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Potential of wine and pumped storage for energy security

Only some of the detailed opportunities are highlighted in this paper. Further details can be found in the complete guideline Centre for Renewable and Sustainable Energy Studies, 2014. As an example, at one winery, the option was identified to have separate chilled water tanks. During the off-season, when the demand drops, it is possible to use one smaller tank, which will reduce the energy demand.

The winery uses a 70 000 litre tank. By reducing the storage size by half, a 135 kWh cooling reduction is achieved, which equates to a saving of R130 950 per annum; for its specific tariff structure.

Another potential opportunity for performance improvement of the chilled water system is on the control of the water temperature.

It is crucial to know the required process temperature. If the water temperature is increased, savings can be achieved. Other water improvements opportunities are: This then requires a proper, in-depth analysis and understanding of the system. The selected pump for an operation may be efficient, but in general there is wasted energy consumption.

Irrespective of the type of pump that is used for an operation, the following factors may assist in saving energy: These will ensure that the pump speed will be controlled according to the pressure needed in the system. Thus, if the cooling on all tanks is off, the motor on the pump will reduce its speed.

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A VSD will only ramp up the motor when cooling on a tank is opened, in order to supply the necessary pressure in the system to supply the tank with chilled water. However, even though the VSDs improve the efficiency of the energy system, more financial analysis will be necessary over the lifecycle of the energy system. For example, consider a circulation pump 5.

Insulating hot surfaces and cold rooms is one of the simplest and most cost-effective ways of increasing energy efficiency. The payback time for insulating a pipe is generally less than one year. For tanks, valves and fittings, immediate savings can be realised from insulating where no insulation existed. Apart from the insulation itself, housekeeping provides opportunities for costs savings. For example, damaged insulation and damaged covering and finishes were identified in a number of the cases.

Retrofitting the existing system also provides an opportunity.

  • This bag pressing operation is a high volume low pressure application, whereas a compressor delivers high pressure low volume;
  • Retrofitting the existing system also provides an opportunity;
  • Winery employees play a large role in this form of cost saving, as does installing automatic lighting controls;
  • Figure 6 shows the electricity delivered by the PV system of Table 4 compared to the total electricity demand.

This can be done by upgrading the existing insulation levels or review the thickness requirements. Saving opportunities therefore exist in matching the water heated with the required temperature and amount needed: Opportunities can also be realised by adopting other systems, such as heat pumps and excess steam from the boiler.

Consider a typical 200 litre geyser with an electrical element, rated at 4 kW. Winery employees play a large role in this form of cost saving, as does installing automatic lighting controls. Harvesting daylight with the installation of skylights can be considered where heat ingress is not a problem. Savings are realised as soon as the new lights are installed.

The most efficient lighting sources that are commercial may last longer than the existing less-efficient lighting, which justifies the capital expenditure. Special care needs to be taken when deciding and selecting efficient lighting sources.

They need to comply with Occupation Health and Safety Act requirements concerning light-intensity levels in the workplace.

  • The government looks forward to working closely with the IEA as we continue to develop Australia's energy blueprint;
  • Figure 6 shows the electricity delivered by the PV system of Table 4 compared to the total electricity demand;
  • Lawrence Berkeley National Laboratory, available from:

It is critical to do the lighting design in advance to ensure that the replacements comply with the regulations. This is done in cycles, with each cycle being at a slightly higher pressure, up to a maximum of 2 bar. Consider a 20 tonne capacity press using six cycles.

Typically, for this capacity, the requirements are a flow rate of 21. Having the right operational parameters is crucial.

By increasing the storage capacity to the required capacity may result in energy savings. High blower fans can be installed to pre-fill the bags and using the compressors for the final pressure. This bag pressing operation is a high volume low pressure application, whereas a compressor delivers high pressure low volume.

Some of the bag presses do have initial filling using blowers, but this method could potentially fulfil the majority of the requirements. The exhaust air from the bags could then also be re-used by introducing it at the inlet to the proposed blower fans. The cycles of the individual presses would have to be synchronised to take maximum advantage of this, but the savings would be good, as the blower fan would only have to raise the pressure of the air by whatever was lost during the process.

Another example of the compressor optimisation was observed at one of the site visits. The compressors were situated outside in dusty conditions. This may reduce the efficiency of the compressors. Under these conditions, compressors can draw in warm air.

Also, the dusty conditions may cause clogging of air filters. As the filters are on the inlet side of the compressor, the effect is to reduce compressor performance.

This could potentially allow further savings of up to 4 000 kWh over the season. Cooler air can also be ducted from the cooler room. This equates to savings in the order of 4 500 kWh for the harvest season. Air leaks are amongst the major factors that reduce compressor performance. They can be managed by a tagging system and a maintenance plan, which would see that each leak is noted and repaired. During the harvest season, when the compressor is run continuously, cycling is not an issue.

During the rest of the year, the cycle times may need to be monitored and other ancillaries such as refrigeration dryers can be switched off with the compressors when the required pressure is achieved. Reducing the output pressure of the compressors could possibly be targeted if the capacity of the storage is large enough to allow storage at a lower pressure and still achieve the results required. Thus, reducing the pressure from 7. An illustration of the potential energy saving from the compressor is maintaining the compressor pressure at the required pressure.

For a compressor that has 2 x 75 kW capacity - a typical size that is used at a winery, that operates for five days a week and 20 weeks per year, the energy costs are expressed as follows: If the set point was reduced from 8. Figure 5 shows the measured energy efficiency improvements at one of the case study farms.

The graph shows how the energy efficiency initiatives have yielded results. When there is proper measurement in place, trends can be observed and reported for further decision-making. The main aim was to address the risks and uncertainty that are associated with the integration of renewable energy systems in the wine industry.

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The assessment considered the solar resource availability in the Western Cape Province and showed it to be adequate, indicating considerable potential for integrating solar thermal energy or photovoltaic PV technology. Solar thermal can be used to supply solar thermal process heat, or used to pre-heat boiler-heated water or to drive a chiller. PV technology could be used to generate electricity for the winery see Table 4. Except for the high electricity demand months in the winery, the PV system results in high solar share.

Figure 6 shows the electricity delivered by the PV system of Table 4 compared to the total electricity demand. The PV system is optimised for annual energy delivery, but it is possible to optimise it for the period of high energy demand. That would mean, however, that the PV system would generate excess electricity at other times, which could make business sense if the excess electricity could be sold to the grid.

To this end the National Energy Regulator of South Africa has released a discussion document of tariffs and other regulatory issues to allow grid-tied systems.

Conclusion A number of drivers have resulted in the need for a guideline for energy management for the South African wine industry. Furthermore, it shows by way of case studies from South African wineries, typical energy savings opportunities that exist. However, the energy efficiency and cost cutting initiatives can be capital intensive.

It is then advisable that the winemaker approaches the EnMS systematically. The first step would be, after identifying low hanging fruit potential savingsto engage with a service provider. This would be on a high level where the winery can pose all the relevant questions that would assist in decision-making. The key critical aspects - summarised in Table 5 -would be useful to the winemaker or operations manager in deciding whether to go ahead with a project; and thus to engage with the service provider.

Acknowledgements The authors thank Winetech for making available the research funding to undertake this work, as well as the participating five wineries. The technical contributions of Koos Bouwer and Barry Platt, in their capacity as national experts in energy management systems and systems optimisation respectively, are specifically acknowledged during the case study investigations.

The feasibility of alternative energy options. A guide to energy efficiency innovation in Australian wineries. Department of Industry, Tourism and Resources, Canberra. Winetech document, available from: Benchmarking and energy and water savings tool for the wine industry.

Lawrence Berkeley National Laboratory, available from: Energy management systems - Requirements with guidance for use. How ISO 50001- Energy management can make industrial energy efficiency standard practice. Lawrence Berkeley National Laboratory, California. Integrated benchmarking and self-assessment tool for the wine industry: Applied social research method series.