Metrics and Constraints

METRICS & CONSTRAINTS

Problem objectives/how did you define the problem. 

The electric grid is facing two issues – unfavorable renewable energy peaks and a projected significant increase in peak loads due to electric vehicles. Our project seeks to address both of these concerns.

Problem Objectives

  1. Design an economically favorable compressed air energy storage system which can store and release energy generated by renewable sources. 
  2. Scale this energy storage system to meet the user needs of grid operators within the context of projected electric vehicle growth. 

Compressed Air Energy Storage System

Constraints: 

  • Stores and releases energy using compressed air using air turbine thermodynamics.
  • The system’s ability to store and release energy is not time-of-day-dependent.
  • The system’s ability to store and release energy is not geographically-dependent.
  • The CAES system can be implemented in tandem with a renewable energy source.
  • The CAES is an economically viable addition to the energy grid. 

Metrics: 

Performance

Power rating (MW)

Energy/storage capacity (Wh): max amount of stored energy that system can deliver

Charge efficiency (%) stored energy/input energy

Discharge efficiency (%) output energy/stored energy 

Round trip efficiency (%) output energy/input energy

Response time (s) time required to ramp discharge power to rated power

Daily self-discharge (%day) percentage of energy capacity lost to heat/friction/chemical losses

Lifetime (years)

Performance degradations (%year)

Storage duration (s/ms): time between charge and discharge events

Economic

Power capital cost ($/W)

Energy capital cost ($/Wh)

Operating and maintenance cost ($)

Electric Vehicle Charging Stations Electricity Demand Metrics and Constraints

 

Constraints:

  • Stored electricity can be brought onto the grid through aggregation – meaning a group of companies or larger institutions can jointly purchase the storage system and its corresponding energy.
  • The quantity of electricity provided to the grid through CAES is resilient. Storage capacity can adapt and scale itself to meet the net demand of electric vehicles trends now and in the future.
  • Provided electricity can respond to the changing demand of electric vehicles’ lithium batteries – including charge rate and charge output capabilities.

 

Metics:

Performance:

Projected Peak Load (kW or MW)

Load Variability throughout the day (kW/hour-of-interest)

Charger capacity (kW)

Charger speed (kWh)

Economic:

Electricity cost to user (W of charge/USD)

Payback Period (years) – length of time for return on investment to break-even

 

Notes

To reiterate, this project is an attempt to explore a solution to close the discrepancy between energy supply and demand by better leveraging renewables at the times where they are most accessible. This will be done using energy storage to harness solar and wind energy generated throughout the day and night at off-peak hours to then discharge during peak hours in order to alleviate the need to rely heavily on fossil fuels.

The success of this project depends on two main areas. First, to what extent is CAES able to store and release energy for later use? Second, how is our CAES solution an improvement from baseline solutions that are currently implemented?

In other words, is this solution possible? And is this solution an improvement of the status quo? Aboveis a bird eye view of qualitative and quantitative factors by which the success of this energy storage design project will be measured by.