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11/29/21 Guest blog by Jeff Inhen, CEO, Michaels Energy
Grid-Interactive Efficient Buildings Are Active Efficiency
If grid interactive efficient buildings are not synonymous with Active Efficiency, they comprise the vast majority of the Active Efficiency pie.
Grid interactive efficient buildings, or GEBs, will help accommodate intermittent renewable solar and wind power generation while minimizing grid and supply-side energy costs. Potential GEB benefits include:
- Accommodating large penetrations of renewable energy by shaping loads to take excess power when it is available, then store it for use when it is not available.
- Energy conservation.
- Less-expensive energy supply.
- More customer control over energy costs.
What are some elements of GEBs? Pictures are worth thousands of words. The graphs below were taken from the DOE’s National Roadmap for GEBs, which the Active Efficiency Collaborative supported. It depicts the various ways buildings and the equipment in them can be used to change the net load of the building and, when aggregated together over hundreds or thousands of buildings, have significant benefits for the grid. Let’s examine each of those methods.
Efficiency measures help to shift the load curve down, therefore decreasing costs, emissions, and improving reliability by reducing the need for peaker power plants. However, it’s important to note that these charts are for demonstration, and that efficiency resources have savings curves that depend on the weather, time of day, production levels, and many other possible factors. An energy efficiency measure or project rarely saves a constant load 24 hours a day. Energy saved concurrently with local or transmission-level peaks is worth far more than energy saved during the valleys of grid demand, when renewables may need to be curtailed.
While shedding can be as simple as turning equipment off or down, interactions between different building aspects impact the net load. Lighting is one example. Powered lighting curtailment saves lighting power, but because lights produce heat, turning them off also saves energy used on air conditioning during the summer. During winter peaks, shutting down lights when it’s minus 15F outside may result in no net impact because the heating system must make up the difference. Here we are just beginning to see how complex this can be. In other shedding events like air conditioner cycling or commercial or industrial cooling curtailments, there will be some rebound or snapback to bring these spaces back in line with normal setpoints.
GEB deployment may be used to flatten a fast grid-scale ramp of demand, such as when the sun sets in a region with gobs of solar generation, but this may again provide no value from a greenhouse gas (GHG) perspective. It may save capital costs by avoiding or delaying peaking capacity, but it may merely shift natural-gas-fired power generation from here to there. So in some cases, GEBs may provide dollar savings, no GHG savings.
There are many ways to shift load, including the snapback case described above. Other methods include electricity storage or storing what electricity is used for, such as moving heat. Batteries would be the predominant electricity storage choice for buildings. Buildings can store and exchange heat with many types of phase change materials (liquid to solid and back) including water, salt water solutions, and hydrocarbons like plant-based fats (e.g., coconut oil). Phase change materials can be used to store and release heat from electricity-generated sources over a range of temperatures from below zero to a thousand degrees.
Modulation is likely the least deployed GEB tool because it is a grid resource that provides very fast response times but over a shorter period. Modulation resources can include batteries, capacitors, and spinning reserves like flywheels to maintain voltage and frequency response for a stable grid. There is no need for these resources to be part of a customer’s building.
Examples of on-site generation include solar photovoltaic, standby generators, back pressure turbines, and combined heat and power. These assets will be needed to provide reliable backup and reserves to enable safe, deep decarbonization.
GEB CHALLENGES AND THE WAY FORWARD
With the five major categories of GEB strategies described above, let’s examine challenges to widespread deployment of these strategies, and then present some solutions.
The Executive Summary of the National Roadmap for Grid-interactive Efficient Buildings notes consumer awareness, complexity, utility interests and regulatory models, and policymaker knowledge as critical issues that need to be addressed.
To summarize challenges from that paragraph:
- Consumer awareness: Many consumers aren’t aware of the revolution taking place in building technology and energy pricing structures to create GEBs, and there’s a long road ahead to not only educate consumers, but truly demonstrate how GEBs benefit them. For example, time-of-use and demand rates may incentivize customers to shave energy demand during peak hours, but consumers need to be aware of what these rates are, when they apply, and be convinced that flucating rates are worth the hassle of switching from flat rate pricing.
- Complexity: This is the biggest issue with GEBs – as noted above, consumers might not see the value in GEBs because they would rather pay one flat price for electricity. But it’s not just perceived consumer complexity: there are complications for markets and policymaking as well – such as the question of how to measure and value GEBs. If Active Efficiency measures in a building allow it to be an asset to the grid, then how is that contribution being recognized?
- Utility interests and regulatory models: The traditional utility business model – which has revenue requirements based on funding operations, equity, and debt financing – does not incentivize utilities to invest on the customer side of the meter for things like GEBs, because as demand shrinks, prices would go up to make up lost revenue. Decoupling prices from sales and other changes to the business structure can help.
- Policymaker knowledge: GEBs need champions in lawmakers. Investing in the necessary R&D and restructuring regulatory models requires policymakers to understand how Active Efficiency can benefit their constituencies and to have the desire to change the status quo.
After reading the description of these challenges and stepping back for a second, these barriers look like something we’ve successfully been able to overcome for almost 40 years: barriers to energy efficiency programs. Deep deployment of GEBs requires the same approach with a little different language. We can do it!