Team:SJTang/Implementation

Biohydrogen production is not only restricted in laboratories, but is also open to a range of applications in the form of fuel batteries, ranging from industrial use to products in daily lives. When taking the production and efficiency into consideration, we chose upon LED warning board to apply with. In rural areas with debris flow, uneven mountain or avalanche, natural disasters which are threatening to life commonly occurs. Therefore, it is necessary to put up signs in order to warn people of danger. However, during times of rain or night, the signs are usually hard to notice. When people are thinking about using LED to light up the signs, nevertheless, it is not possible to pull wires over such areas due to the remoteness or environment.
In this case, biofuel batteries become a desired alternative for the governments at remote areas, or non-government organisations dedicated to ensure the safety of people living in rural areas. Biohydrogen fuel batteries does not have to take lots of extra resources, and only needs periodic nutrients supply. Users can place the battery at the sign, and fill the nutrients supply weekly. The sign can light up in the night every day and become a long-lasting design. This session is going to discuss upon the feasibility of this implementation.

In order to provide an applicable approach, the sign must follow the standard requirements. In China, they are distributed accordingly to their purposes and types. As the signs of warning and remaindering fit the application of rural places that are dangerous, these two types of signs are typically discussed in the following. According to China’s Safety signs and guideline for the use GB2894-2020 [1], the size requirements of the signs are listed as below. L stands for the observation distance, which is shown below in the chart. For warning signs, the outer side a1 = 0.034L; the inner side a2 = 0.700a1, and the radius of the outer corner of the frame is r = 0.080a2. For indicator signs, the side length, a=0.025L, as shown below.

Figure.1Road sign specifications outlined by GB/T 31446-2015.

According to LED active light-emitting road traffic signs GB/T 31446-2015 [2], The signs need to use light metal or non-metallic materials. The color of the active light-emitting unit of the warning sign is yellow; whereas the color of the active light-emitting unit of the indicator is white. The normal luminous intensity of a single LED at rated current is that yellow is no less than 3000mcd, and white is no less than 6000mcd. The non-uniformity of the normal luminous intensity between the pixels of the active light-emitting unit of the same color should not be greater than 10%. Also, the light-emitting sign products with dimming function should have an environmental illuminance detection device, and can automatically adjust the luminous brightness of the sign according to the environmental illuminance to avoid glare when the environmental brightness is low. In addition, the geometric size of the light-emitting surface of the active light-emitting unit should not be less than 5mm, and the pixel center spacing should not be greater than 35mm. The pixel center spacing of the active light-emitting unit that is only used to display outlines and does not transmit specific logo information content should not be greater than 40mm.

This minimum cost of $0.37 of a warning sign, and $0.52 of a indicator sign per day is higher than the price, $0.23 and $0.32 cost respectively by the fuel cells to operate and light up the signs. For the higher cost than the normal hydrogen fuel cells, this is likely to be improved for biohydrogen fuel cells. For future improvements, the bacteria may be genetically modified to produce hydrogen at a higher efficiency, the bioreactor may be designed to be more efficient, and the nutrients may be supply modified to use agricultural food or animal wastes, in order to lower the daily cost of the signs. For some fuel cells, for example, those using electrolysis, although it appears to be a clean method, a lot of energy is demanded. If the energy is derived from fossil-based ways, the process is still not carbon-neutral[9]. As biohydrogen fuel cells, it is environmentally friendly and uses nutrients, including wastes, as the energy source.

This current price of the biohydrogen fuel cell method is more expensive than the conventional means of electricity and fluorescent signs. However, as mentioned before, the biofuel cell of hydrogen has is relative benefits. Compared to fluorescent signs, biohydrogen fuel cell is can make the sign far brighter, and can carry out its goal of preventing people from danger pretty well. Compared to other means of normal ways of electricity, it does not require electrical wire, thus avoiding visual harms to the environment. It can light in remote places, being able to warn people of danger. It can be powered by adding nutrients, and thus it is its sole long-term expenditure. Furthermore, it works out for the betterment of the environment. It totally uses clean energy, and thus avoids all the bad impacts to the environment. It is rather worthy to spend money on the betterment of the environment. Thus, it is within a relatively acceptable range, and is thus generally applicable.

However, there are still challenges in operation and economically. In fermentation that requires light, it can be obtained from the sunlight at daytime. However, if the weather is rainy or gloomy, sunlight is considerably reduced, thus limiting the production of hydrogen, and thus energy supplied. Thus, the implementation carries a problem that it is not so stable in operation, and certain weather factors may interfere with the operation process. Also, the cost is still larger than that of conventional fuel cells. This imposes an economic concern such that the compatibility of biohydrogen fuel cells may be challenged as it requires more cost. In order to lower the cost, more cost-effective materials may be used, for example, agricultural food, livestock, and reused oil. This lowers the daily cost of nutrients, but at the same time, may have some cost to process these resources. Also, additional costs may be put at the operation of anaerobic equipment that provides a rather tight seal for R. Palustris. Therefore, there exist economical challenge to the compatibility and ways of lowering cost.

For biohydrogen fuel cells, we need to take the safety into consideration. Hydrogen can be explosive when put together with oxygen, giving a considerable hazard. It can form combustible mixtures at concentrations of 4.0%–75% [10]. Under this circumstance, hydrogen may explode when get in touched with flame. Also, if hydrogen is leaked out in closed areas, it may build up, displace oxygen, and cause asphyxiation. Thus, it is be required to have an airtight storage of the production for hydrogen in order to avoid leakage, which may push potential dangers. For further safety concerns, safety relief devices or venting pipe may be arranged at the hydrogen storage component to discharge upward the gas in case of leakage[11], in order get the concentration within the safe limit may be taken right afterwards. Also, a device detecting the leak of hydrogen may be placed, call for emergency if there is a leak, to warn people to get away from the sign, and call for other safety processing if necessary.

Therefore, the hydrogen produced may be implemented to biohydrogen cells, which is aimed at users of government in remote areas, or non-government organisations dedicated to protecting people from danger. The cell may have its nutrients supply of glycogen may be filled weekly, in order to light up the sign at the night, enabling people to notice it easier and step away from danger. Although the cost of operating is currently higher than that of traditional ways of electricity generation, it has the advantage over which that it produces no harmful substances and effectively prevents any harm to the environment.

References:
[1] China's National Standardization Management Committee. (2020). Safety signs and guideline for the use GB2894-2020. Retrieved October 19, 2021,
[2] China's National Standardization Management Committee. (2018). LED active light-emitting road traffic signs GB/T 31446-2015. Retrieved October 19, 2021,
[3] JiaLeTu LED. (n.d.). Imported chip brightness high-power led lamp beads 1W3 watt warm white red, green and yellow light spotlight light source light bulb.
[4] Essom.co. (n.d.). Heating values of hydrogen and fuels..
[5] Haseli, Y. (2018). Maximum conversion efficiency of hydrogen fuel cells. International Journal of Hydrogen Energy.
[6] Maru, B. T., López, F., Kengen, S. W. M., Constantí, M., & Medina, F. (2016). Dark fermentative hydrogen and ethanol production from biodiesel waste glycerol using a co-culture of escherichia coli and Enterobacter sp.. Fuel. Elsevier..
[7] Baovi Energy Technology. (n.d.). Food grade refined vegetables glycerine 99.7% glycerol. Alibaba.
[8] Fuel cell costs. Fuel Cell Guide - Fuel Cell Costs. (n.d.).
[9] Cagalitan, D. D. T. F.-D., & Abundo, M. L. S. (2021, July 28). A review of biohydrogen production technology for application towards hydrogen fuel cells. Renewable and Sustainable Energy Reviews.
[10] Dagdougui, H., Sacile, R., Bersani, C., & Ouammi, A. (2018). Hydrogen infrastructure for Energy Applications. ScienceDirect.
[11] Rivkin, C., Burgess, R., & Buttner, W. (2015). Hydrogen Technologies Safety Guide - NREL. National Renewable Energy Laboratory.