715 Complete Optimization

The procedure just described is sufficient for performing an optimization based on a single type of generation equipment without accounting for any other inputs. To be truly optimal, however, the algorithm should account for any different capacities of generators installed, any utility incentives, and the variable operation and maintenance costs experienced during operation. The structure and calculation methods used for the electricity and gas utility rate schedules must be known. The optimization routine must also be able to keep track of all data acquired during a given billing period and provide cost estimates for the current hour. Any utility-sponsored incentives and rebates should be tallied along with the method of their application (e.g., by kWh produced, kW installed, etc.)

At each hour of the billing period, the optimization routine determines the number of generators that should run for that hour. This requires a prediction of the building load data for that hour, including whole building kWh use, whole building Btu use, kWh used for domestic water heating, Btu used for domestic water heating, kWh used for space heating, Btu used for space heating, and kWh used for space cooling.

The electrical and thermal output from each generation device in the building must then be determined. This may require monitoring of the ambient temperature, wind speed, and insolation.

One then must examine the benefit of operating each generator, accounting for any generators that may already be operating and for any part-load ratio (PLR) characteristics of generators that are not operating at full load. The cost function in the analysis includes all of the costs of providing on-site electrical and thermal energy. This cost is compared with that for grid consumption, and the lower of the two is chosen. To properly assess these costs, the grid electricity consumption kWhGRID is adjusted by the decrease of grid electricity consumption due to on-site power generation:

kWhGRD = kWhBLDG - kWhGEN - kWhcoOL

where kWhBLDG is the building electrical load and kWhGEN is the amount of electricity produced from on-site generators. The term kWhCOOL is non-zero if the generator provides direct cooling through absorption cooling and must be corrected for the nominal efficiency of the conventional cooling equipment:


Renewable Energy 101

Renewable Energy 101

Renewable energy is energy that is generated from sunlight, rain, tides, geothermal heat and wind. These sources are naturally and constantly replenished, which is why they are deemed as renewable. The usage of renewable energy sources is very important when considering the sustainability of the existing energy usage of the world. While there is currently an abundance of non-renewable energy sources, such as nuclear fuels, these energy sources are depleting. In addition to being a non-renewable supply, the non-renewable energy sources release emissions into the air, which has an adverse effect on the environment.

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