Process and energy data was collected from sub-metering ..... the Maltings sector
-specific manufacturing processes and to provide key insights relating to ...
Industrial Energy Efficiency Accelerator - Guide to the maltings sector
Around 1.5 million tonnes of malt is produced in the UK each year by seven large maltsters and seven smaller maltsters. Domestic beer and whisky production accounts for almost 90% of the output from the Malting industry, the remainder being used in a wide range of foods, with some exported. The CO2 emissions associated with the Maltings sector is approximately 340,000 tonnes of CO2 per annum.
Executive Summary This report presents the findings and recommendations of the Investigation and Solution Identification Stage of the Industrial Energy Efficiency Accelerator (IEEA) for the Maltings sector. The aims of this stage were to investigate energy use within the Maltings sector-specific manufacturing processes and to provide key insights relating to opportunities for CO2 savings. Around 1.5 million tonnes of malt is produced in the UK each year by seven large maltsters, and seven smaller maltsters. Domestic beer and whisky production accounts for almost 90% of the output from the Malting industry, the remainder is used in a wide range of foods and some is exported. The CO2 emissions associated with the Maltings sector are approximately 340,000 tonnes of CO2 per annum. Five sites were directly involved in the investigations carried out for this project. Collectively the participating sites represented about 28% of UK malt production. Process and energy data was collected from sub-metering installed at two sites. The methodology used in this study included: Site visits and discussions with host site personnel Gathering and analysing historical energy and process data from host sites Installation of energy sub-metering on two sites Collection and analysis of sub-meter data with process data Desk based research of potential energy efficiency opportunities and innovations A questionnaire to Maltsters on priorities, barriers, progress to date and their ideas A workshop to identify and address barriers to deployment of energy efficiency opportunities
Maltings Sector Guide
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Energy use within the sector 1
The Maltings sector uses some 1,375 GWh of energy each year. This is dominated by the use of fuels for process heat, with annual fuel consumption being 1,176 GWh (86% of total). The majority of the heat demand is for the kilning process, with grain drying representing the second largest heat energy use. At least 78% of the heat demand in a kiln is thought to be associated with the evaporation of water, in order to dry the malt to its final moisture content (see section 4.1). Most kilns are fitted with glass tube heat exchangers to recover some of the vaporisation energy of water (latent heat) from the „air off‟ from the kiln, to preheat the ambient air coming into the kiln. During the pre-break phase of kilning, a heat exchanger is able to recover some 20% of the energy available in the „air off‟ stream (see section 4.2). The remaining 80% of energy is lost to atmosphere as saturated water vapour. Increasing the recovery of this energy is the key opportunity for the sector. The sector fuel consumption consists of the fossil fuels natural gas, gas oil, LPG, kerosene and coal. Replacement of some of these with biomass, such as woodchip, would reduce energy costs and carbon emissions. During kilning, warm dry air is blown from below through the kiln bed, inducing both a temperature and a moisture gradient across the depth of the bed. These gradients gradually reduce as the kilning cycle progresses, as the moisture evaporates and the malt increasingly heats up. The temperature and moisture gradient throughout the bed means that there is variation within the batch in terms of the length of time that the malt is held at a given temperature. This variation necessitates the need for blending post-kilning, to ensure finished product consistency. It also represents an opportunity to improve energy efficiency (see section 4.4). The standard current practice within the industry is to control the germination and kilning processes primarily on time, air temperatures and humidity. Whilst these control methodologies enable Maltsters to consistently produce high quality malt, energy efficiency could be increased by using direct measurement of temperature and moisture content of the malt bed itself. Direct process control could allow processes to be stopped sooner once the required parameters have been met, thereby shortening the cycle time. This would result in energy savings and potentially increased throughput (see section 4.3). Load to kiln moisture refers to the moisture content of the grain at the end of the germination process. It has a direct bearing on the amount of energy used in the kiln to evaporate the water and is therefore an important driver of variation in batch energy consumption. Tighter process control and the use of statistical management methods would help to drive continuous improvement in consistency and energy efficiency (see section 4.5). Whilst extensive production information is captured within the industry, there is typically little energy use information available at the unit process level to inform management decisions and measure performance improvement. Implementation of automated Monitoring and Targeting (aM&T) systems is becoming more common within the sector, but there is scope for further roll out (see Section 5.2.6).
Carbon Saving Opportunities Significant opportunities for increased energy efficiency exist in the Maltings sector. The main opportunities include increased energy recovery, increasing the final moisture content of the malt, implementation of Combined Heat and Power (CHP) systems as well as increased uptake of Automatic Monitoring and Targeting (AMT) systems. The opportunities have been categorised into innovative and good practice opportunities. It must be noted that the opportunities are not additive. This is due to some opportunities overlapping or being mutually exclusive.
1
Climate Change Agreement data
Maltings Sector Guide
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Innovative opportunities Energy recovery from the kilning process can be improved in a variety of ways, and three alternative solutions have been outlined. The first, closed cycle heat pumps, can be used as a second stage of energy recovery after the glass tube heat exchanger. It is considered possible to retrofit these to existing kilns. Such a heat pump is considered able to recover an additional 43% of energy, for a total energy recovery of 64% in conjunction with the glass tube heat exchanger. This solution is outlined in section 5.1.1. The second solution for increased energy recovery, open cycle heat pumps, can potentially be adapted to suit the malting process. Open cycle heat pumps differ from closed cycle heat pumps in that they are able to use the water evaporated from the malt as the means to recover energy. A higher energy recovery factor can be achieved than is possible with closed cycle heat pumps. It is not considered viable to retrofit open cycle heat pumps to existing kilns, hence this solution is limited to new build kilns. Further details can be found in section 5.1.1. The third solution for increased energy recovery is to implement a dedicated energy efficient drying system to dry the malt before curing it in a traditional kiln. This solution is outlined in more detail in section 5.1.1. Another significant opportunity for Maltings sites operating hot water, steam or hot oil systems to heat their kilns is the burning of biomass instead of fossil fuels. With the addition of a suitable burner or boiler and associated fuel storage and handling equipment, those sites would benefit from the Renewable Heat Incentive (RHI) for every kWh of woodchip energy. This is discussed further in section 5.1.3. The implementation of kiln bed turning during the kilning process would reduce the humidity and temperature gradient across the depth of the malt bed. This may enable a shorter kilning cycle and hence reduce energy consumption. This is discussed further in section 5.1.5. A further opportunity to increase energy efficiency in the Maltings sector centres on the final moisture content of the finished malt, which is typically 4%. Kiln heat requirements would be reduced if the final moisture content could be increased to, for example to 6%. This opportunity requires negotiation and agreement with customers including Brewers and Distillers. Please refer to section 5.1.7 for further details on this and other supply chain collaboration opportunities. Where possible, outline business cases have been calculated for each the innovative opportunities. The level of confidence associated with these business cases is not currently sufficient for investment decisions to be based on them. Rather, the business cases are intended to highlight areas that Maltsters should pursue and investigate further. Table 1 below outlines the summary business cases for each of the innovative opportunities that we have been able to quantify. A number of these opportunities are likely to require R&D activity as well as a pilot project in order to develop sufficient confidence in their business cases to allow investment decisions to be taken. For further details, please refer to section 5.1.
Table 1 Summary of innovative opportunity business cases, sector level Opportunity
Heat pumps, closed cycle Heat pumps, open cycle Energy efficient drying Burning Maltings co-
Implementation costs (£)
Saving (£ p.a.)
Saving (t CO2 p.a.)
Cost (£/t CO2)
Payback (years)
Sites applicable (%)
£24,750,000
£4,500,000
33,000
£750
6
100%
£75,000,000
£14,650,000
115,000
£640
5
100%
£142,500,000
£10,400,000
85,000
£1,675
14
100%
£13,000,000
-£27,000,000
40,000
£320
None
100%
Maltings Sector Guide
products Burning woodchips Direct T & RH measurement Kiln bed turning Process management Supply chain collaboration
4
£21,000,000
£4,200,000
38,000
£550
5
26%
£1,130,000
£580,000
4,700
£240
2
100%
£7,500,000
£1,300,000
10,750
£700
6
67%
£55,000
£200,000
1,750
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