolyzer uses electricity to separate water into hydrogen and oxygen.
Green hydrogen is produced using what electricity source?
A Coal electricity only
B Diesel exhaust
C Renewable electricity
D Nuclear waste heat only
Answer: C. Renewable electricity. Green hydrogen is made by electrolysis powered by renewable electricity.
A PEM fuel cell uses which membrane type?
A Ceramic oxide only
B Molten carbonate only
C Alkaline metal plate
D Proton-exchange membrane
Answer: D. Proton-exchange membrane. PEM fuel cells conduct protons through a polymer membrane.
A solid oxide fuel cell operates at what temperature range?
A Cryogenic temperature
B Room temperature only
C High temperature
D Below freezing
Answer: C. High temperature. SOFCs operate at elevated temperatures using ceramic electrolytes.
A biogas digester processes organic matter without what?
A Oxygen
B Water
C Microorganisms
D Heat transfer
Answer: A. Oxygen. Anaerobic digestion occurs without oxygen.
Digestate is the remaining material after what process?
A PV conversion
B Anaerobic digestion
C Wind generation
D Water electrolysis
Answer: B. Anaerobic digestion. Digestate is the nutrient-rich residue from anaerobic digestion.
Hydrogen storage can use compressed gas or what form?
A Solid oxygen
B Steam only
C Liquid hydrogen
D Wind power
Answer: C. Liquid hydrogen. Hydrogen can be stored as compressed gas, cryogenic liquid or in materials.
A hydroelectric generator is driven by what?
A PV inverter
B Turbine shaft
C Electrolyzer
D Fuel cell membrane
Answer: B. Turbine shaft. The water turbine turns a generator to produce electricity.
Wave energy devices extract energy from what motion?
A Underground heat
B Ocean waves
C Wind shear only
D River sediment
Answer: B. Ocean waves. Wave-energy converters capture oscillatory motion and pressure from ocean waves.