UC Davis Microgrid. Jared Balavender, DTU Katarina Knezovic, DTU Adrian Unkeles, UCSC Yingying Zheng, UCD

Transcription

1 UC Davis Microgrid Jared Balavender, DTU Katarina Knezovic, DTU Adrian Unkeles, UCSC Yingying Zheng, UCD

2 Problem Statement Client: UC Davis Goal: Carbon Neutral by 2025 Main limitation No net metering Considerations: Demand reductions and energy efficiency Increased PV generation Storage via Batteries Demand response Rescheduling the cooling system

3 Base scenario Consumption profile for 2012 Total demand: 229,443 MWh Baseload: 165,564 MWh 16.3 MW of PV 32,725 MWh Equals 14.3% of current total demand 19.8% of baseload 45 Total UCD consumption in Power (MW) % of annual energy consumption goes to base load Time of year (h)

4 Assumptions PV efficiency degradation of 0.25% per year No possibility of net metering 2014 data equivalent to 2012 data Campus cooling system electricity usage remains constant Cooling system consists of 8 absorption chillers with total rated power of 12.6 MW at an average efficiency rate of 0.7 kw/ton Electricity price is 0.07$/kWh and constant throughout project period Baseload remains same percentage of demand Refined Scope: Optimize use of doubling PV generation

5 Analyzed Cases UC Davis doubles PV nominal capacity to 32.6 MW and Two scenarios for the campus consumption profile: 1) no decrease base scenario Consumption the same throughout 10 years 2) 5% decrease in annual demand through project period Total demand in 2025: 144,607 MWh Baseload in 2025: 104,305 MWh

6 Excess PV generation Estimated production for 32.6 MW photovoltaic array 30 Estimated PV Power Generation 25 Power (MW) Exceeds the demand for 1733 hours in the base scenario Time of year (h)

7 Excess PV generation Scenario with no consumption decrease Excess PV generation (MWh/year) Year Loss of PV generation % % % % % % % % % %

8 Excess PV generation Scenario with 5% consumption decrease every year Excess PV generation (MWh/year) Year Loss of PV generation % % % % % % % % % %

9 Value of lost energy Year Value of lost generation for Scenario 1 Year Value of lost generation for Scenario 2 1 $91,362 1 $91,362 2 $88,808 2 $145,708 3 $86,306 3 $214,952 4 $83,834 4 $297,432 5 $81,409 5 $392,334 6 $79,055 6 $498,421 7 $76,763 7 $613,301 8 $74,517 8 $737,064 9 $72,324 9 $866, $70, $998,420 TOTAL $804,551 TOTAL $4,855,881 Assuming 0.07$/kWh -> even larger losses if the price increases

10 Potential technologies for utilizing excess energy Two different battery technologies simple cost-analysis conducted case of no consumption decrease with all excess energy stored in the batteries -> not cost effective Customer demand response indirect strategies not cost-effective due to low electricity price Temporary load shifting changing the operation schedule of cooling chillers the most feasible solution

11 Current cooling system

12 Rescheduling cooling chillers Scenario 1 Load shifting is effective for the months of April through October. Operation of chillers in most inefficient temperature range still leads to net cost benefits because the PV provides all the energy at that time. Scenario 2 Load shifting is effective throughout the year, with duration and frequency peaking in the summer MW peak excess PV in year 10

13 CO2 emissions If all the excess energy was used to power the chillers during the day, significant CO2 savings would be made Year No consumption change Excess generation GHG Emission used by cooling (Ton CO2e) system (MWh) 5% decrease in consumption every year Excess generation GHG Emission Year used by cooling (Ton CO2e) system (MWh) 1 1, , , , , , , , , , , , , , , , , , , , , , , , , , , TOTAL 3, TOTAL 21,504.61

14 Conclusion and recommendations Excess energy curtailment No decrease in consumption: $804,551 lost 5% decrease in consumption: $4,855,881 lost Batteries and customer demand response are not cost-effective for storing the excess energy Changing the operation schedule for the chillers Chillers rated power higher than maximum excess peak in both scenarios Feasible to operate the chillers even with lower efficiency rates ZNE goal unattainable unless net-metering restriction is lifted Future works recommendations Analyze chillers energy efficiency when shifting the operation from night to day Reduce the base load through energy efficiency measures Consider second-hand batteries

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