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With DER capacities selected, a full accounting of the benefits of the EcoBlock microgrid system can be quantified based on results from DER-CAM. The following tables include summary metrics for DER capital investment (Table 3-7), annual energy costs (Table 3-8), energy and demand performance (Table 3-9), and microgrid carbon dioxide (CO2) emissions (Table 3-10).

These are the results from the DER capacities selected above and applied to the “most likely”

reference case.

Table 3-7 simply shows the capital costs for the selected DER capacities.

Table 3-7: Capital Costs for DER Deployment Based on Selected Capacities

Source: UC Berkeley

To translate these capital costs into a cost of power from the EcoBlock microgrid, the analysis used DER-CAM to calculate an annualized DER cost, based on variable investment costs

($3500 per kW PV, and $375 per kWh storage), assumed lifetimes, interest rate, and operations and maintenance costs. The annualized DER cost was then divided by the annual production to derive a cost per kilowatt-hour for the EcoBlock power.

The Oakland EcoBlock’s proposed DER portfolio would allow it to reduce costs through a number of operational strategies: self-generation with PV, energy arbitrage when rate

differences are present, demand management when demand charges are present, reduction in transportation fuel costs through smart EV charging, and revenue for exporting excess PV.

DER-CAM optimized each of these strategies holistically to create an operations strategy that minimizes total costs. The results of this strategy are given in Table 3-8, representing the impact of the DER portfolio applied to the block after the homes have had energy retrofits and electrification of major end uses. As the table shows, the DER are capable of reducing electricity costs by nearly $40,000 per year versus the same load profile served only by a utility

connection, representing a 57 percent cost reduction. In addition to these savings, the EcoBlock system also would generate over $5,000 in revenue from PV exports, and with the replacement of 24 vehicles with EVs, reduce annual gasoline costs by nearly $30,000. Note that this analysis assumes 30 miles per gallon for the vehicles being replaced, and gasoline costs of $3 per gallon, which generates a conservative estimate for this savings figure.

Table 3-8: Annual DER Energy Cost Performance Metrics

Source: UC Berkeley

The energy performance of the Oakland EcoBlock can be explored in the energy consumption and provision metrics of Table 3-9. Total annual electricity consumption, which includes EV charging, is approximately 500 MWh, while total generation from the PV array is approximately 444 MWh. This means that 87 percent of the EcoBlock’s electricity demand could be supplied by the PV arrays (which can also be expressed as a “provision-to-consumption ratio” of 0.87). Note that this metric relates indirectly to EcoBlock’s zero net energy (ZNE) performance, but is not a direct measure of ZNE, because the boundaries do not include all energy consumption within the block (such as remaining internal combustion vehicles).

Examining the end-use destinations for PV generation, it appears that a large fraction

(82 percent) would be used locally, while the remaining fraction would be exported. Exports would largely occur during summer and fall seasons, when insolation is high but total loads are low. In winter, when electric heating loads increase and insolation falls, there typically would not be much excess generation for export.

Table 3-9 also shows changes to peak demand. Recall that in the “most likely” scenario, the tariff (A-10) includes a demand charge. As such, the microgrid controller would be incentivized to reduce peak demand levels. Table 3-9 shows a peak observed demand of 93 kW—or 20 kW lower than the same loads without DERs. Note that the no DER case also does not include EVs, meaning that the EcoBlock microgrid would be able to reduce peak demand by nearly

20 percent while also adding charging loads from 24 EVs.

Peak demand under tariffs without demand charges is likely to be higher than in the A-10 tariff scenario. See Figure 3-28 for evidence of this. It should be clear, however, from the results of the “most likely” scenario, that the EcoBlock system has adequate capability to eliminate demand spikes when the right incentives are present.

Table 3-9: Annual DER Energy and Demand Performance Metrics

Source: UC Berkeley

Finally, the changes to CO2 emissions from the Oakland EcoBlock microgrid deployment are outlined in Table 3-10 and Figure 3-32. Reductions in emissions from the homes would be caused by three factors: (1) consumption reductions due to efficiency measures,

(2) substituting electricity for space and water heating currently powered by natural gas, and (3) replacement of most PG&E-supplied electricity with PV generation on site. Here, the carbon intensity of the replaced electricity was assumed to be 0.28 kilograms (kg) CO2 per kWh, which is a standard value used by the California Energy Commission. For vehicles, reductions in emissions from gasoline would be due to a substitution in vehicle miles traveled from internal combustion vehicles to EVs. The carbon intensity of gasoline was assumed to be 8.89 kg CO2

per gallon.¹⁷ The conversion to EV charging from the Oakland EcoBlock microgrid would reduce the CO2 emissions from passenger vehicles on the EcoBlock by about one-third. Additional reductions would be due to export of excess PV generation, which would replace generation originating from the grid. If we assume that the 24-vehicle EV fleet would replace all the conventional vehicles at the Oakland EcoBlock site, then this system would produce a 61 percent reduction in CO2 emission from onsite energy use. If the EV fleet only replaced some fraction of the total transportation needs, then the percentage reduction in CO2 would be smaller.

Table 3-10: Annual EcoBlock Microgrid CO2 Emissions Performance Metrics

Source: UC Berkeley

Figure 3-32: Annual CO2 Reductions Including All fuels (Electricity, Natural Gas, Gasoline)

Source: UC Berkeley

Performance Under Varied Inputs

The values above represent only the performance of the selected DER portfolio under the inputs of the “most likely” scenario. However it is entirely possible that this exact scenario is not the one the Oakland EcoBlock will face when deployed. As such, it is important to

understand how the selected DER portfolio might perform under different circumstances.

From a technical perspective, the system is capable of achieving the same level of energy and emissions performance, given that the same capacities of generation and storage are present.

Economic performance is likely to be the most varied if conditions change. To explore this, the team generated Figure 3-33 to show the annual net cost savings for each tariff, export, EV fleet, and load scenario discussed in this analysis. This metric includes electricity cost reduction, PV export revenue, and avoided fuel costs from EVs versus the same conditions without DERs or EVs. The savings estimate from the “most likely” scenario is also plotted for reference in each subplot, to show whether savings increase or decrease under the specific conditions.

Figure 3-33: Annual Net Cost Savings From DER Deployment

Includes electricity costs savings, PV export revenue, and avoided fuel costs from EVs. Dotted lines indicate annual net savings under the “most likely” reference case.

Source: UC Berkeley

Net savings increase with the size of the EV fleet, due to increased avoided fuel costs. Under every scenario, charging EVs—either from PV generation or utility electricity–is lower cost than the assumed cost of gasoline on a mileage basis. Recall from Table 3-8 that roughly 37 percent of net annual cost savings come from avoided fuel costs from EVs.

Savings are also higher for the higher load Scenario 1, since a larger fraction of PV generation can be used to replace utility purchases, which has higher value per kilowatt-hour than export in most cases. Net savings also increase as export prices increase under CCA export models.

Finally, savings appear to be highest under the flat-rate (E-1) tariff, then somewhat lower for the

residential TOU (E-6) tariff, and then lowest for the commercial TOU (A-10) tariff. This order corresponds to a highest to lowest ranking of average energy rates.

If EV fleet size were held constant at the reference value of 24 vehicles, annual net savings would be pretty consistent: $69,000–$104,000 (median: $81,000) for retrofit Scenario 1, and

$59,000–$87,000 (median: $70,000) for retrofit Scenario 2. This indicates that the DER capacities selected for EcoBlock are expected to perform reasonably well economically for nearly all of the potential circumstances in which it might be deployed.