PRACTICAL ELECTRICAL ENERGY CONSERVATION ON INDUSTRIAL SITES: ARTICLE 4 - COMPRESSED AIR SYSTEMS

Air supplied to a cylinder/actuator on a machine.
Note the exhaust port, from which the air is lost
when the cylinder is depressurised.

Compressed air is used widely in industry for applications such as the actuation of automatic valves and slides, to power tools such as hand-held drills and grinders and also for a wide range of open-blowing applications. Various compressor designs exist, each with their own energy consumption characteristics. Depending on the size of the plant concerned and the applications to be assessed, energy consumption associated with compressed air can be daunting to analyse and optimise. There are however a few basic considerations that, if kept in mind, can help to rapidly reduce the energy usage associated with compressed air on industrial sites.

Before getting into the many different aspects regarding energy efficiency in compressed air systems, I would like to make an important point regarding the quantum of energy used for compressed air production. The energy used to produce compressed air is supplied to the induction motors driving your compressors. If you know the average power consumption of these motors (you will need to measure this with a power logger), and the running hours of your compressors, you can quite easily calculate the energy consumption (and energy costs) associated with compressed air production. This immediately allows you to prioritise energy efficiency opportunities in this area relative to other energy-consuming activities on your site.  The effort invested into analysis for a site operating a small 5.5 kW piston (also called “reciprocating”) compressor would generally be much less than for a site operating  a 90 kW oil-filled screw compressor, for example.

As with utilities such as steam, a systems view is essential when assessing compressed air systems. This means looking at the production, distribution and usage of compressed air, on the understanding that savings are achievable through improvements in efficiency in all of these areas. It is also important to appreciate that elements of the system interact with each other, and any changes made must be assessed in terms of their impact on the system. Halving your compressed air usage would have implications for the loading of your compressor, and may necessitate a re-think in terms of its operating philosophy, for example. Let’s look now at some of the individual components of a compressed air system and the types of efficiency opportunities typically presented.

Compressors

Compressors take in ambient air and increase the pressure of this air from atmospheric conditions to a level determined by the capabilities and settings of the compressor. Compressors should be located in cool, dust-free areas, to ensure that the air being compressed is as dense as possible to begin with, and to prevent clogging of the intake filters. Blocked filters operate with increased pressure drop and therefore increase the amount of energy required to produce a unit of compressed air. The drive system of your compressor should be as efficient as possible, and this entails:

• Using motors with high efficiency levels
• Using direct drives or cogged/synchronous belts wherever possible (instead of v-belts), and ensuring that these belts are aligned and tensioned correctly
• Using variable speed drives where appropriate (more on this below)

Depending on the type of compressor concerned and its duty, control systems can vary. "Start/stop”  philosophies are commonly employed on small piston compressors which are lightly loaded. Screw compressors are often operated using a “loaded/unloaded” philosophy. In some circumstances, screw compressors are operated using variable speed drives. It is necessary to understand each individual compressed air system as a whole in order to determine whether the method employed is appropriate. It is not always optimal to install a VSD on an existing screw compressor, since VSD’s in themselves incur small energy losses and both compressor efficiency and motor efficiency vary with speed. VSD’s add most value for screw compressors that are sometimes under-loaded or which supply processes with variable air demand, since the amount of energy used when “off-load” can be significant (up to 50% of the energy required when “on-load” in my experience).  Where multiple compressors are in service, significant opportunities for energy conservation are often available in the optimisation of the control schemes used to control them, and here again system considerations are paramount.

It is generally necessary to log compressors over a period of time to assess power consumption and system pressure variations. This provides necessary information on loading and also provides insights into demand (for compressed air) behaviour and the suitability of downstream equipment, particularly as regards items such as air receivers. When doing such logging, recognise that it will be necessary to note what is physically happening in the field, and to relate this back to the data acquired through logging. It is never a case of simply setting up a logger and coming back the next day to analyse compressor data. You will need to take note of which users are drawing air and at which times, allowing you to relate this back to the recorded compressor behaviour.

In terms of the air pressure delivered, it is best to operate the system at as low an average pressure as possible. Producing air at higher pressures than necessary not only wastes energy at the compressor itself, but also exacerbates losses due to leaks and “artificial” uses. A simple example of an artificial use would be air usage incurred for actuating valves, slides and other such equipment at a higher pressure than necessary. Such pistons travel over a given stroke distance, regardless of the air pressure applied. Higher pressures simply increase the speed of the stroke, but this speed may not be necessary, and because the mass of air in the cylinder volume is higher at higher pressures, losses result. A final point regarding air pressure is that energy efficiency and the minimum pressures demanded by individual processes are not the only considerations when determining the optimal pressure of the compressed air produced. System capacity is a further very important consideration. Generally, the pressure of the air produced has to be high enough to overcome line losses while still delivering the air at the pressure and rate required by users. Producing air at a further pressure premium allows a given compressed air system more capacity to respond to sudden demands. The installation of additional receiver capacity is one way to get around this, but of course this has a cost, not only in terms of capital, but also in terms of losses for systems that are regularly depressurised.

Compressor sizing has a significant impact on energy efficiency. Excess compressed air production capacity can waste a significant amount of energy in the case of screw compressors, since they will spend a lot of time off load. For piston compressors, excess capacity means increased stoppage and start-up frequencies, increasing wear and tear and power demand peaks. Where there is a large baseload air demand, consider supplying this with a screw compressor, with fluctuations above this baseline supplied through a smaller piston compressor, or through the use of appropriately sized air receivers. Many of the sites I investigate have far too much air capacity, generally because sites anticipate future increases in air demand with expansion of the site when purchasing the compressor. This is a wasteful practice.

Distribution

The most obvious energy conservation opportunity here is in reducing air leaks. These leaks are not always due to poor maintenance, but could also be a result of poor operational practices, e.g. bleed valves that are left open on air receivers to remove accumulated water and oil. The quantification of the energy losses associated with air leaks is tricky, and in most cases is an estimate. You can find various charts which correlate the size of the aperture (which is where the estimation bit comes in, since it’s often too small to measure accurately) and the air pressure to quantify the rate of air loss. This can then be correlated back to the compressor capacity and energy consumption to convert the leak to an electrical energy value in order to calculate its cost. In many systems it is possible to log the compressor to determine the extent of system air leaks – all that is required is a period during which there is zero demand for air, in which case the compressor is running only to compensate for leaks. For compressors that go on and off load, care should be taken when interpreting results however, since energy consumption profiles will be different at higher compressor loadings i.e. when there are demands for air.

From a design point of view, air distribution lines clearly need to be sized such that pressure drop is minimised as far as possible. For a given flow rate, this is a function of their length, the number of bends in the pipe work, the materials used and of course the diameter of the lines. Distribution systems need to allow for the periodic removal of water and oil, both of which affect air quality (with potentially serious consequences for product quality where air comes into contact with product) and also increase pressure drop. Of course, it is necessary to have the requisite equipment to deal with these contaminants at source, through filters, refrigerant driers and automatic bleed-off systems. Such systems will never operate at 100% efficiency, and hence the installation of additional bleed-off points throughout the distribution network is still advisable. The various fittings in a compressed air distribution system can all contribute to system pressure drop, and hence filters, driers and other equipment should be regularly serviced.

Where areas of a plant are taken out of service, it is good practice to isolate the air supply lines to these areas, since leaks can often arise and go unnoticed. It is also a good idea to install distribution lines in areas that are easy to access. This not only makes maintenance easier, it also allows for the rapid detection of air leaks. I have audited plants in which air lines are run below ground, in conduits, under equipment and also very high up. This makes leak detection nearly impossible.

Inspection of the air distribution system should be practiced regularly, and leaks should be promptly addressed. Such inspections can easily be scheduled as part of your site’s preventive maintenance programme. The point here is that air leak management is an ongoing process, rather than a one-off activity. For large plants, you may want to invest in specialist leak detection equipment such as ultrasonic detectors, which can also be used for various other condition monitoring purposes. I suggest that you address the obvious leaks first before making such an investment.

Usage of compressed air

Each process that uses compressed air should be investigated to assess whether that usage can be reduced, and if so, the potential reduction should be quantified in order to compare the benefits of reduction to any potential risks. Reduction can imply:

• Using the air for a reduced period of time;
• Using the air at a lower pressure than currently used – here regulators may be needed;
• Using the air more efficiently through modifications to equipment;
• Eliminating the use of compressed air – in this case a more-efficient alternative has to be found e.g. use of an electrical device instead of an air-powered one or use of a low-pressure blower to dry or cool product rather than a compressed air stream. In some cases air can be exchanged for another lower-cost medium, such as cooling water for example.

The usage aspects of compressed air efficiency require intimate knowledge of your processes, and cannot be left to an outsider, not even a compressed air expert. The issue here is that the consequences of overzealous actions taken in the name of energy efficiency could be out-of-specification product, rework, product recalls or even hazards to consumers. These cost far more than the compressed air savings. Hence it is best for compressed air experts and process owners to work together on this aspect of efficiency.

Inappropriate uses of compressed air should be stopped. Examples of inappropriate uses are things like open blowing to remove dust from equipment and clothing, for example. I come across many sites which have numerous air tap-off points installed across the plant exclusively for such uses. Of course it is not good enough to simply say that such uses should be stopped without providing an alternative. The reasons for their existence need to be investigated and root causes need to be eliminated for cessation to be sustainable.

The regulation of air pressure at point of use is vital to ensuring that only as much air as is needed is actually used. Note however that since there is a pressure drop across a regulator, these devices are not devoid of energy losses.Unregulated air usage can lead to significant artificial air usage, and can also lead to poor process performance in some applications. For example, air-powered spray painting machines operating with variable air pressure will produce inconsistent paint application rates. 

In summary then, assess the scale of your energy usage for compressed air production within the context of your total energy consumption to determine the level of effort required to optimise energy use in this area. Begin with simple best practices first, such as reducing system pressure, fixing leaks and reducing/eliminating inappropriate and artificial uses. Remember that as an integrated system, compressed air production, distribution and usage all interact with each other, and also interact with the processes to which the air is being supplied. Design issues such as compressor location, use of VSD’s, piping layout, receiver configuration and others will require some financial outlay to correct, where necessary. In many cases however, the costs can be justified by the efficiency gains. Proceed in an incremental manner, taking care to review system impacts as you go along.

RESOURCE EFFICIENCY IN STEAM SYSTEMS – ARTICLE 1: WHY A SYSTEMS APPROACH?

Gauges in a Boiler House 
Control Room

Steam is used as the preferred heating medium in a wide range of industries for various reasons, including its low cost, ease of handling and favourable thermodynamic properties. It may be produced using a number of different energy carriers, such as coal, natural gas, fuel oil, and other fossil fuels, as well as from renewable energy sources, such as biomass and solar energy. 

Where fossil fuels are used, efficiency gains made in steam systems ultimately translate into reductions in the amount of boiler fuel used, which has economic and environmental impacts. The optimisation of steam systems can also result in reduced water consumption, reduced effluent generation rates and also positive impacts on effluent quality.

In future posts I will examine individual aspects of steam systems and how efficiency gains can be realised, but it what I’d like to do in this article is highlight what the components of a steam system are, and why it is necessary to evaluate steam systems in an integrated way. In simple terms, steam is produced by heating treated water in a boiler, changing the phase of the water from liquid to gas. This gas (which may be saturated steam or superheated steam) is then distributed to point of use. The specific purpose for which the steam has been produced determines what happens next. The steam may be used directly, in which case it may be incorporated into products or process streams, it may be used to transfer heat to a process stream using a heat exchanger, or it could be used to drive a turbine. In the case of heating applications, the condensate may be recovered and returned to the boiler for reuse, reducing energy requirements and saving treatment chemicals. In the case of turbines, these may be of the back-pressure variety (in which the exhaust steam is at a lower pressure, but may still be used for various purposes, with or without condensate recovery) or the condensing variety, in which case the condensate may be recovered for reuse.

The major components of a steam system are:

• The boiler, which is used to generate the steam – these may be water-tube or fire-tube boilers, depending on required steam characteristics and quantities. An individual site may employ a number of boilers, and these may use different fuels.
• The distribution system, which is used to distribute the steam to points of use and comprises items such as steam headers, letdown valves (or pressure reducing stations), isolation valves, and traps.
• The individual steam users, the nature of which depends on the industry concerned – some of these users may use the steam consumptively, in which case condensate cannot be returned.
• The condensate recovery system used to capture and return condensate to the boiler – this comprises steam traps and piping along with vessels used to store the condensate before it is pumped.

General Overview of a Typical Steam System

This above is a general steam system architecture, but I need to stress that individual sites can have very different steam systems, and each site has to be evaluated on its own merits. The cost inputs to each site’s system also mean that there are no general rules in terms of the feasibility of individual steam system efficiency options. It is therefore vital that a comprehensive system model is constructed that can be used to test various assumptions regarding individual options as well as various option permutations. This latter point is very important, and here I’ll address why a systems approach is so necessary when considering resource efficiency for steam.

Systems and systems thinking are everywhere in the realm of industrial sustainability. To consider steam systems as defined in this post as self-contained would be wrong, since steam systems interact with broader process systems on industrial sites in ways that go beyond thermodynamics and heat transfer. For example, in the dairy or beverage industry, too low a steam pressure in a sterilisation unit can lead to microbial contamination of food products, with dire economic, environmental and possibly social consequences. Always bear the broader system within which steam systems operate in mind when dealing with steam. The construct of a steam system as described here (and note that this is not my concept, this is a generally accepted model, used globally by organisations like UNIDO and the US DOE) is however powerfully relevant from a resource efficiency perspective, and in the series of articles that will follow this one, the focus will be on resource efficiency. 

From this perspective, it is easy to see why a systems approach is needed, given the impacts that projects carried out in various parts of the steam system can have on the system as a whole. Here are a few simple examples:

• Condensate recovery is increased. This increases energy recovery to the boiler and reduces fuel consumption. The amount of make-up water required is reduced, as is the quantity of treatment chemicals used.
• High-pressure condensate which was previously discarded is flashed into a lower pressure steam header, reducing the amount of low-pressure steam that has to be produced by the boiler. This reduction in generation rate reduces fuel requirements. Water and chemical consumption are also reduced.
• High-pressure condensate flash from a condensate recovery tank is used to pre-heat boiler feedwater in a heat exchanger, and the condensate produced is recovered for reuse. While still positive from a system perspective, the gains are less than for the “flash-to-header” option, since the efficiency of the boiler now becomes a consideration when converting the recovered condensate into steam. Additional energy is also needed for the boiler feedwater pumps with this option.

There are many more approaches than these that are available in terms of increasing steam system efficiency. Where a basket of options is implemented, expect that they will interact with each other. For example, reducing boiler blowdown rate could hurt the viability of previous projects aimed at recovering blowdown flash, or aimed at blowdown heat recovery (or both, since these could be implemented in tandem). Radical reductions in steam consumption can lead to a boiler operating a far below its rated capacity, negatively impacting on its efficiency. Without the integrated consideration of impacts such as these, you run the risk of defeating the object of your resource efficiency projects. In future posts I will explore individual steam system optimisation opportunities and how they fit together within the context of a steam system. I will also compile a glossary of steam terms which I will make available through my company website, and I will link to that from this blog as soon as it is available. In the interim, start thinking about the individual elements of your steam system and how they relate to each other. Steam systems typically represent a sizable economic opportunity, and are worthy of detailed investigation at every industrial organisation interested in reducing emissions and energy intensity. 

THE AMAZING GREEN JOB CREATION MACHINE

If businesses, state-owned enterprises and state institutions pursued sustainability vigorously in South Africa, there is little doubt in my mind that there would be a positive impact on our unemployment problem. Of course, fixing our problems requires an integrated, multi-stakeholder approach, good governance, exceptional discipline and a host of other ingredients, and I certainly don’t claim to have all of the answers here. However, in terms of the practical application of sustainability in industry, I do have some insights, and would like to illustrate the practical power of sustainability as a force for good and as a viable route to competitiveness for organisations.

Industrial sites represent endless opportunities for increased resource efficiency. The thing is, while the use of specialist measurement tools, software applications and technical knowledge can be used to identify opportunities, to most people these opportunities remain hidden. And so we have many industrial sites that continue to operate oblivious to the potential opportunities available through investment, optimisation and simple process changes, which could significantly reduce their costs and increase their competitiveness. I see this regularly, even with respect to very large, successful and profitable companies, but of course this is also prevalent at small companies, where technical resources are scarce.  This enormous-yet-hidden goldmine of productivity improvement opportunities represents a massive job creation opportunity for our country, which has been in the grips of a deep unemployment crisis for decades now.

Measurement tools used to assess
opportunities in steam systems

To illustrate the point, consider a typical manufacturing site. This site would use inputs such as raw materials, water and energy and, using specific transformation processes, would produce products, by-products and liquid, solid and gaseous waste streams. 

Now imagine if this site embarked on a structured process to identify, develop and implement a portfolio of resource efficiency projects, each of which was aimed at reducing waste and the consumption of resources, and preventing pollution at source. Some of these projects would require simple optimisation, such as changes to a process set point e.g. operating a high-temperature process at as low a temperature as possible reduces energy requirements. Some would require simple changes in operating procedures – for example, all employees to switch off their air conditioning units when they leave their offices at the end of the day. In these two cases, you could argue that there could be some job creation potential arising from the savings derived from these actions, but there are no guarantees that this is where the savings would be diverted. We cannot therefore rely on such actions to be the engines of job growth. 

There will however certainly be a sizable number of projects which would require changes in technology, modifications to plant and equipment, specialist services such as software changes for automated facilities and other types of interventions best carried out by an outside third party. This is where I believe the serious job creation potential lies, and importantly, since most of these projects tend to be too small to attract large engineering houses, many of these jobs would be created in small businesses, now widely regarded as the primary job creators in modern economies.

To give you a feel for the types of opportunities I am referring to, I have included some examples in the table below:

RESOURCE EFFICIENCY/COST-REDUCTION  OPPORTUNITY	EXAMPLES OF POTENTIAL PROJECTS CARRIED OUT BY CONTRACTOR
Steam system modifications	Insulation of steam lines and valves, routine assessment and repairs to steam traps, installation of an in-line oxygen analyser in the boiler flue to improve boiler efficiency management, modifications at point of use to enable better control and reduced steam usage
Compressed air system modifications	Refurbishment of air reticulation system, installation of oil traps, water traps and pressure regulators, installation of variable speed drives on compressor motors, leak detection and repair, changes to control algorithms to improve the management of multiple compressors, elimination of unnecessary usage
Fleet fuel efficiency	Training of drivers in eco-efficient driving techniques, installation of satellite vehicle monitoring systems, modifications to vehicle components to improve aerodynamics
Motor efficiency improvements	Motor power surveys, replacement of standard-efficiency motors with premium-efficiency motors, motor shaft alignment and belt drive tensioning services, gearbox and coupling modifications, improvement of motor loadings through motor swaps/replacements
Lighting improvements	Installation of new fittings and efficient lighting solutions, rearrangement of switching to permit more effective zoning, modifications to allow lower-wattage lamp usage in existing fittings
Material usage reductions	Condition monitoring and calibration checks for material-critical equipment e.g. flow meters/load cells used to measure material flows
Reduction in maximum demand	Installation of a power factor correction system, supply and installation of soft starters, supply, installation and programming of a load demand controller
Reduction in electrical heating requirements	Insulation of equipment, installation of a temperature probe with feedback control, tuning of control loops
Improved waste management	Supply and commissioning of compactors to reduce haulage costs, outsourced waste management services, installation of recovery systems to allow reuse and/or to turn wastes into revenue streams
Reductions in cooling tower evaporation	Design and commissioning of integrated heat recovery systems to reduce heat rejection e.g. heat exchangers, piping, valves and control systems
Reductions in water usage	Supply and installation of low-flow shower heads, water filtration systems that allow increased reuse, treatment options etc.
Awareness	Training and coaching of staff

In a growing economy, the industrial sector would typically invest in capital projects, and hence jobs would be created at companies providing the types of services indicated above. However, the current economic situation means that many of these types of suppliers are without work. The beauty of resource efficiency projects is that they are not wholly dependent on the economic climate to be viable (though it is true that increased demand generally makes resource efficiency projects more financially viable). Resource efficiency projects are about doing more with less, and it is precisely at times such as now that they are most needed. In addition, when there is an uptick in economic activity, resource-efficient operations stand to benefit most from the increases in margins that come with the reduced costs per unit of production delivered by resource efficiency in areas such as energy, water and materials. Resource efficiency has a multiplier effect on profits in boom times.

Essentially, what we are doing when we develop and implement resource efficiency projects is creating a pipeline of projects for small businesses (and some large businesses too). In essence, deployment of the correct expertise and the use of specialist measurements creates “something out of nothing” by identifying opportunities that were hitherto hidden and which, if not implemented, would not prevent industrial operations from functioning, but which once implemented have a material effect on productivity and environmental performance. Recent increases in energy, water and material costs make many of these projects viable in their own right, but the South African government has also, through the DTI, recently launched incentives which will make them even more attractive.

What types of jobs am I talking about then? Let’s consider the example of a power factor correction system (more a cost reduction opportunity than a sustainability issue, but useful for illustration). Firstly, site power consumption would have to be logged over a period of time to determine demand trends and the variables necessary to understand variations in the site’s power factor. Some other parameters may also be of interest, for example harmonic distortion and variations in supply voltage. Next the size of the economic opportunity would need to be investigated, which implies an examination of utility bills and the potential savings that could be achieved by improving the site’s power factor. These would then require comparison to the costs of installation and maintenance of a new system or an increase in the capacitance of an existing system, along with the costs of other associated equipment e.g. harmonic filters. It is generally a good idea to look at this in conjunction with any other potential initiatives that could impact on demand, e.g. load management, energy efficiency projects etc. If viable, a power factor correction system would need to be designed, installed and commissioned. Performance would then need to be tested to ensure that expected improvements are realised. The system would then need to be maintained over the course of its useful life, or until circumstances on the site changed such that the system was no longer required. 

If we examine the life cycle of this small, relatively simple project, the following job roles are identified:

PROJECT TASK/PHASE	JOB OPPORTUNITY
Transformer logging	Logging equipment procurement (vendor) Conducting of logging (technician)
Financial review	Analysis of financial feasibility (financial analyst )
Supply of PF correction system	PF correction system parts procurement/manufacture/assembly (vendor)
Installation of PF correction system	Site prep, tie-ins, siting (technician, electrician, engineer)
Commissioning of PF correction system	(engineer, technician)
Testing of PF Correction system and confirmation of results	Technical and financial analysis (technician and financial analyst)
Maintenance of PF correction system	Assessment, preventive maintenance tasks and routine repairs to PF correction system over 20 year lifespan (technician)

The actual number of jobs created depends on a number of factors, but for each individual element of the value chain, clearly the more individual projects carried out by industrial sites, the higher the probability of creating new jobs. Local manufacture of the logger, power factor correction equipment and replacement parts required for maintenance would also mean increased local job creation, some of which would be in lower-skilled categories.

I have tried to illustrate the variety inherent in these types of projects, to show that even when implemented on a single industrial site, a wide range of small businesses can be touched. Now imagine if every industrial site in the country invested some time and energy in project identification and development. Each site would play host to a number of projects such as the one illustrated above. We would have an engine for significant job creation, not founded on charity, but on good business practice. In this win-win scenario, individual industrial sites would become more competitive, conduct their operations in a more environmentally and socially responsible way, and create jobs, many of which would be in the type of skill areas that sorely need development in South Africa. We would truly have a green job creation machine powered by the next wave of industrial productivity - sustainability.

CHARACTERISTICS OF SUSTAINABLE INDUSTRIAL ORGANISATIONS

What makes some organisations more sustainable than others? Is there a set of defining characteristics that organisations can aspire to that, if achieved, would improve their performance on sustainability issues? There is a general appreciation that the world is still learning about what sustainability really is and what it means for different industries. So what I want to explore in this post are some of the characteristics which I believe are important for organisations wishing to embark on the process of becoming more sustainable. These are my views, not the product of any research, but are of course founded on my observations of different industrial organisations and how they are managed, and which ones appear to be more successful at driving sustainability issues.

First and foremost, sustainable organisations have to be successful in economic terms, and hence many of the characteristics I will talk about will overlap with characteristics required of successful businesses in general. There are however some characteristics that are unique to sustainability-focused organisations and in reading this post, consider each characteristic within the context of sustainability rather than general business practice.

Sustainable Organisations are Outward Looking

Sustainability has a lot to do with how your organisation fits into the world, how it interacts and impacts on stakeholders and how quickly it can identify and assimilate best practices. All of these things require continuous scanning of the environment and ongoing interaction with stakeholders, followed by deployment of acquired learnings within the organisation. No man is an island, and certainly no sustainable organisation can be one either. Sustainable organisations keep abreast of environmental, economic and social issues impacting on their industry, and also are continually assessing what their contribution is to improvements in these areas within the broader environment within which they operate.

Sustainable Organisations are Innovative and Flexible

Balancing economics, the environment and social challenges, not just in terms of policy but as a fundamental way of doing business, is difficult, and requires innovation at all levels of an organisation. Becoming more sustainable implies constant change, new products, new processes, new ways of managing people, new ways of engaging with consumers, communities and staff and basically ongoing reinvention. This doesn’t mean making every business process an exercise in all-out creativity, but it does mean encouraging fresh thinking and being open to new ideas.

Core Employees within Sustainable Organisations are Industry Experts

While the principles of sustainability are generic, industrial sustainability presents very specific challenges to individual industries, along with a lot of generic ones. All industries largely face similar challenges and opportunities regarding the usage of electrical energy for example. However, the pulp and paper industry faces additional challenges in terms of persistent organic pollutants, the electroplating industry has to manage risks regarding heavy metal pollution, the coal-fired power generation industry has to mitigate sulphur dioxide pollution risks and spray painters have to manage employee exposure to volatile organic compounds, as examples of industry-specific challenges. Individual industries generally come with a number of key sustainability challenges. To effectively deal with these issues while still remaining profitable and not compromising other areas of performance requires deep industry knowledge, and sustainable organisations invest heavily in the development of this knowledge within their ranks. This is achieved through in-house training, strong internal mentorship programmes, structured training programmes for new recruits and the creation of opportunities for knowledge sharing and development.

The Dominant Paradigm within Sustainable Organisations is one of Integrated Thinking

Sustainability-minded organisations view individual issues as part of a larger whole and are always looking to optimise the system rather than individual processes. A piecemeal approach to individual problems with no consideration for how they relate to each other is a recipe for confusion, disarray and ultimately organisational paralysis. Becoming sustainable is not about achieving a single goal, but about finding an optimum position at which a number of often-competing objectives are met. This applies even more so to high-performance organisations. When you are coming off a low base, it is fairly easy to make simultaneous improvements in costs, quality, flexibility and other operational objectives. For organisations on the performance frontier, incremental improvements can often mean compromises, or where these compromises are unacceptable, additional investment to remove constraints. Organisations seeking to become sustainable are keenly aware of their limits, look at the whole picture (which is the big picture and the detail) and make choices accordingly.  This applies all the way through from the shop floor to senior management. Sustainable organisations also are very clear on the issues which cannot be compromised, such as compliance with legal frameworks and the safety of employees, local communities and consumers, as examples.

A Real Desire to be Responsible Drives Decision-making

The moral aspects of sustainability cannot be ignored, and if “being sustainable” is merely an organisational goal but is not driven by real organisational values that embrace responsibility, the chances are that success will elude your organisation. This applies even more prominently in poorly regulated environments, where organisations have to make their own decisions as to what “the right thing to do” is. The challenge here is that being responsible comes at a cost, and the temptation is to only spend what the organisation is forced to spend, rather than what should be spent to protect employees, the environment, local communities and consumers. I’m not referring here to the obvious things that any going concern would do, but also to the issues with longer term implications, such as long-term occupational exposures that are not regulated, but which do have an impact on employee health. The resource efficiency aspects of sustainability are easy to justify based on the short-term economic benefits, but matters of pollution prevention and safety tend to introduce costs in the short term that are not accompanied by immediate economic benefits. Sustainable organisations recognise however that in the long term, these are actually investments. This brings us to the next characteristic of sustainable organisations.

Sustainable Organisations take a Long-term View

Another apparent truism of good business practice, this is not only about being patient and avoiding instant gratification, but also about being cognisant of the cumulative impacts of the actions taken by the organisation in terms of potential harm. In industrial environments, acting quickly is of course imperative, since in high-volume operations, impacts can mount up very quickly. The trick here is to act quickly, but to take the sort of actions that are preventive, rather than corrective in nature. This means getting to the root causes of problems and putting systems in place to prevent their recurrence. It means being able to make a bigger investment now for larger cumulative returns in the future. It means understanding that short term decisions that compromise the environment can  come back to haunt the organisation at some point in the future, resulting in large potential liabilities and immense reputational damage, but even more importantly, that such decisions impose a cost on society.

Sustainable Organisations are Disciplined

When short-term returns are not forthcoming, discipline is essential. Sustainable organisations have the discipline to follow through, taking comfort in the knowledge that their actions are delivering results in the long term and building capacity. This is not based on blind faith, but on robust measurement systems that provide ongoing feedback, and reinforce sustainable behaviours within the organisation.  Discipline is also required to maintain high levels of operational performance. The most successful organisations have very clear documented practices (typically embedded within quality management systems) which are followed by all employees. Rigorous adherence to these practices is an example of the kind of discipline needed to achieve sustainability, and this adherence does not need to detract from the organisation’s ability to be innovative and flexible. Instead, documented practices are changed as improved practices become known, and their rigorous application means that discipline and innovation live comfortably side by side in sustainable organisations.

These are just some of my preliminary thoughts on the key characteristics of sustainable organisations. There are no doubt many others, and I would be keen to hear your thoughts. 

PRACTICAL ELECTRICAL ENERGY CONSERVATION ON INDUSTRIAL SITES - ARTICLE 3: HEATING

Electrical heating systems are common in industrial environments. They may be assumed to operate at very high efficiency levels i.e.  close to 100% of the electrical energy supplied to heating elements is converted to heat. Of course, generation of electricity is not a process that operates at 100% efficiency, and this has to be considered when assessing the overall emission impacts of using electrical heating systems.They also can have significant demand impacts, and as resistive devices with power factor close to unity, demand reduction through power factor correction is not possible.

Typical applications are for the heating of process fluids (e.g. solutions of chemicals used for washing, or for air used in drying) or sometimes for the heating of materials (e.g. heating of plastics during extrusion). Electrical heating may also be used for producing hot water and even steam.

Given the fact that heating is itself a very efficient process, energy savings associated with heating are unlocked by taking a systems perspective. Hence if you are analysing a steam system, you would need to consider the distribution and usage of steam and the recovery of condensate in order to increase the efficiency of the steam system, thereby reducing the electrical energy input.

      

In smaller operations I often see manual control being employed, particularly in batch processing environments, and generally I always recommend some type of feedback temperature control system, even if in the form of a simple thermostat. Any overheating represents a waste of energy, and also accelerates heat losses to the environment due to an increase in driving force.

An obvious opportunity with heated systems is the use of insulation to limit losses to the environment. Basically you want to close the system as far as possible, and this includes any open surfaces, as would be found in things like heated process baths and the like. The use of covers helps to limit losses to the environment. Heat losses from agitated liquid surfaces tend to be significantly higher than from still surfaces, and hence any agitation should be limited as far as possible. Obviously many processes require agitation for legitimate reasons, and it’s about finding a happy medium between your process goals and heat losses.

Heat loss occurs not only through direct heat transfer, but can also happen as a result of carryover of hot process fluids into downstream processes. This can happen easily in process such as electroplating, or washing. It’s clear that such carryover should be limited as far as possible, since not only is heat lost with the fluid leaving, this fluid is generally replenished with fluid at room temperature which has to be heated to the process temperature.

Depending on the heat load and when the heating is done, the rate of heating could impact on maximum demand charges, and you may want to look at how heat-ups of individual process vessels are scheduled at start-up.

Lastly, heated processes should be located in areas free from drafts (either natural or induced) since these increase the rate of heat transfer from hot surfaces and increase heat losses.

Let’s briefly explore what I mean by taking a "systems approach" by considering a simple process in which a tank cleaning solution is heated on a batch basis using an in-line heating element, with the cleaning solution circulated through a sprayball in order to clean the tank. Water is added to the tank, cleaning chemicals are added and the resultant cleaning fluid is circulated through an in-line heater and back into the tank to be cleaned. After cleaning, the fluid, which becomes soiled, is drained. The system is shown in the diagram below. 

Important basic issues to consider would be:

Is there a temperature probe used for feedback control of the heating operation? Without control of the temperature, the fluid could be heated excessively, wasting energy. If a probe is installed, what is the temperature used for cleaning? This should be as low as is practically possible in order to reduce energy requirements for heating up the cold cleaning fluid. Lower temperatures will also translate into reduced heat losses to the environment due to a reduced driving force for heat transfer;  Is the system well insulated? This includes the vessel as well as the piping used to circulate the cleaning fluid;  What volume of fluid is used for each cleaning operation? The larger this volume, the greater the sensible energy requirement for heating the fluid up;  How often is the cleaning operation performed? – clearly the less frequently this can be done (while still meeting all other process goals, such as sterility for example) the lower the energy requirements for cleaning; Instead of a once-through cleaning system with the cleaning fluid discarded after each wash, is it possible to collect and reuse the fluid, if not for subsequent cleaning, then for other purposes in the facility? Integrating this washing process into other processes in the factory would lead to reduced facility-wide energy consumption.

    

     While heating elements are essentially simple devices, the systems within which they operate can be quite complex, and optimising these systems in an integrated fashion is the challenge when seeking to reduce their energy consumption.

HEAVY METAL POLLUTION OF WATER RESOURCES - CAUSES AND IMPACTS

The term “heavy metal” is not altogether clearly defined, but in the case of water pollution, these are metals such as arsenic, cadmium, iron, cobalt, chromium, copper, manganese, mercury, molybdenum, nickel, lead, selenium, vanadium and zinc. While heavy metals do tend to have a high atomic mass, and so are heavy in that sense, toxicity seems to be a further defining factor as to what constitutes a heavy metal and what does not.

Municipal treatment plants are generally ill-equipped 
to cope with significant heavy metal pollution, both 
in terms of removal and safe sludge disposal.

Heavy metals occur in the earth’s geological structures, and can therefore enter water resources through natural processes. For example, heavy rains or flowing water can leach heavy metals out of geological formations. Such processes are exacerbated when this geology is disturbed by economic activities such as mining. These processes expose the mined-out area to water and air, and can lead to consequences such as acid mine drainage (AMD). The low pH conditions associated with AMD mobilise heavy metals, including radionuclides where these are present.  Mineral processing operations can also generate significant heavy metal pollution, both from direct extraction processes (which typically entail size reduction - greatly increasing the surface area for mass transfer - and generate effluents) as well as through leaching from ore and tailings stockpiles.

While mining activity poses significant risks for heavy metal pollution, this sector is not the only culprit in the industrial sector. Many industrial processes can generate heavy metal pollution, and in a large number of ways. Clearly, some industries will be more likely to pollute than others. Hence the electroplating industry, which can produce large volumes of metal-rich effluents, will naturally be a more likely polluter than the food processing industry, for example. This is not to say that players in this industry will necessarily pollute, and it is in fact in the electroplating industry’s best economic interests to minimise metal discharges, since these are inversely proportional to resource efficiency. Reducing losses by minimising drag-out from plating baths leads to reduced metal discharges, for example. The lead-acid battery manufacturing industry is another example of an industry which can generate metal-rich effluents as well as airborne lead pollution which can subsequently be deposited in surface water resources (and of course on land). So clearly, where an industry uses heavy metals as key input materials, pollution risks increase.

  

An example of a large non-point source of heavy metal pollution is coal-fired power generation, which can contaminate water resources through aerial deposition of mercury emitted from boiler flues. Technologies such as wet scrubbing are available to remove much of this mercury, but of course the effluents produced have to be safely handled to prevent subsequent pollution. Some of these processes have the primary goal of removing sulphur dioxide, with heavy metal removal a welcome by-product of the scrubbing process. The industry also generates large amounts of ash which itself contains heavy metals, including uranium. 

The importance of minimising heavy metal pollution for industrial organisations extends beyond simple compliance. The impacts of heavy metal pollution on living organisms are very serious. Heavy metals are bio-accumulative, toxic at high concentrations, have neurological impacts, and some are carcinogenic. They can also interfere with chemical processes by poisoning chemical catalysts and can impact on biochemical processes by interfering with enzyme action. There are hence serious environmental, economic and social impacts associated with heavy metal pollution. 

As always, a detailed risk assessment, which must include include quantitative measurement, is recommended to help you to understand your heavy metal pollution baseline. Where problems are identified, the solutions you choose should focus on the source of the pollution as far as possible, in line with Cleaner Production principles. End-of-pipe treatment methods are unavoidable in many circumstances, but where they are employed, care should be taken to dispose of resultant concentrated metal wastes safely. For example, lime treatments, which raise pH and precipitate metals, produce concentrated wastes (sludge) requiring safe disposal, as do processes such as reverse osmosis (retentate). Take care then that you are not just moving the problem around through poor management of these wastes, which generally require disposal at certified hazardous waste installations.