Cristopia News Modele


CRISTOPIA NEWS

The Newsletter of Cristopia Energy Systems	Number : 18	Date: July 2001

Reduction of CO₂ Emissions with CRISTOPIA's STL

The STL is an efficient technology to reduce the CO₂ emissions by shifting the electrical consumption from day to night (when the power plant has its highest efficiency and rejects less CO₂) and by increasing the efficiency of any A/C or refrigeration system.

We provide below some typical figures for the emissions of CO₂ during the day (outside the peak period) depending on the generation technology:

Coal power plant: 1 kg of CO₂ per kWh_elec
Gas turbine: 0.3 kg of CO₂ per kWh_elec
Hydroelectric power plant: 0.005 kg of CO₂ per kWh_elec

For a given technology, the emissions of CO₂ are much lower during the night. For example, a gas turbine rejects :

0.25 kg of CO₂ per kWh_elec during the night
0.30 kg of CO₂ per kWh_elec during the day
0.40 kg of CO₂ per kWh_elec during peak hours

The gas turbines are generally used to supply the peak demand. Therefore, 1 kWh_elec of electricity shifted from peak period to night saves 0.165 kg of CO₂ (taking into account 10% of loss in the distribution). The example below shows the reduction of CO₂ emissions due to the STL.

*Case study 1*	Traditional A/C System	A/C System with an STL
Peak demand	500 kW
Daily energy consumption	3760 kWh
A/C period	10 hours: 9:00 to 19:00
Chiller	500 kW	250 kW
STL	-	STL - AC.00- 23
Energy shifted by the STL	-	1290 kWh
Energy shifted by the STL during peak hours (5 hours)	-	850 kWh
Daily electrical consumption shifted by the STL from peak hours to night (assuming a COP of 3)	-	850/3 = 283 kWh_elec
Savings on CO₂ emissions per day (0.165 kg per kWh_elec)	-	283 * 0.165 ~ 47 kg
Savings of CO₂ emissions per year (6 months of A/C)	-	47 * 6 * 30 = 8 460 kg per year
Saving of CO₂ per year and per m3 of STL	-	~ 368 kg / m³ year

This saving of CO₂ is much higher if a coal powered plant is considered.

In conclusion, the STL is an efficient technology for reducing the CO₂ emissions by just shifting electrical consumption. We will see next time the effect of improving the efficiency of the system on the reduction of CO₂ emissions.

Cristopia Energy Systems : 78, chemin du Moulin de la Clue - Quartier Cayrègues - 06140 Vence - France
Tel : 33 (0) 4 93 58 4000 - Fax : 33 (0) 4 93 24 29 38