The right topic at the right time was chosen this year for the Chamber of Engineers annual conference. CoE president Ing. Alexander Tranter opened last week's conference with a call to promote more strongly the widespread use of solar energy and other types of alternative energy. He referred to a "need to dispel irrational public fears on a number of environmental challenges our country now faces" .
Some major decisions that lie just ahead hinge on matters of technical fact, he said. Engineers are among those who must take on responsibility and can no longer sit on the sidelines. Government, on its part, should consult engineers before taking such decisions. More transfer of knowledge is needed to bring about a balanced view so that the public can make their own judgments about infrastructural developments.
In his opening address to the conference, Minister George Pullicino said that the EU was not just about financial assistance but also about setting the pace in environmental policy. Sir Martin Laing, a former Worldwide Fund for Nature chairman, acknowledged that engineers are professionals who have the knowledge to mitigate the footprint of projects on the environment.
"The EU is going to have greater and greater implications on everything Malta does. Changing the environment will require a different sort of leadership, offering an opportunity for engineers, " he said. Sir Martin asked what was being done in Malta to promote water saving techniques and design. He noted that buildings would soon have to carry and identity tag regarding the sustainable content of materials. Timber from forests which are not certified as sustainably managed should not be specified, he advised.
A technical expert on thermal waste treatment, Hubert Grech from the Austrian Environment Ministry, spoke on incineration and mechanical biological treatment (MBT), which separates out the high calorific fractions of waste to be incinerated.
Austria depends on grate-fired incinerators for municipal solid waste (MSW) but resorts to fluidised bed incinerators, a costlier type, for sewage sludge. The city of Vienna is now planning to build another municipal solid waste incinerator. Mr Grech claimed that Austrian NGOs had agreed that this was the best option. An existing plant makes cleaned flue gas readings available via Internet on a board displayed in the street. Some industrial plants in Austria already co-incinerate by burning plastics and used tyres at a cement plant. Some sludge left over after waste water treatment is incinerated at a pulp mill.
Mr Grech advised engineers to draw up a material flow chart to understand where hazardous materials might end up. In general this has indicated that mercury from incineration often ends up in "filter cake" which builds up in filters. Mechanical biological treatment sees 70% of cadmium content entering landfills. In conclusion, he said the wisest path was to develop individual solutions depending on local circumstances.
During question time a participant noted that since waste wood is used up in Malta by bakeries as fuel, while paper is shredded to make up for the lack of straw as animal bedding, the remaining portion of waste is of a low calorific value and unsuitable for incineration. Asked whether incineration might discourage separation of waste, Mr Grech noted that it was very difficult to recycle soiled or mixed plastics.
Questioned on the cost of incinerator technology, Mr Grech acknowledged that incineration was "a very expensive solution" and estimated that an average-sized plant could cost up to €150 million. Following installation, yearly maintenance costs are also known to be on the high side according to figures from the European Environmental Agency.
'The monster we need to tame'
Speaking on the rehabilitation of Maghtab, WasteServ executive Christopher Ciantar referred to the decision to maintain part of the dump renamed as Ta' Zwejra, using the part of Maghtab which had cooled down enough to allow the deposit of more fresh waste.
Depositing waste on the Salina side of the dump, where fires are fanned on the windward side, had become impossible. Surface temperatures in this area have been measured at up to 331°C.
Depositing more waste on the parts of the dump where underground fires still burned would have been similar to capping in effect. The idea of capping the dump without controlling the temperatures was abandoned since this might drive up internal temperatures, which would damage the cover. It was found that rain falling on Maghtab actually drives more oxygen into the dump, increasing the fires.
The primary objective of collecting the combustible gases from inside the dump, and directing them to an on-site mobile after-burn facility, is to destroy the pollutants, then recover energy. Two gas circuits will be in use: one to burn clean methane for beneficial use; and another for contaminated gases. It is not expected that the fires will be put out immediately through this intervention.
Adopting aerial emissions control is the next imperative step on the long road to full rehabilitation. A tender has been issued with offers to be received by the end of this month with the outcome expected to be concluded by the end of September.
This phase of the project must be complete by mid-2007 to benefit from EU funding. WasteServ appears to have successfully fulfilled an earlier commitment to come up with the rehabilitation strategy for uncontrolled waste dumps at Maghtab, Wied Fulija and Qortin (Gozo) by 2004.
Other rehabilitation measures include the isolation and containment of solid hazardous waste and enhancing stability to reduce the risk of sudden ground movements. The presence of hydrogen sulphide, which has resulted in fatal accidents for Maltese workers, is a concern for which safety procedures will be put in place.
Engineer Ciantar said that although dioxin levels were still within EU criteria for agricultural soils, the situation could get worse if nothing was done. Monitoring would ensure that it was not degrading more rapidly than thought.
Consultations are being held on possible future after-uses of the ex-dumping ground. To date a total of 15 quarries have been used for the deposit of building waste from construction and development activities.
Offshore wind farm potentials
The long-term cost and efficiency advantages of larger wind turbines over smaller models make the initial expense of offshore windfarms more attractive. Higher aerodynamic efficiency and the potential to harness stronger winds at higher altitudes combine with lower maintenance costs for rotor blades of 100 metres across. The need to space turbines of this scale well apart to avoid interference means that just three turbines would take up one square kilometre.
Despite the scarcity of suitable sites in Maltese waters which provide a workable depth for bolting wind turbine pylons to the seabed, some scattered locations do offer potential. The first area of choice would be a reef off Comino with other shallow sites identified off Ghallis, Benghajsa and Marsalforn. The total wind potential for all these sites combined is roughly estimated to reach over 100 megawatts or over 20 per cent of Enemalta's current output.
Scientists have noted that offshore windfarms in Denmark are acting as artificial reefs, claiming that they have increased fish populations. Studies on bird casualties have shown that 80 per cent of migrating birds are able to steer clear of windfarms. Engineer Tonio Sant, who has worked on aircraft maintenance, suggested that creating bird sanctuaries with an aim to diverting migration paths might be considered as a mitigation measure.
Specialising in wind turbine aerodynamics, Mr Sant predicts that with growth in the global wind industry at 20-25 per cent yearly, Malta must start playing a serious role and think ahead. In his assessment of Malta's wind farm planning and development in the years to come he envisages installation costs on the seabed (up to 70 per cent of initial investment) will continue to go down. Economic viability can only be accurately determined over a two-year period during which data for high altitude wind force (obtained from a minimum 60-metre instrument tower at sea) must be measured. A geological survey would also help determine the suitability of the seabed for driving foundation pylons into the rock.
As a first step, setting up an onshore wind farm to get aquainted with wind energy conversion before setting out to sea with the venture would reduce any investment risks. Up to 15 turbines could be installed on land to gain experience and fulfil EU renewable energy targets. As soon as offshore costs fall within reach operations can be expanded seaward.
Buildings, bio-fuel and batteries
Greener buildings are the latest target for property managers and designers now facing rising energy costs and new regulations. Tenants living in "intelligent buildings" find they can save money from better control of their energy consumption.
Monitoring and logging energy use identifies activities leading to excessive energy consumption. Clients who do not pay their utility bill may be encouraged to comply with an automated energy cut-out system. Maximum kilowatt demand, night or day use and power factor can be more readily taken into account for billing purposes.
Architectural features at the design stage enhance the use of solar energy and natural daylight. Most attention revolves around heating, ventilation and air-conditioning which are the main energy consumers. Sensors can provide feedback and optimise control or alert maintenance staff to clogged air filters which might cause an unhealthy environment in the workplace. Alarm notifications can be transmitted by e-mail or SMS.
Control strategies can be used, for example, to shut off the airconditioning in an office when someone opens a window. The rise in temperature persuades them to shut it again to restart the cooling system in an automatic response. A well engineered solution integrates all systems into a computerised central management system. Schedule or calendar functions activate shut down at night or during public holidays.
These concepts are best designed in at the planning stage as major improvements to existing buildings can prove costly. Among buildings in Malta already taking advantage of smart green systems are Whitehall Mansions, the Malta Stock Exchange and St Vincent de Paul home for the elderly. Reporting on intelligent controls for buildings, Project Manager Bernard Brincat, AIS Ltd, noted that environmental efficiency of buildings is now an established concept in EU legislation.
The cost entailed by Water Services Corporation to unblock drains clogged with discarded waste oil has amounted to Lm565,000 annually while it is calculated that 3,600 litres of oil are still being poured down the drains after use. A scheme to collect waste oil from 17,000 households will be launched with WasteServ's help next month. Maltese homes and restaurants produce 5,000 tons of waste oil each year.
Converting a readily available waste resource such as cooking oil into a cleaner fuel alternative has been the proud achievement of the Edible Oil Refining Company. Pilot testing on company cars (and boats) started in 1999 but refinement to present day quality of EU standards took three years of hard work.
Commercial manager Pippo Psaila stressed the ease with which bio-diesel, currently sold exclusively from the EORC pump at Marsa, can be used in any proportion as an alternative to conventional diesel fuel. It can be used on its own at 100 per cent strength or combined with diesel at 20 per cent.
Car owners can switch and alternate between using regular diesel and bio-diesel at any time with no ill effects on the performance of their vehicle. The use of EORC bio-diesel has recently been shown to result in 45 per cent less engine wear in a US study.
Bio-diesel entails no added maintenance costs, no extra charges or installation requirements. The sole recommendation to first time users is an initial filter change after 500 km since bio-diesel cleans sediment already present in fuel tanks which have been used for conventional fuel. Failing to buy bio-diesel from a reputable supplier whose product conforms to international standards may cause some problems.
In another presentation Keith Edwards showed how hybrid technology has been developed. Toyota has produced a car which combines a petrol engine with an electric motor for better fuel economy with significant reduction of exhaust emissions. The electric motor is used for slow speeds where petrol engines are least efficient.
When decelerating on a downhill slope or braking the electric motor generates electricity for storage in a high voltage battery. This combination is particularly suited for stop-and-go city driving as demonstrated by the Prius model. The car's air-conditioner runs off an electric motor allowing the cooling system to function even when the engine is turned off.
Treating sewage, capturing CO2
Process and design engineer at FM Environmental (Malta) Ltd, Ryan Falzon spoke on the advantages of a rotating biological contractor (RBC) over other aerated sewage treatment solutions. A number of rotating discs with micro-organisms alternate contact with waste water and air to biodegrade sewage within five days. The resulting water is of a quality suitable for sub-surface irrigation although further filtration (tertiary treatment) is necessary before use for flushing toilets, cleaning roads or suppression of dust. RBC uses very little energy and is practically maintenance free.
Combustion engineer Connie Ellul has worked with Enemalta on reducing and controlling emissions of carbon dioxide (CO2), nitrous oxide and soot. Ms Ellul gave her own view of the carbon abatement programme which is attracting interest worldwide as a means of bringing fossil fuel power generation plants into line with zero emissions. The capture and storage of CO2 may in future be integrated with basic structures of future power stations.
International projects are assessing the feasibility of storing captured CO2 in oil wells or aquifers to prevent it escaping to the atmosphere where it could cause a greenhouse effect, triggering climate change. On a global scale this technology could make a significant contribution to meeting the Kyoto Protocol, although it is unlikely that this technology will be resorted to in Malta. If worldwide energy demand continues to increase then it is feared that renewable energy sources may not be sufficient for meeting emission reduction ceilings.
Sant'Antnin upgrade
Engineer Pieter Morks, consultant to WasteServ, has been involved in the cleaning up of numerous ex-gas works, closed landfills and industrial complexes. He spoke on the transformation of Sant Antnin Recycling Plant into a modern waste processing and material recycling facility.
A landfill directive target must be adhered to by 2010 using the best available technology not entailing excessive cost and with the help of the EU cohesion funds. The plant must be designed to ensure that plastic bags are taken out mechanically as these lower the quality of the compost.
Malta's recovery rate of batteries from waste is still too low, resulting in hazardous material mixing with compost. Irrespective of how modernised the plant is, good quality compost can only be made if people co-operate.
"Don't expect to make good quality compost...," remarked Mr Morks in a reference to the composting of municipal waste at the plant "...it is nearly impossible." He conceded that the low grade compost produced would however make a useful cover material for the eventual rehabilitation of landfills.
Tipping of waste from collection vehicles is the point at which odours and aerosols are likely to be emitted. Referring to microscopic airborne particles known as aerosols, which often carry infection, he added, "Whatever people say they are dangerous." This hazard can be reduced and controlled by the use of suction areas and negative pressure in all waste handling areas. Contaminated air will be treated in a thermal oxidiser.
The explosive hazard present due to gases that would be produced by the digester was also noted. The risk is calculated to be equivalent to 12 domestic gas bottles. He spoke of the possibility of gasifying RDF (refuse derived fuel) as a measure to combat climate change. This fuel recovered from waste at pre-treatment stage is to be gasified or incinerated.
In a final comment to The Sunday Times he came clear about Malta's final solution in terms of the national waste strategy: "Incineration must only be used as the last resort," he concluded. Mr Morks added that between 2010 and 2013 a new facility has to be designed and brought into operation elsewhere in order to meet the new requirements of the Landfill Directive.
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