“The cleanest megawatt is the one never used,” the saying goes. When it comes to energy efficiency and energy conservation, this saying directly applies. When it comes to demand response, this saying does not directly apply. Demand response rarely results in a significant reduction in energy use because load is usually shifted to off-peak hours or substituted by a backup generator. Does that sound clean to you?
Don’t get me wrong. I am a huge demand response advocate. Without more demand response, growth in renewable energy will be severely constrained. Unless electricity demand responds with changing sun and wind patterns throughout the day, we will never be able to rely on those sources for energy. I will be writing about this benefit of demand response in future articles. For this article, I try to debunk the myth that demand response is clean so that we can move on to the true benefits of demand response in later articles.
Do demand response participants shift load?
As a demand response program evaluator, my first priority is to determine the impact of demand response programs during curtailment hours. My second priority is to determine how much load is shifted outside of curtailment hours. I have evaluated many types of demand response programs from residential air conditioning load control to large commercial and industrial programs. Although certain individual customers may not shift load, the aggregate impact for all customers that participate on a given day always shows load shifting. Net energy usage for the day is often slightly lower, but this slight decrease a few times a year is not significant when compared to the reductions achieved by energy efficiency and energy conservation programs.
If participants do not shift load, what do they do?
Sometimes it may seem like certain individual customers do not shift load, but because of backup generation, it is difficult to tell. Many participants simply turn on their backup generator when they are required to curtail load. In these situations, participants do not shift load outside of curtailment hours because there is no load to be shifted. If a participant turns on a backup generator and continues with business-as-usual, their utility metered load suggests that they curtailed and did not shift load, but in fact, they did not even curtail.
What about peaking generators?
Many proponents of demand response are willing to concede that load shifting occurs, but still focus on the less important benefits of demand response. Another argument that I often hear is that, yes, load is shifted, but at least it is shifted away from dirty peaking generation. Peaking generation is dirty when compared to many resources, but base load generation in the United States during off-peak hours is usually coal, which is not clean.
If demand response is not clean, why do we often hear demand response advocates say, “The cleanest megawatt is the one never used?” When it comes to public relations, it’s just easier to bundle demand response with energy efficiency and energy conservation. Instead of explaining all of the ins and outs of demand response, it’s easier to just tell customers, “It reduces energy use. Be green.” I don’t necessarily disagree with this approach for general public relations as long as it leads to further participation in demand response programs.
The issue is that those of us in the industry need to understand how we are all interrelated instead of working in silos. If demand response facilitates the integration of renewables, proponents of sun and wind power should also understand and promote demand response. Similarly, those on the demand side need to understand supply side issues and concerns. After all, if you remember from economics 101, supply and demand have to intersect at some point.