Principles and Practices in Sustainable Development for the Engineering and Built Environment Professions 

Unit 2 - Efficiency/Whole Systems

 

Lecture 6: Engineering Energy, Water and Material Efficiencies

         

Educational Aim

 

Effective practitioners have shown that it is possible to achieve significant energy, water and material efficiencies with numerous everyday products and industrial processes. The goal here is to introduce and start to explain how to achieve such results, and how still greater results can be achieved in the future. A succinct overview of these exciting opportunities for engineers is outlined with checklists to provide guidance for those seeking to achieve greater energy, water and materials efficiencies. These checklists have been developed and formally published by The Institution of Engineers Australia and the Institution of Professional Engineers, New Zealand.

 

Required Reading

von Weizsacker, E., Lovins, A.B. and Lovins, L.H. (1997) Factor 4: Doubling Wealth, Halving Resource Use, Earthscan, London, Introduction: More for Less.

Hargroves, K. and Smith, M.H. (2005) The Natural Advantage of Nations: Business Opportunities, Innovation and Governance in the 21st Century, Earthscan, London:

1. Introduction: Insurmountable Opportunities (4 pages), pp 1-4.
   
   
   

Learning Points

1. Because much energy is lost in the transmission of energy and water from the power station or dam to the consumer energy, water and material efficiency can provide significant reductions to the ecological footprint and greenhouse gas emissions of processes.

2. Energy, water and material efficiencies have a cascading effect, reducing significantly the overall environmental load of any engineered system (industrial processes, built environment, or product) on the biosphere. Small increases in end-use efficiency can reverse these compounding losses. For instance, saving one unit of output energy can cut the needed fuel input by up to 10 units at the electricity power station.[1]

3. Engineers have a critical role to play to ensure that both the process of creating products and the actual products themselves are as resource efficient (water, energy, material efficient) as possible over the lifetime of their use.

4. Engineers have shown that it is possible to re-design and re-optimised numerous everyday products to achieve up to as much as 90 percent energy efficiency savings. Engineers and architects have shown that it is possible to design buildings so that during their day to day operation they need 30-80 percent less energy and water than conventionally designed buildings. There is now decades of documented experience by engineers in peer reviewed literature, journals and books of how to achieve this for most areas of engineering.[2]

5. There is significant interest improving resource efficiency because it fundamentally makes good business sense. Using energy, water or materials more efficiently offers an economic bonus because saving resources is a lot cheaper than buying them.

• Over the past decade, chemical manufacturer DuPont has boosted production nearly 30 percent but cut energy use 7 percent and greenhouse gas emissions by 72 pecent (measured in terms of their CO2 equivalent), saving more than US$2 billion. Five other major firms—IBM, British Telecom, Alcan, Norske Canada and Bayer—have collectively saved at least another $US2 billion since the early 1990s by reducing their carbon emissions more than 60 percent.[3]
  
  
• Car companies that have invested in energy efficient cars are finding that this is a highly profitable part of their business especially with historically high oil prices. General Electric has committed to making its products and appliances as efficient to run as possible. These energy efficient products now constitute US$10 billion per annum in sales.
  
  
• Full cost studies of the financial and economic analysis of the benefits of water efficiency are in their early stages. But research undertaken by the UTS’ Institute for Sustainable Futures in Australia, for regulators and utilities across Australia, indicates the value of such research. Their research suggests that for cities and towns facing water supply augmentation, investment in water efficiency can result in water savings of greater than 30 percent at a unit cost that is less than supply augmentation, yielding net present value economic benefits in excess of AUS$100 million for some capital cities.
  
  

6. A significant ingredient in achieving increased resource efficiency is the reduction in raw materials consumed to provide the goods and services. A key incentive to address materials use is that reducing the amount of input materials, ultimately reduces the amount of waste generated. This reduces purchase and disposal costs and benefits the product’s economic performance.

7. Efficiency improvements can also make distributed approaches to energy and water supply much more cost effective. This can create economically viable ways to achieve truly sustainable energy and water supply solutions utilising distributed energy and water approaches.

8. To help guide engineers to achieve dramatically improved energy, water and materials efficiencies checklists are provided (see Brief Background Information). These checklists are a guide and should not be seen as a substitute for life cycle analysis. To ensure that all efficiency opportunities are identified and seized it is vital that the right questions are asked. Ideally all engineering projects would employ a life-cycle approach to their designs (industrial plants, built environment projects and products) to identify where large efficiencies savings are possible. Often the results of a Life Cycle Analysis (LCA) can yield surprising information about where the highest environmental impacts actually exist and therefore where efficiency initiatives will be most effective.

9. An important way to measure the ecological stress potential of goods and services is the ‘Material Intensity Per unit Service’ or ‘MIPS’. This is a tool that can be used to begin to discuss and understand material flows through society and their ecological implications. MIPS is measured in material input per total unit of services delivered over its life cycle. This includes the time from resource extraction to manufacturing, transport, packaging, use and re-use, recycling, and final waste disposal. MIPS goes beyond direct inputs to include the hidden costs of materials and energy - preliminary estimates have been made for a number of materials and energy flows, and there is significant work yet to be undertaken in this field.

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Brief Background Information

 

(A) Checklist for Energy Efficiency in Process - Improving Efficiency with Small Financial Investments.[4]
If you are employed in the Process Industries and your company has not looked in detail at energy use before, chances are that simple changes can save energy and resources at minimal cost or with substantial savings. Internationally, policy on greenhouse gases and energy efficiency is heading towards setting standards for each industry and process related to units of production. For the reasons listed below, a preliminary audit may well be worth the time and resources. Ignorance is never bliss for a practising engineer - the following checklist aims to assist in improving energy efficiency.

Energy efficiency should be considered if you are involved in any industry using power/heat, particularly cement, paper, steel, textiles, non-ferrous metals, chemicals, food or wood products.

Improved energy efficiency may be achieved using a simple five step process:

1. Obtain Senior Management endorsement for the concept.
   
   
2. Perform an energy audit to assess the present situation.
   
   
3. Process the audit data – identify opportunities for energy efficiency and set targets.
   
   
4. Implement changes.
   
   
5. Monitor progress (data tracking).

Step 1. Obtain endorsement from management

Arguments in favour of targeting energy efficiency are:

• increased competitiveness and reduced costs (material inputs/fuel, maintenance, personnel)
  
  
• ability to defer major capital investment by using demand side management
  
  
• increased efficiency and conversion efficiency
  
  
• improved product through increased focus on quality systems
  
  
• public relations benefit of ‘being green’ (e.g. Greenhouse Challenge)
  
  
• improved health and safety record through improved housekeeping
  

Step 2. Perform energy audits
Identify energy sources:

• fuel type (gas, oil, diesel, other)
  
  
• electricity (imported, generated in-house)
  
  
• heat (steam, waste heat recovery)
  
  
• compressed air
  
  
• water or other

For each energy source:

• determine quantity of energy used, cost per unit
  
  
• standardise unit to enable comparison
  
  
• identify sources of information about energy use include energy bills, metering (accuracy?), staff, design books (compare design vs. actual)

Identify conversion processes and major energy uses:

• determine where energy is used
  
  
• production (major equipment items, systems, plant sections)
  
  
• administration/buildings/storage
  
  
• maintenance
  
  
• transport/goods handling
  
  
• determine whether the use is fixed or variable relative to production rate
  
  
• use energy and mass balances to determine, efficiency of conversion processes, losses, especially batch processes and waste disposal
  
  

Include the following items in site-specific audits:

• maintenance
  
  
• leaks/loss of containment (fuel/utility systems)
  
  
• loss of energy (uninsulated surfaces) poorly tuned equipment (process control equipment)
  
  
• poorly maintained equipment (clogged filters, sticking control valves) operations
  
  
• standby/redundant equipment on idle rather than shutdown?
  
  
• excessive reject rate/ waste production/off spec product recycling potential?
  
  
• inefficient manual handling and storage procedures?
  
  
• preventable shutdowns causing energy/product loss?
  
  
• co-ordinate prodition to avoid peak loads on energy systems?
  
  
• allowing for ambient conditions (compressor air inlet cooling off in cool weather, ramp back heat tracing on hot days)
  
  
• reduce cooling and heating
  
  
• requirements by operating systems at optimum
  
  
• through improved process control optimise batch sizes with storage to meet demand (larger, less frequent batches?)
  
  
• transport/storage
  
  
• streamline contracts with suppliers to minimise storage
  
  
• optimise storage to minimise handling
  (e.g. liquids in 1000L bulky boxes rather than 20L drums) + size vehicles appropriately, allowing for multiple uses + switch off while not in transit, optimise loading facilities to minimise time and resources (automate?)

Administration/buildings:

• comply with the latest Code of Practice for efficiency lighting, air conditioning, equipment use (e.g. replace incandescent lights with fluorescent)

Design:

• non-integrated heat or pressure systems
  
  
• pressure reduction followed by recompression.
  
  
• heat loss from hot stream while cold stream heated by additional heat source
  
  
• waste heat utilised to preheat feed pressure
  
  
• over-design of safety lighting,
  
  
• air-conditioning (especially switchgear rooms etc.)
  
  
• batch processes - modify to semicontinuous/ continuous
  
  
• replace equipment with newer, more efficient, lower maintenance type
  
  
• minimise electricity use where possible (use alternative fuel)
  
  
• conduct energy efficiency audits on all new plants/equipment
  
  
• oversized equipment - replace with smaller equipment in parallel
  
  
• substitute fuels to improve efficiency.
  
  
• utilise waste products as fuel (e.g. solvent recovery from drying operations)
  
  
• use variable speed drives

(B) Water Efficiency Checklists (Water Efficiency, Reuse and Recycling Checklists)[5]
Water is essential for all life. It is also integral to economic development, community well-being, and cultural values. To be sustainable, supply and use of water must ensure that today's water needs are met equitably and in a manner that protects essential ecological processes and allows future generations to meet their own water needs. These requirements influence all aspects of water supply, use and disposal, which include:

• The sources of water we choose.
  
  
• The ways in which those sources are tapped.
  
  
• The level of consumption of water by individuals, industry and agriculture.
  
  
• Access to acceptable quality water for all people.
  
  
• Water supplies for ecosystems maintenance.
  
  
• Effect of human activities on water resources.

Using Water More Efficiently
To manage water in a sustainable manner available resources should be used as efficiently as possible. Efficient water use not only conserves limited supplies, it also saves money in a number of ways, such as:

• Eliminating or delaying need for constructing new dams or wells.
  
  
• Decreasing quantity of water to treat.
  
  
• Decreasing quantity of wastewater to treat.
  
  
• Reducing size and cost of pipes, pumps, and other infrastructure.
  
  
• Lowering customer costs.
  
  
• Reducing energy used (and energy costs) for heating water.
  

Reduced consumption of water also has other benefits, such as making more water available for environmental flows in rivers to protect aquatic life, providing greater security against droughts and allowing for economic and population growth. Some of the ways in which water can be used more efficiently are:

• Have you carefully accounted for water use throughout the entire design process?
  
  
• Use of more efficient plumbing fixtures, such as low-flow showerheads, water-efficient toilets, and tap aerators.
  
  
• Use of more efficient equipment, such as dishwashers and washing machines pressure reduction grey-water.
  
  
• Use water-efficient landscaping.
  
  
• Use of efficient irrigation systems.
  
  
• Water reuse and recycling.
  
  
• Cooling water recirculation.
  
  
• Recycling of rinse waters.
  
  
• Redesign of manufacturing process to reduce water use leak detection and repair.
  
  
• Water main rehabilitation metering and sub-metering.
  
  
• Water audits.
  
  
• Retrofit programs.
  
  
• Pricing, eg higher unit rates for greater use.
  
  
• Surcharges on excessive use, time-of-day.
  
  
• Pricing.
  
  
• Labelling of water-using equipment.
  
  
• Consider water from aquifers, rainwater, surface run-off water.

Treating Wastewater and Stormwater as Resources
Both wastewater and stormwater have been regarded as waste products to be disposed of as efficiently as possible. Two factors are changing perceptions of these products: 1) disposal is becoming more problematical, with both wastewater and stormwater being seen as major sources of pollution; and 2) at the same time, increasing demands for water coupled with limited access to new supplies, makes consideration of alternative sources more compelling. Reuse of grey-water is also receiving new attention.

• Consider water from rainwater, surface run-off water, grey-water, and any water use for sewage transport or processing systems within a cyclical concept.
  
  
• Consider new ways to treat wastewater using organic treatment systems?
  
  
• Consider whether your designs consider rainwater and surface run-off water as much as possible for water resource use in infrastructure systems and processes.
  
  
• Treat grey-water and apply it to practical or natural purposes suitable to its characteristics?
  
  
• Minimise contamination and put any water used in any process related activity back into circulation if possible.

Water Reuse and Recycling
Water reuse is the use of wastewater or reclaimed water from one application such as municipal wastewater treatment for another application such as landscape watering. The practice of using wastewater for irrigating agricultural crops is hundreds of years old, but it lost favour for many years. Water recycling is the reuse of water for the same application for which it was originally used. Recycled water might require treatment before it can be used again.

Benefits of Wastewater Reuse and Recycling

For Municipal and Regional Authorities

• Reduces the demands on available surface and ground waters.
  
  
• New water sources may be unavailable or controversial.
  
  
• Delays or eliminates need to expand potable water supply and treatment facilities.
  
  
• May be less expensive than building more reservoirs.
  
  
• May reduce cost of wastewater treatment.
  
  
• May reduce the amounts of nitrogen, phosphorus and other pollutants being discharged to water bodies.
  
  
• Reduced need to transport water long distances.
  
  
• Sale of treated water may offset costs of wastewater treatment provides free fertiliser (owing to high levels of nutrients present) provides opportunities for economic development.

For Industry

• Reduces cost of purchasing, treating and disposing of water.
  
  
• Collects contaminants which need proper management.
  
  
• May allow reclaiming of valuable materials which would otherwise be discharged.
  

Complementary Strategies

• Making better use of water reduces the amount to be supplied - from any source.
  
  
• Pricing, education and information, building and planning regulations and other techniques used to improve efficiency and reduce demand stringent policies to maintain quality of wastewater sent to sewage treatment (to minimise heavy metals and toxic materials).
  
  
• Programs to minimise leakage of stormwater into sewers.
  
  
• Integrated catchment management to provide an overall strategic approach to all water issues.

Potential Uses of Recycled Water

• Dependent on level of treatment applied, health regulations, and requirements for use.
  
  
• Irrigation of landscapes, golf courses, woodlots, and some agricultural crops.
  
  
• Water for power stations and other industrial uses.
  
  
• Fire-fighting.
  
  
• Restoration of wetlands.
  
  
• Some recreational uses.
  
  
• Ultimately for conversion to drinking water.

Treatment of Wastewater for Reuse and Recycling

• Level of treatment depends on proposed uses and environmental and health regulations.
  
  
• Reuse for irrigation and other uses that involve spreading water over land removes nutrients, and may eliminate the need for nutrient removal that would be required for discharges to surface waters.
  
  
• Reused wastewater has most commonly received secondary treatment; higher levels of treatment would be required for potable supplies.
  
  
• There is a need to match suppliers and users.
  

Issues regarding Wastewater Reuse and Recycling

• Health regulations place constraints on some potential uses.
  
  
• Public education is required to overcome concerns about risks associated with reuse.
  
  
• When using wastewater for irrigation and landscape watering, there is the same need to ensure that runoff containing pesticides and other chemicals does not create pollution of ground or surface water.
  

Checklist for Stormwater Management
Vast quantities of runoff water have traditionally been discarded into surface waters using extensive networks of drains and channels. Studies in Adelaide, for example, showed that the amount of stormwater runoff was approximately equal to the total water use of the city. The quality of stormwater is often poor because of contamination with oil and heavy metals from cars, animal and garden wastes, as well as cigarette butts, litter, and other pollutants. Discharge of large quantities of runoff immediately after storms commonly has a serious detrimental effect on receiving waters. The main driving force for taking a new approach to stormwater management has been the concern about pollution of surface waters, but the vast quantity of water available is leading to recognition that stormwater is also a valuable resource.

Land use and transport policies have led to large paved and built areas. Although soil will absorb rainwater, pavement will not, so in today's developed areas the volume and speed of runoff are many times higher than before development. Approaches to stormwater management have to address the range of issues contributing to problems resulting from runoff.

Techniques for Reducing the Contamination of Stormwater
Controlling soil erosion from construction by:

• maintaining vegetated areas,
  
  
• limiting the amount of bare soils,
  
  
• diverting peak flows around sensitive areas,
  
  
• stockpiling of sand, gravel. soil etc. in a manner that prevents washing into roads
  
  
• minimising cut and fill operations
  
  
• minimising vehicle activity during wet weather
  

Developing readily available systems for recycling used oil.

Green waste collecting and composting.

Encouraging car washing on lawns, not on roads.

Pet owner responsibility for collecting animal wastes.

Education of the community about stormwater issues.

Reducing Stormwater Flow
Other approaches primarily aim to reduce the quantity and speed of stormwater flow. These include:

• Finding and eliminating illegal discharges.
  
  
• Preserving natural drainage systems such as streams and vegetative buffers.
  
  
• Reducing urban sprawl.
  
  
• Use of vegetative filter strips and trees that remove pollutants and lessen erosion by holding the soil in place.
  
  
• Mulches to help stabilise bare soils and reduce erosion
  
  
• Low-maintenance landscapes or ‘xeriscapes’ utilising native and adapted plant species and improved management practices to save water; lowering runoff by lessening the amount of water that's applied. (Fewer chemicals are applied, so pollution from pesticide runoff is also reduced).
  
  
• Porous pavements, used for streets and car parks, remove soluble and fine particle pollutants while increasing groundwater recharge. If properly designed, most of the runoff can be stored and will infiltrate into the ground where it can be used by trees and other vegetation.
  
  
• Structural controls include protective coverings of crushed stone, gravel, interlocking plastic meshes, and other measures.
  

Capturing Stormwater
A third set of techniques is designed to capture stormwater and use it for beneficial purposes. Generally such techniques involve creation of new green spaces and waterfront landscapes that can enhance property values. In some cases, the stormwater is retained only temporarily to reduce peak flows of contaminated water; in others the water is retained over the longer term. These techniques may be combined with treatment of the stormwater using sand filters or other means. Examples of the beneficial use of stormwater include:

• Detention basins (both temporary and extended).
  
  
• Retention ponds (water infiltrates into soils).
  
  
• Constructed wetlands urban forestry projects recreation areas.
  
  

Constructed wetlands can remove nearly 80 percent of suspended solids and lead and more than half of the total phosphorus found in typical urban runoff. Wetlands also decrease flood flows and increase wildlife habitat.

C) Materials Efficiency - Adapted from the Solid Waste Checklist[6]

1. Have you taken all reasonable steps within the scope of the project (and/or work environment) to eliminate, reduce or manage demand for materials use to avoid the production of waste?
   
   
2. Have you included materials efficiency and waste minimisation requirements into requests for proposals from contractors (eg specified tenders use recycled content, reusable materials or reduce waste generated by the project as much as possible)?
   
   
3. Have you written solid waste contracts that incentivise waste reduction and introduce differential pricing to promote waste reduction?
   
   
4. Can you evaluate proposals or potential jobs with some consideration given to materials efficiency and waste production?
   
   
5. Can you establish a preference for materials and products that are: made from renewable, sustainably acquired materials; have recycled content; durable; low maintenance; non-toxic or low toxic; recyclable; and low polluting in manufacture, shipping, and installation?
   
   
6. Can you use your knowledge of sustainability to educate and suggest alternatives for product production, materials use and waste management options (eg using life cycle analysis tools to guide decision-making processes on best use of materials and energy)?
   
   
7. Have you considered all the various initiatives that could assist with waste minimisation (eg taking direct action like: recycling or composting; education and consultation; legislative changes; research and development; and monitoring and feedback)?
   
   
8. Can you quantify and apply the real costs of materials use, and waste generation and disposal to your project?
   
   
9. Can you use the discharge from one process as a resource for another (eg application of bio-solids to land for soil conditioning or use of wastewater as heating)?
   
   
10. Have you provided specifications and dimensions that minimise waste?
    
    
11. Can you establish targets for waste toxicity reduction and monitor them?
    
    
12. Can you design your product or asset for disassembly of materials and systems?
    

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Key References

- Pears, A. (2004) Energy Efficiency - Its Potential: Some Perspectives and Experiences, Background paper for International Energy Agency Energy Efficiency Workshop, Paris April 2004. Accessed 5 January 2007.

- Department of Industry, Tourism and Resources (2006) Energy Efficiency Opportunities Assessment Handbook, Commonwealth of Australia ISBN 0 642 72523 3. Available at www.energyefficiencyopportunities.gov.au/handbook. Accessed 5 January 2007.

- Australian Greenhouse Office (n.d.) Energy Audit Tools. Accessed 7 January 2007.

- UK Carbon Trust: (2007) Savings By Technology UK Carbon Trust. Available at http://www.carbontrust.co.uk/energy/startsaving/technology.htm. Accessed 3 February 2007.

- UK Carbon Trust (2007) Energy Efficiency Savings Opportunities: By Sector, UK Carbon Trust. Available At http://www.carbontrust.co.uk/energy/startsaving/sector.htm. Accessed 3 February 2007.

- Rocky Mountain Institute (n.d.) Water Library. Available at www.rmi.org/sitepages/pid172.php#W04-21. Accessed 3 February 2007.

- Sydney Water (n.d.) Tips for Business on Saving Water. Available at www.sydneywater.com.au/SavingWater/InYourBusiness/. Accessed 3 February 2007.

- International Water Management Institute (n.d.) Homepage. Available at www.iwmi.cgiar.org. Accessed 5 January 2007.

-University of Technology Sydney (UTS) – The Institute for Sustainable Futures (n.d.) Homepage. Available at http://www.isf.uts.edu.au/. Accessed 5 January 2007.

-von Weizsacker, E., Lovins, A.B. and Lovins, L.H. (1997) Factor 4: Doubling Wealth, Halving Resource Use, Earthscan, London.

- Chapter 1: Twenty Examples of Revolutionising Energy Productivity;

- Chapter 2: Twenty Examples of Revolutionising Materials Productivity (including Water).

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Key Words for Searching Online

Energy Efficiency, Water Efficiency, Decentralised Energy, Factor-10 Institute, Wuppertal Institute, Rocky Mountain Institute, Material Input Per Service unit.

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[1] Rocky Mountain Institute (1997) ‘Cover Story: Tunnelling through the Cost Barrier’, RMI Newsletter, Summer 1997. Available at
http://www.rmi.org/images/other/Newsletter/NLRMIsum97.pdf</