Renewable Energy and Cogeneration Flashcards
6 cards from real CEM practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Renewable Energy and Cogeneration flashcards as text
Thermal energy storage (TES) paired with a chiller plant saves energy cost (not necessarily energy) by:
Answer: Shifting chiller operation to off-peak hours when electricity rates are lower
TES allows chillers to make ice or chilled water at night during off-peak low-rate periods, then discharge stored cooling during peak daytime hours when electricity is expensive.
Biogas produced from anaerobic digestion of organic waste can be used in CHP systems to:
Answer: Generate electricity and heat from a renewable fuel source, reducing fossil fuel use
Biogas (primarily methane) from landfills, wastewater treatment, or agricultural operations can fuel CHP engines or turbines, producing renewable electricity and heat that offset fossil energy purchases.
On-site solar PV reduces a facility's demand charges when:
Answer: Solar generation coincides with and offsets the facility's peak demand periods
Demand charges are based on peak 15-minute or monthly demand; solar only reduces demand charges if it is generating during the facility's peak demand interval, which often aligns with afternoon solar peaks.
A power purchase agreement (PPA) for renewable energy allows a facility to:
Answer: Purchase renewable electricity at a fixed rate from a developer who owns and operates the system
In a PPA, a third-party developer owns the renewable system (often on the customer's site), and the facility purchases the output at a fixed or escalating contractual rate, avoiding capital investment.
Renewable Energy Certificates (RECs) represent:
Answer: The non-energy environmental attributes of one megawatt-hour of renewable electricity generation
RECs (also called SRECs or Green Tags) are tradable certificates representing the environmental attributes of 1 MWh of renewable generation, separate from the physical electricity commodity.
The primary challenge with integrating high levels of variable renewable energy (solar and wind) into the grid is:
Answer: The intermittent and non-dispatchable nature of output creates grid balancing challenges
Solar and wind output varies with weather and time of day; high penetration requires flexible resources (storage, demand response, dispatchable generation) to balance supply and demand in real time.