Conservation in the Plan Scenarios

Alternate energy efficiency supply curves were developed for three scenarios: Robustness of Energy Efficiency, Paths to Decarbonization, and Analyze the Bonneville Portfolio.

Robustness of Energy Efficiency

Energy efficiency is a priority resource in the Power Act and has been an important component of every power plan’s preferred research strategy. Although there is uncertainty in the amount of achievable technical potential, this uncertainty is not reflected in the supply curves. To understand the impact of this uncertainty, the 2021 Plan includes a scenario exploring potential that is significantly more or less than the baseline curves.

For the “high” achievability, the measures all included the fastest ramp rate (“80 fast”) and the maximum achievability was increased by 15 percent. Note, this results in many lost opportunity measures having a maximum achievability greater than 100 percent. In other words, the high achievability is a proxy for emerging technologies with higher efficiency tiers not included in the baseline curves. The overall 20-year potential was increased by about 20 percent compared to the baseline curves.

For the “low” achievability, the ramp rates are reduced to be two-thirds of the original rate in the early years[1] and the maximum achievability was decreased by 15 percent. The overall 20-year potential was decreased by about 15 percent compared to the baseline curves.

The supply curve workbooks for the high and low achievability can be found here.

Another source of uncertainty is the amount of capacity reduction achieved through energy efficiency and its value to the resource strategy. This is determined based on the shape of the efficiency savings. However, data informing these shapes is mixed quality. To help understand the capacity impact on efficiency, the 2021 Plan varied the relative contribution of capacity and energy by quarter. Specifically, the peak impact was modified to be numerically equivalent to the energy impact for the fall/winter season, the spring/summer season, and for all seasons. In other words, the peak capacity to energy impact ratio is set to be 1.0 for the seasons separately and for the entire year to gauge the importance of energy efficiency in reducing both winter and summer peak loads.

Paths to Decarbonization

In the paths to decarbonization scenario, one area of exploration included in the 2021 Plan is how much greenhouse gases will be reduced by electrifying end uses (e.g., HVAC, water heating, cooking). For energy efficiency, as end uses are electrified there will be more potential from improving the efficiency of those units. For example, a gas water heater might convert to an electric storage water heater. The efficiency improvement will be to have the end-use customer instead install a heat pump water heater. Thus, the energy efficiency is significantly increased in a highly electrified system than the baseline system.

In developing the supply curves for this scenario, the electrification assumptions were largely aligned with the demand forecast. Assumptions include:

1. All new construction is 100% electric
2. No new fossil fuel equipment is available. So, for example, as existing gas furnaces burn out and need to be replaced, they will be replaced with an electric unit with a market-average efficiency. The rate of turnover is aligned with the demand forecast.
3. The efficiency will occur at the time of replacement for the electrified equipment and not be constrained by ramp rate assumptions.
4. More efficiency will also be available for retrofit measures (e.g. weatherization) as those buildings heating systems are electrified.
5. Maximum achievability is increased by 15 percent, relative to the baseline to reflect additional investment in electrical efficiency research and development (similar to Robustness of Energy Efficiency scenario).
6. For the Energy 2020 model, the supply curves were extended to 2050.

Under this scenario, the total achievable technical potential increased to approximately 8,200 average megawatts by 2041 and up to nearly 10,000 average megawatts by 2050. The paths to decarbonization workbooks are available here.

Analyze the Bonneville Portfolio

Energy efficiency can reduce Bonneville’s obligations by reducing its utility customer loads. To estimate the amount of efficiency available for Bonneville, the 2021 Plan supply curve includes potential savings for all of Bonneville’s customers and not limited by its obligation (i.e. potential across all of Seattle City Light end-use customers, even though Bonneville provides SCL only about half of its load). The portion of the total efficiency potential that reduces Bonneville’s obligation is accounted for in the resource strategy analysis.

To develop the efficiency supply curves for Bonneville, the Council started with the regional supply curves. Then, the regional number of units (homes, square feet of building, acres irrigation, and industrial load) was reduced by the approximate portion within Bonneville territory. The table below provides the portion of the region represented by the Bonneville customer utilities and the source for this estimation. Note, a number of these were developed by Bonneville for its 2018 conservation potential assessment.

The Bonneville supply curve, differentiated by sector, is shown in the figure below and the workbooks can be found here. Additional information on comparing Bonneville to the region can be found in this presentation.

Efficiency Supply Curve for Bonneville Territory

[1] In order to have the ramp rates encompass 100% of the maximum achievable, the ramp rates are increased in the later years to make up for the early year deficit. This cross over depends on the particular ramp rate.