Award-winning Al-Bahr Tower in Dubai has an innovative shading mechanism.Life cycle analysis is a good eco-design tool for planners, designers and manufacturers. Renewable energy technologies have impacts that cannot be neglected during their life cycle. Payback time can be defined as the time needed to save as much energy as that consumed in the life cycle.
At the University’s Institute for Sustainable Energy (ISE) annual conference, Marco Beccali from Palermo University presented a case study assessing performance of a desiccant cooling system with applications in solar air-conditioning.
Two demonstration systems using silica gel are to be installed in Rome and Palermo with production expected to start by next year. Small systems more sensitive to correct sizing and operational strategy are expected to be costly. The study will help to decide which technology would be the right one to support.
Caroline Caruana, an architect and researcher on energy performance in buildings, has been looking at heat transfer in buildings with special reference to hollow blocks used in the construction industry. Measuring the thermal conductivity of concrete and working on improving heat flow through external walls could be one of the main ways to reduce energy consumption to heat and cool buildings, bringing them closer to net-zero energy by 2020.
Another Maltese architect has been involved in designing Abu Dhabi’s Al Bahr towers. Known as The Pineapple, this award-winning 30-storey twin block is wrapped in a dynamic skin – Mushrabiya style – to keep the sun off its clear glass façade. Structural engineer Konrad Xuereb showed how the system is operated by sun-tracking on glaring hot days, with the honeycomb exterior closing up if too windy.
Use of smokey glass, the norm for Saudi tower blocks, has turned out to be energy draining. Dark reflective facades require greater use of lights during daylight hours, resulting in higher energy consumption.
Policy options to upgrade existing Maltese housing was the topic addressed by the ISE’s Joseph Saliba, who suggested solutions to implement energy efficient policies. Maltese houses fall short of providing a comfortable environment all year round. Temperature in top-floor flats rise to over 30°C in summer and fall to 12°C in a ground-floor room over a garage in winter.
Insulation of rooftops is the best option. There are 60,000 rooftops where intervention is possible and a proposal for a financial instrument to make it happen has been formulated. A seven-year programme aims to help all dwellings acquire an energy performance certificate. Penalties would eventually apply if no certificate is in place for properties renovated, sold or rented.
Monitoring energy-related air pollution has become easier since a new instrument to gauge black carbon has became available recently, using an LED beam to measure carbon. So far, there are no standards for this pollutant, although the EU is suggesting a level of 18μg/m3 by 2020, while the World Health Organisation would like to see a limit set at nearly half that amount.
Double glazed windows, unless they are shaded, can make a room hotter
Black carbon is found in petrol (25 per cent) and diesel (75 per cent) exhaust, leading to an 18 per cent higher risk of heart disease. High levels were found in underground car parks and the Gozo ferry car deck.
Proposals for solar farms may not have to be restricted to rooftops and unused quarries as the sea is promising to be a new frontier for photovoltaic (PV) panels. The first systems to produce renewable energy on water, rather than take up agricultural land, were set up six years ago on lakes and reservoirs.
Panels at sea can float on the surface, lying flat or possibly rotating to track the sun. A project led by the institute will see the launch of the first prototype in the coming weeks, according to associate professor Luciano Mule Stagno.
An ISE study presented by Janis Muenchrath looked at integrating renewables and energy storage as Malta’s power sector moves from oil to gas. Various modelled scenarios take into account that the 25 per cent tariff cut is expected to somewhat increase demand for electricity. It is difficult to foresee the impact of the interconnector cable on costs.
Taking advantage of peaks in energy generation to pump seawater into holding areas, to release it to generate electricity when demand rises in Malta, or its price in Sicily is high, could be done by converting several quarries in southern Malta into a reservoir. Various other storage options have also been investigated to facilitate the integration of large renewable energy shares.
Making something as effective as possible requires both engineering and financial input. Should one go for the highest yield or lowest cost? The trend is to go for economic optimisation within a project’s lifetime. ISE optimisation studies are ongoing, with the latest results on a PV system presented at the conference.
Senior consulting engineer Timothy Ellis spoke about an Iowa State University study on bioenergy production. Anaerobic digestion should form part of a comprehensive plan for renewable energy.
Lisa Pace spoke about how firms go about becoming more energy efficient, seen from the viewpoint of innovation management studies. Her interest in transitions to low-carbon societies led to a study on how 17 local hotels interacted with 14 resource management firms.
Plans to renovate a legal office in Valletta presented an opportunity to improve energy efficiency in the building and tap renewable sources of energy. A survey was carried out as part of the Renewable Scenarios in Islands project, funded under the cross-border cooperation programme between Italy and Malta.
As part of the project, the ISE hosted a group of Sicilian students who conducted an energy efficiency study. During a walk-in audit, the students looked at the office’s computers, printers, lighting, heating, air-conditioning, appliances, building insulation and air circulation.
One culprit was found to be the hot and chilled water dispenser. This was found to be “a real energy gulper” in the words of ISE assistant lecturer Charles Yousif, whose advice was to “put a timer on it and switch it off at night”.
Installation of double glazed windows must be considered with great care as, unless they are shaded, they can make a room hotter. Micro-inverters and power optimisers render PV panels viable even when there is some shading on rooftops. More care must be taken as installation of PV systems in houses has led to over-consumption by complacent occupants. “If you don’t implement energy efficiency with renewables you can fall into this trap,” warned Yousif.
Cost modelling of floating wind farms with upscaled rotors in Maltese waters was the topic of a presentation by Matteo Aquilina. Offshore technology continues to develop, with a number of prototypes off the coasts of Norway, Portugal, the US and Japan. In one model, floating wind turbines with a diameter of 126 metres, 250 metres in height and an output of five megawatts were upscaled twice, subject to stability checks.
This example involved setting up 20 turbines off northwest Malta feeding a sub-station at Ġnejna Bay to distribute via Mosta. Shipping the giant components on a barge from north Germany to Sicily would require seven trips. The turbines would then have to be assembled in a Sicilian port, ballasted with sea water and towed on site.
Assessment of policy measures for Malta to reach its 2020 energy targets included a look at transport demand, which boils down to overall mileage. According to Alexander Lauri, we should promote the sale of new (cleaner) cars, promote car-sharing and teleworking. “It is critical to keep transport demand in check,” he said.
Other presentations covered development of a small-scale solar power installation with possible solutions for industrial processes (Bruno Kessler Foundation) and a look at the role of renewable energy in the Greek economy by Visiontask Development Consultants.
Some of the studies were the result of dissertations written as part of the ISE Master’s degree in Sustainable Energy programme. The course will open again in October.
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