Our Findings

our findings tabulated

Figure 1: Our Results Matrix

Comparing our results for a new-build district, initially only comparing CHP, Boiler and Electrical (in today's energy mix) systems, we found that CHP was ranked highest overall, followed by Boiler and Electrical systems. This was due to the following factors:

  1. For an electrical system powered by fossil fuels, the energy and exergy scores were very poor.
  2. Additionally, because of the emissions from electricity production, the "emissions" score for the Electrical system was the worst possible.
  3. CHP had an excellent score for "subsidies and income" due to the numerous subsidies available as well as the potential to sell electricity, as well as receiving an equally excellent score for "end user cost" due to the value an end user would receive from such a system.

When we then compared these systems to an Electrical system powered by 100% renewables, we found that this system was now suddenly extremely competitive with the CHP system, due to the following:

  1. Because the electricity now comes from a renewable source, and this source is abundant and free, energy and exergy efficiencies were greatly improved.
  2. The emissions score went from the worst to the best possible.
  3. The "cost for end user" received a better score because we predicted that in a future scenario, using storage, the system would be able to take advantage of excesses in energy at cheaper rates and thus save the user money.
  4. The "subsidies and income" score was improved as we predicted that in a future where the electricity supply is 100% renewable, there would be government subsidies available to encourage people to stop using gas central heating and to use electrical instead.

Comparing these same systems in a retrofit scenario, it was now found that an electrical system powered by 100% renewable was the most favourable system (followed by CHP, Boiler and electrical powered by today's energy mix). This was because, although all systems scored lower overall than for a new build, due to the necessity to build infrastructure or replace components, the pipe-based systems (CHP and Boiler) now scored badly in the "impacts" category due to the disruption and noise caused during the construction of the required infrastructure.



Conclusions

From the above results, we drew the following conclusions:

  1. If using a boiler based system, the boiler must be sized correctly as finances can be quite tight with this kind of system
  2. Currently, if there is an electrical demand to be met, CHP is the best option. Otherwise, a boiler system is best.
  3. In today's energy mix, even with the most modern technology available, electric district systems cannot compete with pipe based systems.
  4. However, our final conclusion, and recommendation to the industry, is that we foresee that as the energy mix shifts towards being more and more renewable, there will be a point in the not too distant future in which electrical systems become a very competitive and even preferable solution to traditional methods!