Enermetrics conducted a study on 5671 high schools across the USA to determine which technologies are best to reduce energy costs and emissions. The results are presented in these charts.
When comparing the simple payback to the cost savings, it is clear that scenarios 99 and 111 have the best savings. These are CHP (natural gas) in California and Hawaii respectively - where the electricity rates are very high.
However, when we look at GHG savings vs NPV, scenario 99 (California) shows a very poor response - because the California grid is relatively clean and there is limited use for waste heat in the summer. Scenario 111 (Hawaii) has reasonable GHG savings as the grid there is relatively dirty.
In most cases, solar PV (yellow bubbles) out performs CHP (small purple bubbles). This is due to the operating schedule of schools (and the need for electricity) aligns well with the solar generation potential. Further, there is limited need for CHP heat in states with warmer weather.
Fuel cells (blue) have the lowest financial performance as the cost of hydrogen is still too high. Further, the availability of hydrogen is still a challenge.
Upgrading heating systems with high efficiency condensing boilers (red bubbles) has a very short simple payback but does not have material cost savings.
There are many factors to consider when designing your energy cost and emissions reduction strategy. You need to consider the cost of energy, grid carbon emissions, transmission and delivery costs, and many other factors. It gets complex.
If you need help, please reach out.
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