1. Introduction

2. Methodology

3. Value/ Originality

4. Algae and Its Versatile Role in Sustainability and Energy Production

4.2. Algae Classification and Life Cycle

Algae are plant-like organisms that are subdivided into two categories: aquatic and photosynthetic. Although they are plant-like organisms, they lack true leaves, roots, stems, and vascular tissue but possess simple reproductive structures [12].

Organisms that have only one set of chromosomes are called haploid, often noted as “n.”. Diploid organisms have two sets of chromosomes, one from each parent, and “2n” is used for this stage [13].

Algae lifecycles vary depending on species; there are four different patterns, and all four patterns in the algae lifecycle alternate across generations: haplontic, diplohaplontic, and triphasic [14].

There are diploid stages and distinct haploid stages, and, in all cases, the haploid stage is called the gametophyte, and the diploid stage is called the sporophyte.

These algae convert carbon dioxide and sunlight into heat, oxygen, and biomass. The integration of microalgae, as a photobioreactor-based source of biofuel, with buildings has the prospect to alter high-performance architecture [15]. However, big challenges need to be considered concerning the requirements relating to CO2, storing systems, and maintenance.

Figure 1. Lifecycle of algae [13].

Figure 1. Lifecycle of algae [13].

4.5. Cultivation Methods

A variety of methods can be utilized to cultivate algae, including open pond, fermentation, hybrid, and closed photobioreactor methods.

Open pond: Only needing a pond, an open pond system is much less expensive compared to other cultivation systems. It also retains a large production capacity. Another merit is its simplicity and low production and operation costs. However, such systems can only support one type of algae due to the fact that different species of algae require different conditions to prosper; an open pond system cannot offer this variety of conditions [4]. While readily available, this method requires vast open spaces. These systems are also susceptible to contamination and the growth of undesired species, CO2 diffusion, loss of water due to the open environment, and the risk of reduced sunlight exposure.

Fermentation: This method requires laboratory conditions and bulky reactors, making it impractical for integration into existing buildings despite its scalability potential.

Closed photobioreactors (PBRs): This method is the most promising option due to its controlled environment, which mitigates the limitations associated with other methods. PBRs enable optimal mixing, even the distribution of CO2 and O2, and flexible light utilization (artificial or daylight). Moreover, they facilitate the cultivation of a wider range of species across extended growth periods owing to temperature control [17].

Table 1. Different types of algae cultivation systems with descriptions [4].

Table 1. Different types of algae cultivation systems with descriptions [4].

5. Algae Building Technology (ABT)

Figure 2. A schematic elucidating the inputs and outputs of an algae-powered building and their use [20].

Figure 2. A schematic elucidating the inputs and outputs of an algae-powered building and their use [20].

5.1. Algae-Powered Buildings

The BIQ building stands as the first real-world application of a building powered by algae. Its design integrates flat plate photobioreactors (PBRs), a novel element added to the architecture of the BIQ aimed at generating heat and biofuel, thus striving toward self-sustainability by fulfilling the building’s energy needs through algae cultivation. Publicly introduced as the “Solar Leaf” bioreactor façade, this innovative system, devised by Arup and Colt, represents a cutting-edge technology in the cultivation of microalgae on building exteriors to produce heat and biomass as renewable energy sources, drawing inspiration from photosynthesis for energy-efficient designs. This five-story residential structure hosts microalgae PBR façades on its southeastern and southwestern sides and is equipped with a comprehensive infrastructure to support its operations, including CO2 and nutrient supplies; biomass filtering and harvesting mechanisms; temperature and circulation control; and heat harvesting, storage, and distribution systems. Additionally, the harvested algae biomass is transported to a biogas plant for processing prior to subsequent utilization in energy production [1]. Featuring 129 PBR panels, each measuring 2.5 m × 0.7 m with a thickness of 0.08 m and a liquid capacity of 24 liters for microalgae culture, the system operates autonomously, thus diminishing maintenance costs. These aforementioned PBRs have the capacity to produce 150 kWh/m2 of thermal energy and 30 kWh/m2 of bioenergy. The energy demand of the building was successfully reduced by 50%, and with the intended use of solar panels to sustainably meet the operating energy needs of the PBRs, this value could become 100% [20]. By virtue of its dual processes of converting light into heat and biomass, the system has achieved an impressive overall conversion efficiency of 58%, with 10% attributable to biogas and 48% to heat, showcasing its potential as a sustainable energy solution [1]. A symbiosis relationship was built between the 200 m2 PBR façade and the outdoor gas plant, where the supply of CO2 introduced to the system comes from flue gas emanating from the gas burner while rendering the algae into biomass. The PBRs are capable of sequestering approximately six tons of CO2 yearly [10].

Figure 3. On the left, a photo of the BIQ building and its flat plate PBR [9]. On the right, a schematic showing the flow of bioenergy and biomass production [1].

Figure 3. On the left, a photo of the BIQ building and its flat plate PBR [9]. On the right, a schematic showing the flow of bioenergy and biomass production [1].

The Green Loop Tower represents an innovative approach to sustainable development that strives to upgrade existing building structures with environmentally friendly technologies. Per the Chicago Climate Action Plan’s goal of lessening GHG emissions by 80% from 1990 levels by 2050, this initiative exploits various sustainable solutions to achieve a net-zero carbon footprint [10]. The marina towers are good examples of existing buildings that can be retrofitted into greener buildings. Influx Studio came up with this project in 2011. They devised a cutting-edge CO2-scrubbing system. The project encompasses the use of algae for energy production along with other eco-friendly technologies, such as solar and wind energy harvesting. This holistic system effectively purifies the atmosphere of CO2 while concurrently generating energy, cultivating food, treating wastewater, and extracting biodiesel from algae. Positioned at the top of the two towers, the system’s two carbon-scrubbing plants consist of CO2-scrubbing modules and PBRs. This innovative carbon-scrubbing technology facilitates the provision of CO2 to the algae bioreactor, overcoming the challenges related to CO2 transportation and storage. Complementing the energy generation of the system, photovoltaic and solar thermal panels are deployed on semicircular balconies exposed to sunlight, augmenting electricity production and enhancing system autonomy. Additionally, a phytoremediation garden has been seamlessly integrated into the parking structure of the west tower. The resulting purified water can be recycled for various purposes, such as restroom usage in the Marina or irrigation for vertical farming, thereby further enhancing the sustainability of the system [1].

Figure 4. Elucidative demonstration for the application of algae technology [21].

Figure 4. Elucidative demonstration for the application of algae technology [21].

Many other prize-winning projects have significant potential for the same end as all aforementioned projects, a carbon-neutral environment. The use of urban-integrated algae is also being explored to promote cleaner air and improve aesthetics. Over 4 days from 21st November to 24th November 2022, The Emirates Environmental Group conducted the 22nd cycle of the annual Inter-College Environmental Public Speaking Competition, which provides a special platform for youth of the Arab region to voice their concerns on current sustainability issues and suggest some sustainable solutions [22].

The topic of this research paper was submitted in relation to these challenges, where it was subsequently named the first runner-up by the author and her students in the 22nd Cycle of Inter College Environmental Public Speaking Competition, Dubai, under the title, ‘’The next generation of cities’’; it presented a new proposal for the use of algae-powered building in new cities.

6. Algae Building Technology in Egypt

6.2. Application in Egypt

Using algae in Buildings to supply their energy (heat and electricity) can aid as a substitute building system. Microalgae enclosures buildings not only generate clean energy but also play a role in GHG mitigation and can be considered as a carbon-neutral power source of energy. In addition to the positive environmental effects, they moreover have financial effectiveness due to the lessening of energy and operational costs that produce lower life cycle costs.

Adopting algae façades by building sector, environmental, technical, political, economic, and the social performance of practically implemented algae-integrated buildings should be evaluated in decision-making process. Sustainable design considerations should be conducted in early stages to make the process time- and cost-efficient.

This part presents the final stage outlined in methodology and suggests integrating algae building façades as a solution on the architectural and the urban level in Egypt to guide more environmentally friendly design decisions to reduce our dependence on fossil fuels, minimize the building sector’s carbon footprint, and convert buildings from energy consumers to energy producers.

The study focused on applying these systems to the area of Prince Muhammad Ali Palace in Manial, Located in Cairo, Egypt.

Reasons for choosing the location case study:

It is a dense area with a distinguished historical location

- The Muhammad Ali Palace area is a strategic location on the urban scale where different important buildings are located in a central place (educational, medical, residential, and commercial)

Historical Background:

The palace is located in the north of Rawda Island, on the small branch of the Nile River in front of Kasr Al-Aini. The total area of the palace is approximately 61,711 square meters.

About the palace

The Prince Muhammad Ali Palace Museum in Manial is one of the most beautiful and important cultural museums in Egypt. The palace contributes to the preservation of an important period of time in the history of modern Egypt, with its creative architectural character. It is considered a universal school for various elements of Islamic arts [39].

It was established by Prince Muhammad Ali Tawfiq in the period between 1319 and 1348 AH/1900-1939. The palace consists of an external wall surrounding the entrance to the palace and includes within its walls the reception palace, the clock tower, the avenue, the mosque, the hunting museum, the residence palace, the throne palace, the private museum, the Golden Hall, and unique garden surrounding the palace.

Figure 5. Maps of Muhammad Ali Palace and surrounded areas, Egypt (Google Maps).

Figure 5. Maps of Muhammad Ali Palace and surrounded areas, Egypt (Google Maps).

The palace has been renovated and opened its doors to the public as a very important destination. Activities of Prince Muhammad Ali Palace in Manial as a tourist destination

Currently, the best activities for visitors to Prince Muhammad Ali Palace include the following:

- Visitors can walk around the place and enjoy seeing the architectural elements used when constructing this palace.

-It includes many rooms that serve specific functions. These rooms can be explored, and their design can be noted, as well as the furniture and interior architecture that adorns these rooms, and the purpose for which these rooms were created.

-Some halls display historical collectibles that mark important periods of time, including old maps, old weapons, historical documents, jewelry, and antiquities.

- Inscriptions and ornaments that decorate the walls in the reception hall can be seen.

-Art galleries featuring works of art, statues, sculptures, and paintings that the most famous artists excelled at, as well as valuable mosaic pieces, can also be seen.

-The landscaping elements of the sit include benches, water ponds, and fountains in the garden.

-The Tense Salon in the Saray Residence and the Blue Salon can be visited.

6.3. Aims of the Proposed Solutions Are as Follows

On the urban level: the aim is to provide shading and raise public awareness of alternative fuels.

-Aesthetic aspects of the biological envelope can be a potential driver of public acceptance.

-Touristic attraction and the relationship between new and old characteristics and innovative architectural features can be encouraged.

-Environmental applications that can mitigate carbon footprints, treat wastewater or other contaminants, and improve air quality can be presented.

-Green features lead to improved quality of life, better physical and psychological wellbeing, and performance for users. They can also be used to create play areas for children.

-Economic aspects can be demonstrated: minimizing the cost and consumption of energy.

- Application on the city scale can prompt a superior comprehension of this innovation and stick to normal examples.

Table 3. Suggestions and evaluation of the proposals and their relation to the Sustainable Development Goals (developed by Authors).

Table 3. Suggestions and evaluation of the proposals and their relation to the Sustainable Development Goals (developed by Authors).

6.3.1. Analysis of Proposed Ideas

The ideas presented at the architectural and urban levels: The facades can be covered with panels of algae, as algae multiplies as a result of photosynthesis, and with a heat recovery system and solar panels, the building becomes autonomous in terms of its need for energy.

Algae is grown in order to generate energy, monitor the flow of light and shade the building, as the facades become in a constant state of movement and change their colour. The production of renewable energy will not take place inside a hidden energy center, but rather will be part of the idea of forming the space.

Egypt is adopting many projects and initiatives to achieve Egypt’s Vision 2030 to achieve the goals of UN Sustainable Development Goals.

This development represents a sustainable solution for urban energy production, so the idea of implementing algae in architecture in the dense spaces in Egypt showcasing this work will be tested in a real-life scenario.

Interviews have been conducted in Muhamed Ali Palace Area in Cairo, Egypt area in order to measure satisfaction by users, residents, and professionals where questions include their vision towards the social, the technical, economic, regulatory, and environmental aspects of implementing algae facades.

Finally, key opportunities and barriers that may impact the successful adoption of this technology can be taken in consideration.

Figure 11 depicts sample of interview answers of the sample that is used in this survey. The number of the sample was 350, 305 responded. The answers choices between: agree, maybe, disagree. In order to gather relevant information specific to the local context and potential challenges.

According to the interview and answers from respondents, the main positive feedback about implementing Algae has been deducted as shown in Figure 12.

6.4. Implementation of the Technology in Egypt

The following points discuss the proper steps required to implement such technology in Egypt.

- Conduct a feasibility study to evaluate the suitability and potential of using an algae facade in a specific location in Egypt, considering factors such as climate, sunlight availability, water quality, and the energy requirements of algae cultivation.

- During design and construction, collaborate with architects, engineers, and algae experts to design a facade system that integrates algae cultivation into the building’s exterior, considering aspects such as cultivation modules, flow systems, lighting conditions, and structural requirements.

- For algae selection, identify suitable algae species that can thrive in the climate and water conditions of Egypt. Consider algae species that are fast-growing, have high biomass productivity, and can withstand the local environmental conditions.

- During cultivation setup, set up the necessary infrastructure for algae cultivation, including tanks or photobioreactors, water supply systems, lighting systems, and monitoring equipment. Install the cultivation modules on the building’s facade according to the design.

- Concerning maintenance and monitoring, implement a maintenance plan to ensure proper algal growth and health. This would include regular monitoring of water quality, nutrient levels, and temperature, as well as periodic cleaning and the removal of excessive algae biomass.

- For integration with the building, connect the algae facade system to the building’s energy and water systems to optimize energy and resource use. Consider coordinating the system with the building’s HVAC (heating, ventilation, and air conditioning) and water treatment frameworks to use the algae biomass for energy creation and wastewater treatment.

- In terms of education and awareness, foster instructive projects and mindfulness missions to illuminate general society about the advantages and capability of green growth veneers. This may involve collaborating with universities, hosting public events, and providing training sessions to professionals and residents, and the challenges should be met in order to take the actions required to achieve sustainable development [46,47]

- Concerning evaluation and optimization, continuously monitor and evaluate the performance of the algae facade system, making necessary adjustments and optimizations based on the collected data. This may involve improving cultivation techniques, adjusting nutrient levels, or upgrading the infrastructure if needed.

Moreover, implementing an algae facade in Egypt would require collaboration between various stakeholders, including government bodies, research institutions, architectural firms, and construction companies. Adequate funding, regulatory support, and public acceptance would be essential for the successful implementation of such a project. In the context of Egypt, this concept can have several benefits and contribution to the sustainable development of the country.

Figure 13. Steps of implementation (developed by the authors).

Figure 13. Steps of implementation (developed by the authors).

Table 2. Elucidation of substantial aspects to consider and how to approach it.

Table 2. Elucidation of substantial aspects to consider and how to approach it.

Aspects	Sustainable approach
Energy production	Algae can be used to produce biofuels, which can reduce Egypt’s dependence on fossil fuels. The country has ample sunlight and warm temperatures, which are favorable for algal growth. By utilizing algae for energy production, Egypt can reduce carbon emissions and promote a cleaner and more sustainable energy system.
Carbon capture	Algae have the ability to absorb carbon dioxide from the atmosphere through photosynthesis. By incorporating algae facades on buildings in Egypt, the country can potentially offset some of its carbon emissions and combat climate change.
Water treatment	Egypt faces water scarcity issues due to limited freshwater resources. Algae can be used for wastewater treatment and purification, helping to conserve and reuse water resources. By implementing algae facade systems, buildings can potentially contribute to water conservation efforts and reduce the strain on freshwater supplies.
Improved air quality	Algae can help develop air quality by retaining pollutants such as nitrogen dioxide and particulate matter. Egypt, particularly its urban areas, faces significant air pollution challenges, which can have detrimental effects on public health. Incorporating algae facade systems in buildings can help mitigate air pollution and create healthier environments.
Aesthetically pleasing design	Algae facades can also enhance the aesthetic appeal of buildings. Algae can be grown in various colors and patterns, allowing for creative and visually appealing facades. By integrating algae into architectural designs, Egypt can promote sustainable development while also creating visually striking landmarks.
Environmental sustainability	Algae are highly efficient at absorbing carbon dioxide and releasing oxygen through photosynthesis. Integrating algae systems in buildings can help reduce carbon emissions and improve indoor air quality.
Energy efficiency	Algae can be used to produce biofuels, such as biodiesel or biogas, through the conversion of their biomass. Implementing algae-based energy systems can help reduce the dependence on fossil fuels and promote renewable energy sources.

Adopting algae facades in Egypt can offer multiple benefits, including renewable energy production, carbon capture, water purification, improved air quality, and aesthetically pleasing designs. While this technology is still in its early stages of development, its implementation can contribute to Egypt achieving its sustainable development goals and help address environmental challenges in the country.

7. Conclusions

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