SLINTEC Building Structure 1500x110-04

Renewable Energy

Renewable energy is harnessed from natural resources such as hydro, wind, wave, solar and geothermal heat and combustible renewables and renewable waste such as landfill gas, waste incineration, solid biomass and liquid biofuels [1]. Traditionally, fossil fuels have been the source of power generation. However, renewable energy technology adaptation for power generation has increased across developed and emerging economies throughout the past decades and is expected to grow in the foreseeable future. Renewable energy is used for electricity generation, transportation, heating/cooling and off-grid energy services replacing fossil fuels [2]. As of 2020, renewable energy provided an estimated 29% of global final energy consumption [2]. Rapid growth of renewable energy is mainly due to energy security, climate change mitigation and resource availability [2]. Public opinion has changed in favour of renewable energy in the past decades with scientific literature supporting fossil fuel induced global warming [3].

Attributed to geo-climatic settings, Sri Lanka is blessed with renewable energy resources. In 2017, fossil fuels including coal accounted for 54% of the Sri Lankan energy mix [9]. Renewable sources accounted for 9%, with biomass generating 37% [9]. This has not changes much since then up to now. As an island nation, Sri Lanka is particularly vulnerable to rising sea levels caused by climate change. Sri Lanka is one of 43 countries in the Climate Vulnerable Forum, the members of which are committed to reaching 100% renewable energy generation by 2050 at the latest [4]. Sri Lanka has set a futuristic and progressive task of increasing its share of renewable energy in electricity generation to 50% by 2030 [5]. 

The Sri Lankan advantage

Sri Lanka Sustainable Energy Authority (SLSEA) is the apex institution overseeing RE [5]. Sri Lanka is the 39th greenest country in the world, in terms of RE share in power generation [5]. Public power-generating program ‘Surya Bala Sangramaya’ (SBS) was also initiated recently by the government to encourage solar power [5].Two thirds of the country’s lowland area receives solar radiation. Solar radiation is a variable resource, however, a substantial potential exists in the dry zone of Sri Lanka for harnessing solar energy. The commercial capabilities of solar-power plant Hambanthota Buruthakanda Solar park operated by SLSEA needs to be fully exploited [8].

It is estimated that there is nearly 5000 square kilometer of wind area in West Coast, Mannar, North West Central High- land, South East and North Eastern areas with good-to- excellent wind resource potential in Sri Lanka [10]. Monsoonal winds could be harnessed throughout the year. Potential of all promising wind sites in Sri Lanka is about 25,000MW [10]. The first commercial grid- connected wind farm is the 3MW Hambantota Wind Farm [8].

With a rain fed central hills, Sri Lanka enjoys good hydro power potential. Currently, ten large hydroelectric power stations are in operation. Although a large portion of the country’s hydroelectric resource is tapped, the government continues to issue small hydro development permits to the private sector, for projects up to a total installed capacity of 10 MW per project [8].

Geothermal power generation is under re-search, several areas in Eastern and Southern province have been identified, although no power stations of this type is operational as yet.

Sri Lanka has a potential of producing biomass (i.e. Gliricidia sepium) as a result of high plant growth rate due to high incidence of solar energy, soil conditions and rainfall. It is estimated that approximately 40 Billion kg of biomass can be generated by converting marginal land to fuel wood plantations, and improving productivity of other crop land and home gardens according to Energy Conservation Fund.

There is lack of serious debate over RE being used for transportation (which is heavily dependent upon fossil fuel) in Sri Lanka. Ethanol can be distilled from Sugar- cane by products and could be used as a blend with  Petrol as Gasohol (i.e. Brazil) to alleviate fossil fuel dependency. Cellulosic ethanol from various plant sources promises replacement of fossil fuels. Therefore, the potential in biofuel from biomass is immense.

EMERGING TECHNOLOGIES

Research and development is being done worldwide on renewable energy technologies especially in China, US, Israel and Europe. Research on Tidal energy, cellulosic ethanol and geothermal power is being done for electricity generation, transport and heating respectively.

Solar Glass

Solar glass is a transparent glass panel capable of harvesting solar energy. Solar glass uses organic salts to absorb ultraviolet and infrared light unlike other photovoltaic cells that absorb photons [13]. After the salts absorb the non-visible wavelengths, they produce infrared light that is pushed to the panels’ edges, where strips of conventional photovoltaic cells convert it to energy. This technology, pioneered by Ubiquitous Energy, is made of low-cost materials, making mass production and adoption much easier. Pilot project activities are underway [13].

A group of MIT scientists found a new technique involving coating glass with a specific mixture of transparent dyes which redirect light to photovoltaic cells in the frame thus converting to energy [16]. This technology could be used in windows (in high rise buildings) and cell phone panels to capture solar energy [13].

Waste to Energy

UK-based Advanced Plasma Power has developed a technology that uses waste including non-recyclable household and commercial/ industrial waste to energy [13]. A two-stage advanced process converts the waste into two outputs: an energy-rich synthesis gas and a solid product that Advanced Plasma Power calls Plasmarok [13]. “The gas can be used to power engines and turbines; it also provides a plentiful source of hydrogen, which could supply hydrogen fuel cells. Additional products include heat, substitute natural gas, and liquid fuels. The solid byproduct could be used as a construction material, as its low leaching property is environmentally friendly”. US-based Fiberight is also piloting a waste-to-energy model that uses municipal solid waste and other organic waste to produce renewable biofuels [13]. Sweden, Japan and South Korea have similar plants that generate energy via solid waste management.

Tidal turbines

 A form of hydropower that generates electricity. Currently used in small scale, with the potential for expansion. This energy encompasses both wave power – power from surface waves and tidal power obtained from the kinetic energy of large bodies of moving water [15]. Reverse electro dialysis (RED) is another technology for generating electricity by mixing fresh river water and salty sea water in large power cells generating electricity [15]. Rance Tidal Power Station in France and Sihwa Power Station in South Korea uses tidal turbine technology (tide and undercurrent) in electricity generation.

Biofuels

Various microalgae grown in open or closed systems are being tried in Hawaii by Global Algae Innovations [17]. Alga culture (farming algae) for making biodiesel and other biofuels using land unsuitable for agriculture is being considered. Alga can be grown with minimal impact on fresh water resources and are biodegradable. The United States Department of Energy estimates that algae fuel can replace all the petroleum fuel in United States if developed [17]. Ethanol distilled can be used in its pure form or mixed with Petrol can be used in vehicles. This product or Gasohol (as it is called in Brazil) is used in Brazil (from sugarcane byproducts). New technologies are emerging involving genetic modification of alga to produce new fuels especially hydrogen from highly efficient algae and production of energy [18]. “Cellulose, which provides the cellular structure for all plants, is the world’s most abundant organic compound” [19]. Several refineries that can process cellulose biomass and turn it into ethanol are built by companies such as POET. Other companies such as Novozymes are in the process of producing enzymes for mass degradation of biomass thus making feedstock for biofuel [20]. However, Biofuel from Corn (Maize) has been in use for decades in the US.

An enhanced geothermal system (EGS)

EGS generates geothermal electricity without the need for natural convective hydrothermal resources. “EGS inject water at high pressure into deep rocks to re-open the natural fractures and allow hot water or steam to flow into extraction wells” [22]. Continuous injection keeps these fractures open and provides a constant source of water to be heated up and extracted for electricity production [22]. Until recently, geothermal power systems have exploited only hot springs/geysers type re- sources where naturally occurring heat allows energy extraction (Iceland).

Floating solar arrays

Floating solar arrays are PV systems that float on the surface of water bodies such as dam reservoirs and oceans. A small number of such systems exist in Japan, South Korea, United Kingdom, France, Indonesia Singapore and the United States [22]. Floating solar panels are attached to interconnected, plastic rafts that allow them to stay on top of the water [22]. Floating systems may also perform better due to cooling by evaporating water, which causes them to operate more efficiently [22]. According to a study by Korea Water Resources Corporation, a floating array could be 11% more productive than land-based systems [22]. Only disadvantage is that the body of water should be calm and still. 

Concentrated Solar Power

Concentrating solar power plants generate electricity by converting the sun’s energy into high-temperature heat using mirrors [23]. The heat is then channelled through a generator [23]. The plants consist of two parts: one that collects solar energy and converts it to heat, and another that converts heat energy to electricity [23]. This technology has been used by Spain extensively. Some systems use thermal storage during cloudy periods or at night and others can be combined with natural gas and the resulting hybrid power plants provide high-value, dispatchable power [23].

Hydrogen as fuel

Hydrogen can be separated from hydrocarbons by heating, a process known as reforming. An electrical current can be used to split water into its components of oxygen and hydrogen, the process is known as electrolysis [24]. Some algae and bacteria, using sunlight as their energy source, gives off hydrogen [24]. Hydrogen is highly flammable (i.e, Hindenburg airship disaster). An engine that burns pure hydrogen produces only water and Oxygen. “NASA has used liquid hydrogen since the 1970’s to propel the space shuttle and other rockets into space” [24]. Hydrogen fuel cells also powered the shuttle’s electrical systems, producing pure water, which the crew drank [24]. “Fuel cells are a promising technology for use as a source of heat and electricity for buildings, and as an electrical power source for electric motors propelling vehicles” [24]. Lawrence Berkeley National Laboratory (Berkeley Lab), Department of Energy (DOE), US have discovered a new material called air-stable magnesium nano-composites which can help in storing hydrogen without complex methodology [25]. This composite material consists of ‘nano-particles of magnesium metal sprinkled through a matrix of polymethyl methacrylate–a polymer related to Plexiglas’ [25] This nano-composite is a pliable material and it is capable of absorbing and releasing hydrogen at an ordinary temperature without oxidizing the metal [25].

Toyota’s futuristic vision of the Hydrogen powered vehicle [26]

SLINTEC’S VALUE PROPOSITION

Fossil fuel induced global warming leading to climate change and energy security has become a major concern affecting the whole world today. Increasing population growth, urbanization and the subsequent increase in consumption has led to the requirement of power for electricity generation, transport (mobility) and heating.

Renewable Energy (RE) is poised to grow and most states have set targets to achieve 100% RE usage and reduction of fossil fuel to combat global warming. However at present, fossil fuel is used as the primary energy source. It would be the cities that would generate RE in the future with potential in Solar and Wind for electricity generation and Hydrogen fuel for transportation.

Majority of the developed and developing states have pioneered the use of renewable energy technologies and China is driving the future of renewable energy generation. However, the pressing issue of transport remains at large. Bioethanol and Hydrogen fuel has become the emerging technologies in transport with potential replacing fossil fuels especially in the global context. Also, renewable energy storage devices and battery technology are in need. Tesla Inc.’s has taken the initiative in RE automobiles and RE storage systems for household use. 

Sri Lanka has abundant natural resources of solar wind and hydro energy. There is also potential in geothermal energy for further development. 100% renewable energy supply is technically possible, with transport considered the most challenging sector. Mini hydro plants, solar and wind farms in the dry zone, energy from solid waste feedstock and bio ethanol (for transport) is the way forward. Time is opportune to find an alternative to fossil fuel in the transport sector and power generation. 

Drawback of wind and solar energy utilization is the mismatch between the peak supply and peak demand curves, resulting in volatility, lack of base capacity and inefficiency of the power supply. The solution to the above is development of renewable energy storage systems, which Sri Lanka does not currently possess. Battery technology could be the solution where SLINTEC expertise lie. 

SLINTEC’s advanced material research expertise and laboratories equipped with state-of-the-art instruments suited for R & D on identification and development of renewable energy storage device technologies such as batteries. SLINTEC expertise in graphitic material such as graphene can be used for increasing surface area of batteries thus enhancing capacity.

Author- Ravinda Soysa , Graphics – Lahiru Ranathunga

References

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