REP Cheat Sheet 2026

The 30 highest-yield REP facts, distilled from real exam questions. Print it, save it as a PDF, or study it here — free, no sign-up.

1. What is 'energy payback period' and why is it relevant to environmental assessment of renewables? → The time needed for a renewable system to generate the energy used in its production
2. How does life cycle assessment (LCA) benefit sustainability? → By assessing environmental impacts throughout the product life cycle
3. What is the significance of a wind turbine's hub height in energy production? → Greater hub height accesses higher, more consistent wind speeds due to wind shear
4. Which geophysical survey method is most commonly used to locate subsurface geothermal reservoirs before drilling? → Magnetotelluric (MT) resistivity surveying
5. How do energy efficiency standards impact buildings? → They reduce energy use and increase performance
6. What is the primary technical reason that integrating high percentages of variable renewable energy (VRE) into a grid requires increased flexibility resources? → VRE output fluctuates with weather and does not inherently match demand patterns
7. What is the purpose of a combiner box in a large PV array? → Combine multiple string circuits and provide overcurrent protection
8. What does the 'specific yield' metric represent for a wind turbine installation? → Annual energy production per kW of rated capacity
9. Which atmospheric layer is most relevant to wind turbine operation and resource assessment? → Atmospheric boundary layer
10. What is the primary advantage of variable-speed wind turbines over fixed-speed designs? → Ability to operate at optimal tip-speed ratio across a wider wind range
11. What is the function of a nacelle in a horizontal-axis wind turbine? → Houses the gearbox, generator, and drive train components
12. Why are renewable portfolio standards (RPS) significant? → They promote renewable energy adoption
13. What is the primary purpose of energy policy? → To ensure a reliable, affordable, and sustainable energy system
14. What is the main environmental advantage of run-of-river hydropower compared to reservoir-based hydropower? → Significantly less disruption to river flow and ecosystems
15. Which renewable energy project development risk is best characterized as 'basis risk'? → The difference between the PPA price and actual market prices at the delivery point
16. Which risk is best mitigated through an interconnection queue study conducted early in project development? → Unexpected grid upgrade costs that could render a project uneconomical
17. What environmental concern has led some states to require decommissioning bonds for wind and solar projects? → Ensuring funds exist for proper removal and site restoration when projects end
18. What is the primary purpose of a 'power purchase agreement' (PPA) in renewable energy project development? → To secure long-term revenue by locking in the price a buyer pays for electricity
19. In wind resource assessment, what does P90 production estimate mean? → There is a 90% probability that actual production will meet or exceed this value
20. Which of the following is a primary challenge associated with integrating large-scale renewable energy into traditional power grids? → Reduced system inertia
21. Which U.S. regulatory body has authority over the siting of offshore wind projects in federal waters (beyond 3 nautical miles)? → Bureau of Ocean Energy Management (BOEM)
22. Soiling losses on PV panels are primarily caused by which of the following? → Dust, dirt, bird droppings, and other surface deposits
23. What is a primary benefit of using solar photovoltaic (PV) systems? → They provide renewable, clean energy with minimal emissions
24. In a landfill gas-to-energy (LFGE) project, what is the typical range of landfill gas methane concentration? → 45–60%
25. Which section of the U.S. tax code governs the Production Tax Credit (PTC) for renewable electricity generation? → Section 45
26. Which policy mechanism under the 2022 Inflation Reduction Act specifically expanded incentives for biogas and biomethane projects in the U.S.? → Section 45Z Clean Fuel Production Credit covering biomethane sold as transportation fuel
27. Which environmental concern is most commonly associated with large-scale hydropower dams? → Disruption of fish migration and aquatic ecosystems
28. Which type of solar concentrating technology uses a parabolic dish to focus sunlight onto a Stirling engine at the focal point? → Dish-Stirling system
29. In a doubly-fed induction generator (DFIG) wind turbine, what does the 'doubly-fed' refer to? → Electrical power fed to both the stator and rotor windings
30. Which co-digestion feedstock is most commonly added to municipal sewage sludge to significantly boost biogas yields? → Food waste and fats, oils, and greases (FOG)