How to Achieve Energy Efficiency in Existing Facilities
With energy costs on the rise, many industrial facilities are looking for ways to save energy and make more with less. Energy efficiency assessment teams are often composed of energy efficiency consultants, energy engineers, process engineers, simulation and modeling engineers, and plant senior process and utilities engineers. This article will provide an overview of the steps necessary to achieve energy efficiency in an existing facility.
Problem Statement
Given an industrial facility, the goal is to define targets for energy utility systems, minimize energy consumption, and find a list of possible operational and design modifications to achieve desired target(s) with minimum disruption to the production facility.
Problem Formulation
This problem can be formulated as a bi-level programming problem, where the two objectives are minimizing energy utility and minimizing energy deficiency supply. The outer problem of minimizing energy consumption should be solved at the best case scenario of the inner problem, which is minimizing energy deficiency.
Solution Approach
Rather than using mathematical programming/optimization techniques, which can be time consuming and difficult to solve globally, the plant’s energy utility needs will be defined with reasonable levels of flexibility. The energy utility systems (electricity, fuel, steam, etc.) will then be scrutinized one by one to find the near-optimal consumption of such utilities that guarantees minimum deficiency in the utility supply to plant processes.
Methodology
In order to achieve energy efficiency in an existing facility, there are four essential tasks:
- Data Gathering, Models and Targets
- Insights, Opportunities and Estimated Savings Potential
- Screen and Formulate Strategy
- Document, Report and Present
These tasks are normally exhibited in the 10-Steps procedures detailed below:
- Site Survey: Conduct a survey through templates, checklists, and interviews with process owners/proponents to gather enough data to understand the goals and constraints of the facility.
- Define Criteria: Define criteria for focusing on potential areas of interest.
- Develop Models: Create energy/utility nominal design/normal operation models with the appropriate level of detail in high level generic “path” diagrams for power, fuel, H2, steam, water, nitrogen, and air.
- Increase Detail: Add more depth to the level of detail of the energy utility model for each energy consumption “elephant” and/or other criteria of focus.
- Define Disturbances and Uncertainty: Define the effect of disturbances and uncertainty on the energy utility system models.
- Target: Identify main processing issues that affect utility utilization, link utility-utility interactions, and integrate and qualitatively optimize site utilities.
- Integrate Core Processes: Integrate core processes among themselves and with utilities.
- Generate Initiatives List: Develop a comprehensive initiatives list via identifying and estimating energy utility savings opportunities.
- Screen and Prioritize: Screen and prioritize initiatives and write a project sheet for each initiative, including a description of the opportunity and energy utility savings estimate.
- Report and Present: Develop strategies for realizing savings from facility goals, analyze the results, and report and present the results.
Conclusion
Achieving energy efficiency in an existing facility requires a comprehensive approach consisting of data gathering, models and targets, insights, opportunities and estimated savings potential, screening and formulating strategies, and documenting, reporting and presenting results. By following the 10-Steps process outlined above, industrial facilities can make more with less, save energy, and reduce their environmental footprint.