Step 6 Refinements to Selected Project Measures

Commonly, more than one type of system or system configuration and control strategy are considered in an effort to develop the most effective option for a given application. Each option must be modeled and then compared with the baseline. Once these savings are compared with the budget cost estimates for each option, the most appropriate option will be selected and proposed. Finally, as discussed above, measure impact must be determined on a system-specific basis, as well as on an interactive facility-wide basis.

Capacity factor and reliability of actual system operation must also be considered. Capacity or load factor is a term used to express average load as a percentage of full load in a given period. For example, if a system operates at full load for 360 hours in a month that has a total of 720 hours, the capacity factor is 50%. The efficient utilization of many systems rests largely on the capacity factor of the plant. Generally, the more hours the unit is able to run, the better the project economics. This is significantly affected by competing utility rate structures. Alternatively, the profitability of a peak shaving application depends more on strategic operation over relatively few hours. In this case, reliability is a critical factor because the system must operate consistently in peak electric demand periods in order to produce expected savings.

When evaluating project economics, unplanned forced outages and other planned outages will be considered. When planning for and evaluating a project, one must therefore consider the expected capacity factor of the plant and the reliability of the proposed system. This includes projecting savings based on less than optimum performance, or incorporating the cost of mitigation measures such as standby capacity.

Another part of energy system analysis for the facility will be to identify the reliability and redundancy requirements. This pertains not only to central systems, but also to auxiliary components such as pumps and fans. Having an extra engine on standby but only one fuel pump for both engines is an example of a vulnerability to interruption that is sometimes overlooked. If the fuel pump fails, neither engine will function. Hence, well conceived, redundancy considerations should figure largely in the equipment selection process inclusive of system auxiliary components. Installation of equipment redundancy allows for more creative operating strategies. However, it also increases project capital cost, so the benefits must be identified and carefully considered. If the intent of redundancy is exclusively to protect savings, it may not be valued as highly as if it is to meet mission critical requirements as well.

An important aspect of measure refinement is the assurance that the system output is compatible with the load requirements. Heat recovery systems are particularly sensitive to this, as discussed in the Savings Analysis step. When considering use of recovered heat, it is important to identify the thermal levels (temperature) of energy that can be produced (e.g., hot water or steam) and the amount of heat available at the required temperature. It is also important to consider any modifications that can be made to existing systems to allow them to use recovered energy in the form that it is available. For example, if recovered heat is to be used to serve a process that currently uses steam, either the recovered heat must be available as steam, or the recovered heat can be made available as hot water and the process converted to operate with hot water. Processes can also be converted to operate at lower temperatures. By serving a lower temperature process, the efficiency of the heat recovery process can often be increased.

The potential for conversion of process requirements becomes an important part of potential measure refinement. As part of the feasibility analysis, various options should be considered for improving the balance between summer and winter thermal loads. Where applicable, it may be economical to increase thermal loads through added baseload applications. The application of steam turbine-driven or absorption chillers as discussed above are two of several options.

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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