Shifting the Load Curve Since grid marginal emissions are lowest during mid-day, a battery bank can shift the hours of grid draw by charging during these low emissions hours and dispatching to meet the project demand during high emissions hours.
Figure 5 shows the result of implementing the previously discussed dispatch sequence that tracks project demand against the grid emissions profile. By shifting the renewable energy offset period to high GHG intensity hours, a 2 MW battery bank increases the GHG avoidance from 12% to 18% in the 2020 scenario. The impact of the same 2 MW battery bank, using the same dispatch sequence, increases significantly as the relative difference between clean and polluting periods gets more prominent. In the 2030 scenario, presented in the bottom chart in Figure 5, with everything else held constant, GHG avoidance increases over five-fold from 6% to 32%.
ELECTRICITY (kWh)
5000
Grid to Project Battery to Project PV to Project Grid to Battery PV to Battery
4000 3000 2000 1000 0 2500
PV GHG Avoided
2020 GHG (kgCO2E )
2000
Battery GHG Avoided GHG Emissions
1500 1000 500 0 2500
PV GHG Avoided
2030 GHG (kgCO2E )
2000
Battery GHG Avoided GHG Emissions
1500 1000 500 0
Typical Summer Work Week
Figure 5: Hourly energy balance with 2 MW PV and 2 MW battery bank that offset 24% of project energy use [Top], increase the GHG avoidance from 12% to 18% in 2020 [Middle], and a five-fold increase from 6% to 32% in 2030 [Bottom].
Decarbonizing the Built Environment
8
