Energy well spent

Energy well spent

EnergyWellSpent_5aAlthough it is impossible to arrive at a single figure, one can safely say that energy is a major input cost for the fruit export industry. It is also the cornerstone of the cold chain. The combination of keeping costs down and production up is reason enough to invest energy into energy efficiency.

IN 2008, South Africans were shocked into a new appreciation of electricity. For the first time we could remember, load shedding was a part of our lives. As the national electricity utility struggled to keep the lights on, both households and industry had a taste of life without power.

Although load shedding did not cause significant fruit losses, the export industry wisely decided to heed the warning. Further motivated by substantial electricity tariff increases and global pressure to reduce the industry’s carbon footprint, an energy benchmarking project was launched under PHI-1 in 2008.

EnergyWellSpent_6aThe aim was to develop and implement a benchmarking system for energy consumption on farms and at pack houses and cold stores to improve electricity and fuel efficiency. Koos Bouwer, from KBC Industrial Engineers, was appointed to oversee and coordinate the project.

“The benchmarking results showed that it was virtually impossible to make generalisations about energy use in the industry,” says Koos. Not only did the different facilities’ energy use vary widely, they also paid vastly different tariffs – from less than R0.40 per kilowatt hour (kWh) to more than R1.40 per kWh. The best performing pack houses used around 15kWh of electricity per ton of fruit packed, while others used three times as much.

It was also clear that the different methods of cold storage had different energy implications. Storage of apples in a controlled atmosphere was extremely efficient at less than 1kWh per ton of fruit per day, whereas fruit packed in cartons on pallets used almost 8kWh of electricity per ton per day. “The important conclusion drawn from these varying results was that there were many opportunities for energy efficiency improvements,” says Koos. “If one pack house could be more efficient, there was no reason why others couldn’t.”EnergyWellSpent_1a

FROM “WHERE ARE WE” TO “WHAT CAN BE DONE”

EnergyWellSpent_3aIn 2012, the United Nations Industrial Development Organisation (UNIDO) approached the South African government to take part in its Industrial Energy Efficiency (IEE) improvement project. Funded by the Swiss Secretariat for Economic Affairs and the UK Department for International Development, the local IEE project is hosted by the South African National Cleaner Production Centre (NCPC-SA) at the CSIR. The IEE project focuses on five industry sectors, including agro-processing. Under the project’s auspices, the NCPC-SA agreed with PHI-2 to conduct fully subsidised energy audits at interested pack houses and cold stores in the fresh fruit industry. The coordination task was again entrusted to Koos. “The process we followed was more an assessment than an audit,” says Koos. “Instead of looking at how facilities adhered to standards and specifications, the consultants assessed energy use and trends.” The difference between audit and assessment is also clear from the stated purposes of the project:

  • Assist to quantify energy consumption at a facility and identify the significant energy users.
  • Identify opportunities for the reduction and more efficient use of energy in the plant as part of an energy management plan.

The energy efficiency audits initiative was rolled out in January 2012 when Koos embarked on a campaign to raise awareness in the industry. He arranged several regional workshops where NCPC-SA representatives explained the nature and process of the project and recruited participants. Companies that wanted to participate signed a memorandum of agreement with the NCPC-SA. A total of 29 pack houses and cold stores agreed to take part. The NCPC-SA assigned trained energy consultants to spend three to four days at each of the participating facilities. The audit was fully subsidised by the NCPCSA. All the participants had to contribute was their cooperation. Once the audits were completed, the energy consultants discussed their detailed reports with the owners of each individual pack house and cold store. The reports highlighted, among others, savings options, results on feasibility, quantification of behavioural changes and the expected payback periods for energy saving investments.EnergyWellSpent_2a

THE FINDINGS

The 29 participating facilities had a combined energy use of 101.1 megawatt hours (MWh) of electricity at a cost of R77 million for the year 2011. The energy audits revealed that they could save a combined 27MWh per year, putting R20.7 million back into their collective pocket. This 26.8% saving would require an investment of R26 million that will, on average, pay for itself in only 1.26 years. The potential electricity saving equals a reduction in CO2 emissions of 27 000 tons per year.  Some of the areas in which considerable efficiencies can be gained are energy efficient lighting, variable speed drives and energy management systems. The single biggest opportunity, however, is to improve the efficiency of cooling equipment.

THE WAY FORWARD

Koos points out that it is important to understand that the facilities are all unique and that the same change will have different impacts at different facilities. “It is literally impossible to generalise because one size does not fit all. The only way to improve facilities’ energy efficiency is to use individual energy audits or assessments as the starting point.” A number of the facilities who took part in the audits are doing just that. Using their site-specific recommendations, they have started to implement the suggested energy efficiency measures and are reaping the benefits. “The project seems to have acted as a catalyst,” says Koos. “It made the saving opportunities visible and facility owners are acting on it.”

© Koos Bouwer Consulting 2014

Apple packhouse

Background

The client is a large apple packhouse operation in the Western Cape where apples are stored, sorted and packed for the export market.   Due to confidentiality purposes the name of the client cannot be revealed.

The main energy source is electricity obtained from Eskom.  Apples are harvested by farmers during February to April and then stored in controlled atmosphere cold stores for up to 10 months at the packhouse facility.  Short term storage is done with regulated atmosphere cold stores and forced air cooling for packed pallets.  The cold storage and packing operations continues throughout the year.

The Issue

A previous energy audit was done at this client during 2010.  One of the recommendations was to implement an energy information model for better energy management.  This model was implemented and maintained during 2012 and 2013.  The client requested a second energy audit during 2013 to assist with the development of a detailed action plan.

Energy Audit Methodology

Information gathered in the energy model was analyzed to obtain a better view on the electricity consumption patterns in the facility.  The assessment was done for the electricity consumption period from January 2012 to December 2012.  During this period almost 7.1GWh of electricity was used at a cost of R4.59m, an average unit cost of R0.67/kWh.  The electricity balance (see below) shows that 89% of the electricity is consumed in cold storage operations.  The client agreed that this significant energy user should be the focus point of the improvement action plan.

Apple_Pie

A checklist was compiled from literature on best practices for energy efficiency in refrigeration applications.  This checklist was followed as a guideline to evaluate all the cold storage operations at this packhouse as an input towards developing the improvement action plan.

Major Findings

The major findings of this energy audit are twofold:

  1. Technical improvements can be made to improve the energy efficiency of the facility. These steps are summarized in the table below.
  2. It was clear that there was a lack of energy management skills at the packhouse. The energy information was gathered in the model, but nobody really attended to the information and acted upon it. The audit also indicated that some of the information was not correctly captured, which may lead to false conclusions.  The technical people were found to be very competent in running the cold stores, but during their busy season they do not have time for energy management activities.

Proposed Action Plan

The proposed technical action plan is summarized in the table below.  These actions would require an investment of R390 000 and will lead to an energy saving of R1.35m per year.  The projected saving of 1.84GWh per year is a saving of 26% on the electricity consumption of the packhouse facility.

apple_table

A good energy management approach is essential for sustainable energy improvement.  The packhouse has implemented sub metering and an energy information model to assist in energy management. The information should provide a baseline against which performance improvement can be measured.  The following improvements to this approach were recommended:

  • Determine the roles and responsibilities for energy management at Valley.
  • Revise the data for 2012 and establish a baseline.
  • Revise the data for 2013 and determine improvement against the baseline.
  • Set improvement targets for 2014 and beyond.
  • Continue with short interval control during 2014 based on weekly results.
  • Allocate resources for the energy management actions or subcontract.

A solar PV analysis was done for the packhouse.  A 741kWp system is recommended before excess power is fed back into the grid.  This system will cover 5200 square meters of existing roofing space. The total investment cost is R9,6m after tax rebates.  The costs of the proposed solar PV system equates to effectively paying only 34.7 cents/kWh over the next 25 years.  The projected average cost of electricity obtained from Eskom is R2.66 /kWh over the next 25 years.

Actions taken by the Packhouse:

  1. The outcome of the energy audit was received with great appreciation by the packhouse. The action items requiring capital investment were put on the budget for next year.
  2. The packhouse is also negotiating with an outside energy consultant to assist with the energy management process during next year. This will include the energy projects for improved refrigeration control.