Redesigning the exterior lighting as part of the urban landscape: The role of transgenic bioluminescent plants in mediterranean urban and suburban lighting environments

Abstract

This research discusses the feasibility of replacing or supporting artificial lighting with Transgenic Bioluminescent Plants (TBP), as a means of minimizing light pollution, reducing electrical energy consumption and de-carbonizing urban and suburban outdoor environments, creating sustainable conditions and enriching the quality of life. Until now, no information is given about the light output of any TBPs and the question “Are the TBPs capable of producing the necessary lighting levels for exterior lighting?” is unanswered. For this reason, a new methodology is proposed for selecting and analyzing the lighting output potential of transgenic plants ted for specific climatic conditions. This methodology considers growth and reduction factors, as well as a formulae for estimating the plants’ luminous output by performing light measurements. Results show that transgenic plants in medium growth can emit a median luminous flux of up to 57 lm, a value that can definitely support low lighting requirements when used in large numbers of plants. From the lighting measurements and calculations performed in this research, the light output of the TBPs for a typical road with 5m width was found equal to 2lx. The amount of plants required was 40 at each side of the road for every 30m of streets with P6 road class. The results show that the use of bioluminescent plants can actually contribute to the reduction of energy consumption, concerning only the lighting criterium, thus creating an enormous opportunity for a new state-of- the-art market and research that could potentially minimize CO₂ emissions and light pollution, improve urban and suburban microclimate, mitigate the effects of climate change, as well as provide an alternative means of lighting affecting both outdoor lighting design and landscape planning in suburban and urban settings. Moreover, further research should be applied considering also other possible ecological impacts before applying TBPs for exterior lighting applications.

Introduction

Over the last decades, the ever-increasing energy consumption has contributed to an accelerating man-made global warming, with detrimental effects on humans and ecosystems (IPCC, 2018). To reduce the pace of man-made global warming at cities (M. Santamouris, 2014), many countries have developed strategies to reduce greenhouse gas emissions from all sources including urban and suburban lighting. This includes lighting strategies focusing on energy efficiency (Doulos et al., 2019a, Jensen, 2017, Khorasanizadeh et al., 2016, Polzin, 2016), by cutting down energy consumption (Doulos et al., 2019b, Doulos et al., 2019c; (Zielinska-Dabkowska, 2013), increasing the albedo of cities (Santamouris, 2012), using cool materials (Doulos et al., 2004) expanding the green spaces in urban areas (Qun et al., 2019); (Mahyar Masoudi, 2019) (Dunnett and Kingsbury, 2008) and including eco-services within urban planning (Woodruff, 2016). The anticipation of urban green infrastructure planning and the regeneration of existing open spaces in the city, is the most necessary prerequisite for sustainable design, an among man and nature (Urban et al., 2019).

Artificial lighting is responsible for almost one fifth of the worldwide electricity consumption (Zissis, 2016). Specifically, in Europe, street lighting consumption corresponds to 1.6% of the total electricity consumption (Traverso et al., 2017). Even though street and exterior lighting in general prolong human activities (Beccalia et al., 2019) and promote the sense of security and safety (Peña-García et al., 2015), they are responsible for the irreversible transformation of the nightscape (Cucchiella et al., 2017), along with light pollution, which has severe consequences on animals, plants, as well as astronomical measurements (Hoelker et al., 2010); (Ngarambe et al., 2018); (Kocifaj, Solano-Lamphar and Videen, 2019). However, new artificial lighting technologies, not only reduce operational cost (Campisi et al., 2018) (Shahzad et al., 2018), but installation cost as well, since these technologies, such as LED luminaires, become cheaper in time. This has resulted in the emergence of additional usage of lighting, as well as the lighting of areas that were previously in the dark (Fouquet, 2006). This is confirmed by the data of the first-ever calibrated satellite radiometer, measuring night lights between 2012 and 2016, which showed that the Earth's artificially lit outdoor areas increased by 2.2% per year (total radiance growth of 1.8% per year (Kyba et al., 2017).

Another issue for consideration is the increased waste generated by the processing and manufacturing of light source components and the particularly demanding and energy-intensive process of recycling them, especially the recovery of Rare earth elements (REE) found in fluorescent lamps and LEDs (Machacek et al., 2015). The environmental impact of over-lighting and light pollution is growing, along with the increase of sky glow near human settlements and its becoming a serious threat to natural environments (Aube, 2013). In addition, LED lighting technologies have peaks in short wavelengths (blue part of the spectrum) that affect the health of living organisms (Brainard et al., 1996). In the context of saving electrical energy and promoting environmental sustainability, the use of artificial light sources in urban landscapes can be reduced or even eliminated in specific suburban areas by using the effects of bioluminescence through transgenic plants. However, there are might be other factors that should be taken into account were might blocking the overall benefit (Rodríguez et al., 2019).

Systematic research on the light production of bio-luminescent systems, along with the classification of the respective organisms, has been already recorded between 1500 and 1700 AD (Roda, 2011), while researching the light-producing mechanism itself was completed later in the middle of the last century (Herring, 2000) (Nakamura and Haneda, 1966, Strehler and Arnold, 1951). Bioluminescent plants exist only in marine algae (Monocyte) and micro-organisms (Dinoflagellates) (Valiadi, 2013), as well as some types of Fungi, which are simplified plant forms lacking chlorophyll (Shimomura, 1992).

The production of bio-luminescence in laboratories and especially the expression of bioluminescence in plants has been studied by numerous scientists during the 20th century. Landmarks in the research of the production of bio-luminescent properties can be summarized as follows:

• The chemical synthesis of Luciferin from fireflies carried out by Jacobs in Johns Hopkins University - (Jacobs, 1974); (Lonsdale et al., 1998); (Barnes, 1990),

• Βioluminescence through Luciferin, Luciferase and Oxygen peroxide from marine organisms by Cormier and Kishi- (Cormier M.J. 1965); (Kishi et al., 1965)-,

• Synthesizing the Luciferace enzyme from fireflies to produce a luminescent tobacco gene by Marlene De Luca et al. (DeLuca et al., 1986),

• The isolation of Luciferase from marine photobacteria (V. Harvey Fisheri and Phosphoreum) by Koncz C.L., Mc Elroy - (C. L. Koncz et al., 1990) (McElroy 1944);- and

• The creation of nanobionic luminescent plants by M.I.T University and (Kwak et al., 2017).

While there is ongoing research for the development of the Transgenic Bioluminescent Plants (TBP) (Branchini et al., 1999, Cazzonelli and Velten, 2006, Charrier et al., 2010, Czyz et al., 2000, Grajkowski, 2016, Hummer and Hancock, 2015, Koksarov and Ugarova, 2008, Koncz et al., 1990a, Koncz et al., 1990b, Kondo et al., 2002, Malnoy et al., 2010, Meighen, 1993, Mitcell et al., 2005, Nass and Scheel, 2001, Parvez et al., 2005, Phiefer et al., 1999, Sarris, 2004, Schneider et al., 1990, Thouand et al., 2003, Vamlig, 2007) and the examination of any ecological impacts from their use, as presented, there is a gap concerning the amount of the emitted light output, the compliance with norms (EN, 2014, EN 13201, 2015) with regards the lighting levels, the number of the TBPs needed for compliance with the corresponding lighting levels, and finally if their selection is applicable for lighting urban or suburban areas. Due to lack of photometric data in the literature on the yield of TBPs, this research aims at two interconnected targets: a) to calculate the light output of a selected transgenic bioluminescent plant and b) to simulate the lighting distribution and levels, so that the results can be used to calculate the necessary number of plants required to supplement, or replace, artificial lighting in a specific outdoor environment. The research was focused on eastern Mediterranean suburban landscapes and their planning, due to the fact that several plants that have been genetically mapped and can be modified to accept bioluminescent properties, thrive in the Eastern Mediterranean. These objectives are a prerequisite for evaluating the proposed replacement of artificial lighting in open spaces and drawing a conclusion on its viability and feasibility. For this reason, experiments were made, in order to identify the potential luminosity that Vibrio Fisheri bacteria can achieve and a comparison was made between the most efficient outdoor lighting and the proposed TBPs. Furthermore, the identification whether TBPs can be an option for illuminating exterior areas or not, can provide a basis in order to activate the respective research teams so that they investigate their ecological impacts.

The structure of the paper consists of a methodology section, where the steps taken are discussed in detail. Specifically, issues discussed in the methodology include the selection of suitable plants for genetic transformation and the development of a reduction factor based on the plant properties. The next section contains the measurements and calculations of the projected plant foliage, the calculations and measurements of light intensity and luminous flux and finally the creation of a luminous profile to be used in lighting calculations. The following section presents the results, that present the luminous flux of the plant in comparison with a LED streetlight. A discussion follows the structure of the paper, concerning specific issues on this research and finally the conclusions.