Research on the Integration of a Natural Gas-Distributed Energy System into the Oilfield Facility in China
Round 1
Reviewer 1 Report
The manuscript presents different energy system configurations to make an oilfield facility grid-independent in satisfying its electrical and thermal demands.
The topic is of scientific interest and the manuscript is well written. However, some improvements and clarifications are needed before it can be accepted for publication. In particular, the authors are asked to address the following issues/comments:
1) It is not clear from the literature review if there are previous works dealing with the development of distributed energy systems in oilfield facilities with the goal to make them grid independent. If yes, the authors should emphasize what is new in their work with respect to those previous works.
2) In the energy balance in Eq. (9) E_grid is missing.
3) More appealing names than “energy supply method 1 and 2” should be given to the energy system configurations. They should clearly highlight that method 1 follows the electrical load whereas method 2 the thermal load.
4) Structure of the paper: I suggest moving the information given in Section 3.1 (demand profiles, fundamental data) to the “Method” Section (e.g., to Section 2.1) in order to include in Section 3 only the results of the work.
5) The calculation procedure of “hourly average electrical load” and of “hourly average heating load” should be made explicit with the aid of equations.
6) The authors should clearly explain how the size of the gas engines has been determined for the different methods. Moreover, the reviewer’s feeling is that the power generation efficiencies of the engines used in methods 2 and 2-restricted are too high. Please provide references for these values.
7) A crucial point is the evaluation of the economic viability of each energy system configuration. In particular, the authors evaluated only the operating costs. However, a complete analysis should include also the design costs of the systems, i.e., the investment costs. Why haven’t they been considered?
8) Lines 251-252: I think that carbon emissions units are gCO2/kWh and not gCO2/m3.
Author Response
Response to Reviewer 1 Comments
Point 1: It is not clear from the literature review if there are previous works dealing with the development of distributed energy systems in oilfield facilities with the goal to make them grid independent. If yes, the authors should emphasize what is new in their work with respect to those previous works.
Response 1: Previous studies have mainly focused on the heating load of the oilfield facility, with the use of heat pumps and high-efficiency gas boilers for energy efficiency
Point 2: In the energy balance in Eq. (9) E_grid is missing
Response 2: Egrid is not included in Eq. (9) because the external grid is used as a backup.
Point 3: More appealing names than “energy supply method 1 and 2” should be given to the energy system configurations. They should clearly highlight that method 1 follows the electrical load whereas method 2 the thermal load.
Response 3: We have revised the manuscript accordingly
Point 4: Structure of the paper: I suggest moving the information given in Section 3.1 (demand profiles, fundamental data) to the “Method” Section (e.g., to Section 2.1) in order to include in Section 3 only the results of the work.
Response 4: The electric load and heating load profiles of the oilfield facility are also the results of this paper
Point 5: The calculation procedure of “hourly average electrical load” and of “hourly average heating load” should be made explicit with the aid of equations.
Response 5: We have revised the manuscript accordingly
Point 6: The authors should clearly explain how the size of the gas engines has been determined for the different methods. Moreover, the reviewer’s feeling is that the power generation efficiencies of the engines used in methods 2 and 2-restricted are too high. Please provide references for these values.
Response 6: As we have explained in Sections 2.2, the external grid is used as a backup and the natural gas boilers is used as a supplementary heating source under the FEL mode. Thus, the output (or the size) of the gas engine equals to the electrical load. As shown in Fig.4, the oilfield facility's maximum and minimum electrical loads are 939 kW and 700 kW. Besides, the efficiency of the gas engine decreases severely and cannot be appropriately operated below a 50% loading rate. Therefore, the gas engine described in Table 4 is determined for the FEL mode.
We defined the size of the gas engines for the FHL and FHL-restricted modes in the same way.
The power generation efficiencies of the engines used in this paper are obtained from the Jenbacher Technical Manuals
Point 7: A crucial point is the evaluation of the economic viability of each energy system configuration. In particular, the authors evaluated only the operating costs. However, a complete analysis should include also the design costs of the systems, i.e., the investment costs. Why haven’t they been considered?
Response 7: According to the investigation of actual natural gas distributed energy projects, the investment costs range from 2000 to 3000 RMB/kW. Investment costs significantly affect the internal rate of return and payback period of the projects. Additionally, overhaul cycles and maintenance costs vary dramatically across natural gas distributed energy projects. Therefore, the authors evaluated only the operating costs.
Point 8: Lines 251-252: I think that carbon emissions units are gCO2/kWh and not gCO2/m3
Response 8: We have revised the manuscript accordingly
Reviewer 2 Report
This paper proposes a natural gas distributed energy saving system in the oilfield facility. However, some descriptions are not clear. Some revisions are necessary in the manuscript.
1. Please indicate whether the objective function and constraints of the article are fully explained.
2. Please explain the relationship between the multiple objective functions designed in the article.
3. Please explain whether the three scenarios described in Sections 2.1-2.3 are parallel.
4. Please explain the specific method proposed in the article and how to solve the problem constructed in the article.
5. In the paper, authors have focused on energy-saving system which can supply electricity and 98 heating simultaneously through the cascade utilization of natural gas resources. Multi-energy interactive impact needs to be analyzed to indicate advantages of your work, which can refer to：
[a] IEEE Trans. Ind. Inf. vol. 18, no. 2, pp. 835-846, 2022
[b] IEEE Trans. Power Systems, vol. 37, no. 5, pp. 4067-4077, 2022
[c] IEEE Trans. Power Systems, vol. 37, no. 5, pp. 3614-3629, 2022
[d] IEEE Transactions on Sustainable Energy, vol. 5, no. 3, pp. 823-833, 2014
Author Response
Response to Reviewer 2 Comments
Point 1: Please indicate whether the objective function and constraints of the article are fully explained.
Response 1: The objective function and constraints of the article have been fully explained the “Methodology” Section
Point 2: Please explain the relationship between the multiple objective functions designed in the article.
Response 2: The operational carbon emissions and the operating cost are used as evaluation criteria in this study. The gas consumption and purchased electricity from the grid are calculated according to the energy balance of the oilfield facility. The operational carbon emissions are calculated based on different carbon emission factors and the operating costs are calculated based on different energy prices.
Point 3: Please explain whether the three scenarios described in Sections 2.1-2.3 are parallel.
Response 3: The three scenarios are not parallel. Sections 2.1 describes the status of energy consumption of the oilfield facility. Sections 2.2 designs the natural gas distributed energy system under FEL (following the electric load) mode. Sections 2.2 illustrates the natural gas distributed energy system under FHL (following the heating load) mode.
Point 4: Please explain the specific method proposed in the article and how to solve the problem constructed in the article.
Response 4: The oilfield facility provides a sufficient supply of self-produced natural gas and has an obvious price advantage. Therefore, in this study, we propose to build a natural gas-distributed energy-saving system in the oilfield facility, which can supply electricity and heating simultaneously through the cascade utilization of natural gas resources. The operational carbon emissions and the operating cost are used as evaluation criteria. Three energy supply methods of the natural gas-distributed energy system are studied. Meanwhile, the impacts of China's distributed energy policy are also quantified to determine the capacity of the power generation units.
Point 5: 5. In the paper, authors have focused on energy-saving system which can supply electricity and 98 heating simultaneously through the cascade utilization of natural gas resources. Multi-energy interactive impact needs to be analyzed to indicate advantages of your work, which can refer to：
[a] IEEE Trans. Ind. Inf. vol. 18, no. 2, pp. 835-846, 2022
[b] IEEE Trans. Power Systems, vol. 37, no. 5, pp. 4067-4077, 2022
[c] IEEE Trans. Power Systems, vol. 37, no. 5, pp. 3614-3629, 2022
[d] IEEE Transactions on Sustainable Energy, vol. 5, no. 3, pp. 823-833, 2014
Response 5: Thanks for your suggestions. Unfortunately, we are thermal power engineers, not electrical and electronics engineers, and cannot analyze the control strategies or the energy transactions of the integrated energy systems.
Round 2
Reviewer 1 Report
The authors clarified the unclear points and provided solid arguments to the reviewer’s concerns. The manuscript can be accepted for publication in the present form.
