Green Electricty from Wind and Tidal Waves

Singapore team develops cost-effective renewable technology for power generation

Rapid economic development has ensured that the Southeast Asia (SEA) region is the key driver of growing world energy consumption. According to a report* by the International Energy Agency (IEA), over the next 20 years, the region's energy demands will grow at twice the global average.

This poses a challenge for the region's policy makers. SEA's energy demand has grown by more than 80 per cent since 2000 and the lion's share of this growth has been met by doubling the use of fossil fuel*. This has made air pollution a major risk to public health with energy-related carbon dioxide (CO2) emissions shooting up.

Despite favourable climatic conditions, renewable energy currently meets only around 15 per cent* of the region's energy needs. According to IEA, despite falling costs, the contribution of solar photovoltaics (PV), wind and marine remains small, though some markets are now putting in place frameworks to better support their deployment.

Wind and marine turbine energy generation offers many benefits to this region as a significant segment of SEA's population resides on remote islands where it is difficult to build large power plants and energy distribution systems. Renewable turbine generated electricity - both wind and marine - provide a compact and self-sustaining energy source for these remote locations.

Dr Narasimalu Srikanth, Senior Scientist and Programme Director at the Energy Research Institute @ NTU, shared a number of innovative solutions that his team has been developing in Singapore to meet the renewable energy requirements of the SEA region.

He was one of four technical experts speaking recently at IPI Singapore's TechExpert sharing sessions held during the SFFxSWITCH (Singapore Fintech Festival x Singapore Week of Innovation and Technology).

Dr Srikanth is part of the pool of experts from IPI's one-stop matching platform for the industry to engage with technical experts from diverse industry sectors for their innovation projects. Through the platform, enterprises can crowdsource and search for the right technical experts beyond their own network, and experts can discover new collaboration opportunities with the industry.

Renewable Energy Challenge

There are several challenges in setting up renewable energy generation systems in this region due to the specific characteristics of the wind and marine resources.

As an example, remote regions such as small islands have difficulty in erecting wind turbines which are resistant to natural calamities like typhoons that can strike suddenly. Also, due to geographical location, wind speeds during normal times is lower, at six to eight meters per second, in comparison to Europe, where wind turbines produce a significant amount of energy with an average wind speed of 12 meters per second.

Despite this, the small wind turbine market is picking up in the Asian region. There is a major need for technical expertise to design equipment that is best suited for the requirements of the region.

Sharing about his team's research and development (R&D) efforts in wind turbine technology, Dr Srikanth noted that his team optimised a design for an average eight meters per second wind speed.

The design incorporates a self-erecting mechanism so that the turbine blades can be lowered during typhoons to prevent their damage. In order to keep the cost down, cost effective materials and processes were used to build these turbines; for example, instead of the common two-piece composite moulding process for manufacturing the blades, a more affordable composite pultrusion method was used.

Dr Srikanth noted that scaling the initial design was a major problem. In many cases the materials used did not meet the scalability needs of mass production. There was also a need to plan for a "cradle to grave" approach to ensure full recyclability and minimum environmental footprint.

The team used computer aided engineering (CAE) to develop virtual prototypes and evaluate minimal viable product design through simulation. They also utilised scaled prototyping to undertake rigorous performance testing.

The final product by Dr Srikanth's team is a 10 kW (kilowatt) typhoon resistant wind turbine which was manufactured with local Singapore suppliers. His team has also designed and installed a vertical axis and horizontal axis wind turbine in Tuas with self-erecting capability. The turbines have been integrated into the nano-grid in Tuas which belongs to JTC. The project was supported by Singapore Economic Development Board's Energy Innovation Research Programme grant.

Tidal Turbine Systems

Another area of research for his team has been turbine systems which take advantage of tidal waves to generate electricity. One of the key advantages of using tidal power as a renewable energy source is that tidal cycles are predictable unlike wind or solar energy which depend to a large extent on weather conditions.

Dr Srikanth's research focus was to develop tidal turbine systems for tropical conditions specifically for energy needs for small islands and suit low flow tidal currents in region of around two meters per second with low wake length characteristics.

According to him, there is an enormous potential for energy extraction from four to six knots (speed) of tidal flow which is available along 80 per cent of coastlines. The challenge is how to economically, reliably and efficiently exploit low energy density flows and waves, Dr Srikanth said.

The other areas that need to be addressed are to maximise seabed real estate with least environmental disturbance, and to evolve and adopt suitable materials and fabrication technology. The team had to develop new products and concepts as the current European sea bed turbine systems are costly, at US$5000 to 8,000 per kW and they needed deep sea drivers for support and maintenance.

The solution developed is a towable and self-deployable system, which is seaweed resistant and optimised for low flow conditions. Energy storage integration was also built into the design. Dr Srikanth noted that ocean energy technology can meet the tropical coastal region's energy needs and is capable of supporting the three-fold challenge of energy security, CO2 emission reduction and economic and job growth, especially for remote island regions.

He added that collaborative effort is needed between technology developers, project developers, funding agencies and other key stakeholders in order to evaluate risks and mitigate them through early, full-scale test-bedding towards tropicalisation.