Product Development & Manufacturing
The reduction of greenhouse gas emissions (GHG) has become a common world-wide goal in response to the impacts of climate change and increasing global warming affecting numerous societies, ecosystems and wild-life. Implementation of LED lighting has been attempted to reduce GHG, however it is a very costly approach. We therefore developed the LIT Bulb, an efficient, sustainable, eco-friendly, long-term and cheap solution for public illumination that requires a minimal electricity/nutrient input
Our LIT bulb is powered by the co-culture of Cyanobacteria and E. coli cells. Both cell types have been programmed to symbiotically coexist and produce enough luminescence to light up a street on a nightly basis. E. coli will detect sunlight levels and luminesce only during night time to promote an efficient and long lasting luminescence during the period of darkness. Cyanobacteria will be engineered to secrete the sucrose product from photosynthesis to feed E. coli for their long-term survival.
How the LIT Bulb works
When sunlight is present, the biological switches in our cells become repressed and proteins involved in the production of luminescence will not be produced. Oppositely, during the evening when light is not present, our biological switches become activated and luminescence is produced. As such, the LIT bulb is fully automated. Additionally, this ensures that the toxic build-up level of these proteins is avoided. We are also using photosynthetic Cyanobacteria cells (Synechococcus elongatus PCC 7942), which are engineered to secrete sucrose as an energy source and long-term survival of our E.coli cells. E.coli respiration will also contribute to CO2 production that can be used by Cyanobacteria for their photosynthesis. We then created a unique LIT bulb design which allowed for uniform lighting while at the same time maintained the correct conditions needed for the continued survival of the two cell types.
Our original idea was to create genetically engineered cells that would not require any electrical or mechanical input to keep cells suspended in a culture. However, we soon realised we would be facing homogeneity issues due to heat and nutrient transfer if we did not come up with a design that could continuously re-suspend our cells inside our lightbulb. So we invented a design that incorporates a rotor that gently moves the cell cultures around such that they are always in correct suspension and equilibrium. We also considered the high energy strain of the cells due to luminescence production, temporary/limited food source, robustness/safety/biocontainment, permeability to oxygen (gas exchange) and human perception.
Figure 1: Components of the LIT bulb designd with Pictochart
We developed mathematical models to determine the optimal dimensions of the light bulb as well as the quantities of each microorganism required to provide the maximum amount of luminescence possible (160W). The circular structure of the LIT bulb maximizes the exposure of Cyanobacteria to sunlight. We introduced a pump to ensure the cells remain suspended and the cell culture is homogeneously distributed throughout the LIT bulb. We also added a three-way manual valve to allow for the easy replacement of media once every 12 months. We will add a filter to the valve to allow media to be replaced without removing the cell culture. To validate the robustness of our product we would conduct a series of experiments to optimise the shape and components of the LIT bulb using the data we have obtained from our OptoFlux design model. The LIT bulb has been designed such that it fits inside the conventional streetlamps in London.
We also considered 6 criteria in order to assess the credibility and applicability of our light bulb with regards to currently used street light technologies. The table below compares these criteria across conventional light bulbs, LED light bulbs, light bulbs with motion sensors and our LIT Bulb. As shown in the table below, our technology has the potential to revolutionise street lighting in London. The most attractive component of our light bulb is the positive environmental impact that it represents.
Figure 2: Summary table of the six major criteria evaluated for all Streetlight technologies
A single incandenscent light bulb consumes 3000kWh of electricity over a period of 50,000 hours and produces 185kg of CO2 emissions yearly . A single LED bulb uses 400kWh and produces 70kg of CO2 emissions yearly . Our LIT Bulb will reduce this values to 34kWh usage and only 2kg of CO2 emissions yearly as it only uses a pump that requires 1.8watts of electricity.
The above calculation was determined with the fact that one bioluminescent bacterium produces about 1000 to 10,000 (103 to 104) photons per second . 1014 luminescent cells contained in our LIT Bulb would produce the light output of a 160-watt bulb (a 100-watt light bulb emits 1018 photons per second) . Therefore the only electricity requirement to emit 160-watts is the power consumption of the pump, which consists of 1.8watts. Thus to produce 60watts of light we require 0.675 watts of power [(60watts x 1.8watts) / 160watts] = 0.675watts.
Lighting alone consumes 19% of global electricity and electricity is the largest contributor to greenhouse gas emission, accounting for 25% of global carbon emissions. In the UK (2005), street lighting was using approximately 3.14 TWH of electricity giving rise to CO2 emissions of 1.32 megatons. We are addressing this environmental impact with the use of synthetic biology, a cheap and eco-friendly alternative to electricity powered lighting technologies.
- √ Lower CO2emissions
- √ Low maintenance Costs
- √ cGMP guarenteed
We decided to approach the development of our LIT bulb by adopting the the conventionally used engineering design cycle, as it perfectly reflects the design of our LIT bulb. We want to constantly update, improve and adapt the LIT bulb to technological progress, changes in the market and new policies.
The final LIT Bulb design aims to provide a long-term stable light source. We plan to engineer E. coli cells to bioluminesce only at night time to minimise the energy strain of bioluminescence production, and to engineer cyanobacteria to perform their natural photosynthesis but secrete the glucose product to feed the E. coli cells for their long-term survival. The oxygenic photosynthesis by the Cyanobacteria will simultaneously reduce the amount of carbon dioxide in the atmosphere. Our aim is to create organisms that can only reproduce and survive under artificial conditions. To do this, we envision running our own experiments which will be aimed at evaluating which bacterial strains grow solely in the presence of very low levels of specific gases, namely Oxygen gas. We would also test our LIT bulb under extreme environmental conditions to ensure that luminescence would be produced by our bacteria under the harshest of environments.
The future of the LIT bulbs
We decided to envision the implementation of our product, the LIT bulb, using a “think global, act local” approach. We examined and quantified the economic, social and ecological advantages the application of the LIT bulb would have in the U.K. and extrapolated these results onto the world. We also worked on tweaking our original idea to include a further safety measure that could assuage public concerns about leakage of genetically modified organisms into the surroundings. Our long-term future thinking includes making LIT bulbs that can be used for lighting billboards, gardens and outdoor venues.