Description of the Project - Energy Audit of a Mining Company

You have been engaged as an external consultant by an Australian-based mining company, Rocky Mines, to undertake a detailed energy audit of its mine site in Western Australia and make recommendations on how it could reduce its energy consumption and cost. The core business of the Rocky Mines site in Western Australia is the extraction, processing and transportation of non-ferrous metals. The company operates a quarry, mineral processing and ship loading facility.

During your preliminary information gathering, you make a visit to the company and are given a familiarisation tour of the company's facilities by the Site Manager. You are also briefed by the Site Manager about the types of activities that take place in different sections of the company and some changes that have taken place over the last couple of years.

Your notes from the briefing with the Site Manager state the following:

- Many of the company's vehicles, in particular the mining trucks, run on diesel, with an energy content of 38.4 MJ per litre.
- The process heat in the mine is supplied by a natural gas boiler.
- LPG is used for industrial hot water systems and workforce amenities, with an energy content of 26.1 MJ per litre
- The largest share of energy used by Rocky Mines is electricity, sourced from the interconnected grid.
- From the beginning of 2017, a new supervisor was appointed to oversee the mineral processing section of the company.
- Most parts of the site are shut down for two weeks in December and January.

Part A. Preliminary Analysis

In your preliminary analysis, provide answers to the following questions:

1. Create pie charts for the energy cost and energy consumption data shown in Tables 1 and

2. Using the pie charts, answer the following questions:
a. Which areas of the company's operations have the potential to achieve the greatest savings and why?
b. Describe the procedure you would use to identify strategies for energy savings for the company. (Your answer should be around 1 page with single-line spacing i.e. roughly 400 words).
2. Using the data in Table 3, calculate the monthly average daily energy consumption and plot this using a column graph. Are there any trends and anomalies in the data that you would seek to explain? Suggest possible reasons for the month to month variations in electricity consumption within the years and between the years.

3. Using Table 4, plot gas consumption versus tonnes of ore processed using an X-Y scatter plot. Fit a line through your plot. What do the intercept and the slope of the graph represent? Why is the intercept not equal to zero?

Part B. Detailed Analysis

Rocky Mines wants to investigate the feasibility of supplying part of the process heat, which is currently supplied by natural gas boiler, with a cogeneration plant to reduce the total energy cost and greenhouse gas emissions. A cogeneration system produces both heat and electricity in one process as shown in Figure 1 attached. The electricity produced can be used to offset part of the electricity that would otherwise be sourced from the grid. The management has decided to conduct a pilot study on one of its industrial plant buildings with a yearly heat demand of 926,600 kWh.Energy Consumption Calculations

1. Using the electrical power output to heat power output ratio, and the heat output of the µT- CHP, determine the electrical power capacity, Ec of the µT-CHP.

2. If the µT-CHP runs at full load when operating, what is the annual amount of electricity it will produce? What is the annual amount of heat it will produce?

3. How much heat will remain to be produced by the boiler?

4. Using the electrical power output to fuel power input ratio, and the electrical power capacity of the µT-CHP , calculate the fuel power input of the µT-CHP in kW?

5. How much fuel energy (in kWh) is needed to run the µT-CHP for a whole year?

Economic Analysis

6. Calculate the yearly capital cost of the µT-CHP assuming a life time of 20 years and discount rate of 5.25%, using the annuity formula, which converts capital cost, C into an equivalent annual payment, A using a Capital Recovery Factor, CRF. Ignore the effects of inflation.

7. Determine the yearly profit of the µT-CHP by completing the table attached.

8. Assuming the consumption-bound costs, operation-bound costs and cost savings are constant over the lifetime of the µT-CHP, calculate the Net Present Value and the Simple Payback Period for the project. List any other assumptions you have made.

Conclusion

9. Based on your work, comment on the option of installing a µT-CHP at the mine site to provide part of the heating load and offset electricity consumption from the grid. Do you support the previous consultant in their recommendation that the company should purchase a µT-CHP?

Part C. Energy Mass Balance

The management of Rocky Mines would like to run some of the company's trucks on biofuel as part of the company's new greenhouse gas saving initiatives and commitment to protecting the environment. The Environmental Officer for the company has reported that a certain organic crop grows naturally on 1000 hectares of the company's land which will not be mined, and has proposed to senior management that the company produce the biofuel onsite at a location approximately 8 km from the crop fields. Senior management, however, are concerned about the energy needs for the biofuel production process as well as the waste that would be generated.

What factors have been ignored in this assessment of land requirements? Are these factors likely to be important?

Attachment:- Energy Audit of a Mining Company.rar