Energy Assessment on fruit & vegetable farm

Fruit and Vegetable Farm

Background

The client is a large farming operation in the Eastern Cape where citrus fruit and vegetables are produced.   Due to confidentiality purposes the name of the client cannot be revealed.

Energy sources used for the farming operations include electricity for irrigation pumping systems and housing, and diesel fuel for farming equipment, such as tractors and trucks, for the transport of produce.

The Issue

The client had grown its farming operations very rapidly over the past 5 years by using a very scientific farming approach.  New farms were developed and pumping stations were built at very remote locations. The steep increases of electricity costs during recent years and the responsibility towards greenhouse gas emissions were the main reasons for the owners to request an energy audit.

Energy Audit Methodology

Electricity is supplied at 19 Eskom points.  A cost analysis was done to determine whether the most suitable tariff structures were being used.  The costs were benchmarked against a sample of similar supply points to determine cost saving opportunities.

The electricity consumption was analyzed and split into major consumption groups, as given in the graph below.   It shows that 82% of the electricity was used for irrigation pumping systems – the most significant energy user.

Farm_Pie

The electricity consumption was split between citrus and vegetables and benchmarked against other similar farming operations.  The fuel consumption was also benchmarked against other citrus producers.  The fuel storage and supply procedures were audited to assure that all fuel purchases were accounted for and that control procedures were in place.  Maintenance procedures of the equipment using fuel were also audited.

Major Findings

The energy analysis was done for the period March 2012 to February 2013.  A total of 1,173,213 kWh of electricity was used at a cost of R1,25m.  During the same period 302,118 litres of diesel was used at a cost of R2,9m.

The control procedures for fuel were found to be very good.  The benchmarking results show that the electricity use was higher than the average of the sample of farms that was used for comparison.  The rest of the findings are explained in the summary of the action plan below.

Proposed Action Plan

  • Pumps
    • Optimize on pumping curve
    • Plotting values for each block
    • Take action where necessary
  • Housing, Offices, Stores, Packhouses
    • Replace lights with efficient alternatives when due
    • Install solar water geysers
  • Fuel
    • Consider packhouse at Addo to reduce logistic distance
  • Electricity Cost
    • Reduce Peak time on Ruraflex (pumps, timer for cold store)
    • Change large points to Ruraflex
    • Investigate Landrate cost/kWh exceptions
    • Combine small Landrate points
  • Renewable Energy
    • Measure benefits of the Solar and Wind solution at SR561
    • Consider Solar PV solutions for Badlands, Loftus or Falcon Gat
  • Energy Management
    • Centralize energy management (“Energy Manager”)
    • Improve Energy Information System
      • Update monthly for early warning
      • Review annually for updated action plan
    • Sub metering
      • Isolate houses, pumps, cold store and other facilities
    • Determine Energy Performance Indicators (EnPI)
    • Measure Improvement against baseline
    • Follow principles of ISO50001

 Actions taken by the Farm:

  1. A pumping system optimization exercise was done as a follow-up audit by using a portable flow meter and comparing results on the pumping curves and the PSAT optimisation software. A sample of 18 pumping systems was evaluated out of the total of 39 pumps.  The efficiency ratings of the pumps were found to be from 39% to 78% with the average around 60%. Recommendations were made to improve the efficiency by altering the application sizes, changing pumping impellors or installing VSD’s.  The changes will increase the total efficiency rating to 80% and save R200 000 in electricity cost per year.  The investment cost is estimated to be R90 000.
  2. The client changed one electricity point to a Ruraflex tariff structure which will save 15% of electricity cost with no investment costs. Other cost saving initiatives are still being investigated.
  3. A solar PV analysis was done for the client at one of the locations. Over the next 25 years the PV solar will cost an equivalent of 42c/kWh, compared to the current Eskom fee of R1.05/kWh and still rising each year. This would, however, require a high capital investment and the client is still evaluating the funding options.
  4. An energy management information model was developed and implemented at a cost of R25 000. This model will absorb the electricity and fuel consumption and cost, the production of crops and the rainfall variables and provide reports on the energy performance of the business on a monthly basis. This information can then be used to revise the action plan, motivate improvements and monitor the future energy performance against the 2012 baseline.

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