Sustainable Green Data Farming
What do we mean by sustainable green data farm?
A sustainable green data farm is an integrated vertical farm with a data centre where the energy is derived from solar panels and wind turbines plus water for cooling that is derived from the evaporation of sea water (or from a stream). For a modern day data centre that takes a lot of energy and water to run it efficiently, there is a need to provide it with plenty of green energy and water for cooling - the energy part is provided by solar panels and wind turbines and the water is derived from the evaporation and condensation of stream water. If however there is no stream water nearby then we will have to use recycled water from the sewage system with additional water from the condensation of evaporated cooling water. Additionably we can also use condensed water from an atmosphere water generator that is powered by either solar or wind. That is what we called a totally green data centre - also bear in mind that we can also run a vertical farm to produce vegetables and acquatic produce which will make it food, energy and water secured!
Let us look at how we can generate water.
Vapor Concentration
In the vapour concentration approach, water vapour from the atmosphere is selectively captured in a hygroscopic material and then regenerated either by using an external condenser or thermal energy to condense the water vapour captured under ambient conditions. The heart of this type of AWG approach is the sorbent material, which captures the water vapour through physisorption or chemisorption. The advantage of this approach lies in its ability to operate under low RH conditions (< 20%), which extends the application of AWG in arid climates. If the thermal energy or heat required for regeneration of the sorbent is provided by concentrating the solar radiation and condensation at ambient temperature, then this approach can offer a sustainable, passive AWG solution. Although many conventional hygroscopic materials exist, such as silica gel, zeolite, etc., the water uptake under low RH conditions, high regeneration temperature, sorbent stability, sorption kinetics, and cyclic operation are the major challenges to its potential use in AWG. Sorption-based AWG systems can work in continuous mode with multiple sorption beds or sorption bed rotation and batch mode with multiple sorption cycles in a day or in discontinuous mode with night-time adsorption and daytime desorption (Poredoš et al., 2022)
Yet another promising method is that of solar-driven interfacial evaporation is a promising technology for freshwater production from seawater, but salt accumulation on the evaporator surface hinders its performance and sustainability. A simple and green strategy to fabricate a three-dimensional porous grapheme spiral roll (3GSR) that enables highly efficient solar evaporation, salt collection, and water production from near-saturated brine with zero liquid discharge (ZLD). The 3GSR design facilitates energy recovery, radial brine transport, and directional salt crystallization, thereby resulting in an ultrahigh evaporation rate of 9.05 kgm−2h−1 in 25wt % brine under 1-sun illumination for 48h continuously. Remarkably, the directional salt crystallization on its outer surface not only enlarges the evaporation area but also achieves an ultrahigh salt collection rate of 2.92kgm−2h−1, thus enabling ZLD desalination. Additionally, 3GSR exhibits a record-high water production rate of 3.14 kgm−2h−1 in an outdoor test. This innovative solution offers a highly efficient and continuous solar desalination method for water production and ZLD brine treatment, which has great implications for addressing global water scarcity and environmental issues arising from brine disposal.
Tank like devices called solar stills use the sun to evaporate dirty or salty water and condense the vapour into safe drinking water. Now, researchers have developed a new material that speeds the process of evaporation, enabling a small solar still to provide all the drinking water one family needs. Recently, researchers have been working to upgrade solar stills as a cheap, low-tech alternative. The traditional still is little more than a black-bottomed vessel filled with water and topped with clear glass or plastic. The black bottom absorbs sunlight, heating water so that it evaporates and leaves the contaminants behind. The water vapour then condenses on the clear covering and trickles into a collector. However, providing enough drinking water for a small family requires a still around 5 square meters in size. Operating at their theoretical best, such devices can only produce 1.6 L/h/m2.
Scientist at the University of Texas in Austin, recently reported a way around this limit. It involves hydrogels, polymer mixtures that form a 3D porous, water—absorbent network. The scientists fashioned a gel like sponge of two polymers—one a water-binding polymer called polyvinyl alcohol (PVA), the other a light absorber called polypyrrole (PPy)—which they then placed atop the water's surface in Inside the gel, a layer of water molecules bonded tightly to the PVA, each forming multiple chemical links known as hydrogen bonds. But with so much of their bonding ability tied up with the PVA, the bound water molecules bind only loosely to other nearby water molecules, creating what the scientist calls "intermediate water”. Because intermediate water molecules share fewer bonds with their neighbours, they evaporate more readily than regular water. And when they do, they're immediately replaced by other water molecules in the still. Using this technology, the scientist solar still produced 3.2 L/h/m2 of water, double the theoretical limit, as reported last year in Nature Nanotechnology.
Tank like devices called solar stills use the sun to evaporate dirty or salty water and condense the vapour into safe drinking water. Now, researchers have developed a new material that speeds the process of evaporation, enabling a small solar still to provide all the drinking water one family needs. Recently, researchers have been working to upgrade solar stills as a cheap, low-tech alternative. The traditional still is little more than a black-bottomed vessel filled with water and topped with clear glass or plastic. The black bottom absorbs sunlight, heating water so that it evaporates and leaves the contaminants behind. The water vapour then condenses on the clear covering and trickles into a collector. However, providing enough drinking water for a small family requires a still around 5 square meters in size. Operating at their theoretical best, such devices can only produce 1.6 L/h/m2. Scientist at the University of Texas in Austin, recently reported a way around this limit. It involves hydrogels, polymer mixtures that form a 3D porous, water—absorbent network. The scientists fashioned a gel like sponge of two polymers—one a water-binding polymer called polyvinyl alcohol (PVA), the other a light absorber called polypyrrole (PPy)—which they then placed atop the water's surface in Inside the gel, a layer of water molecules bonded tightly to the PVA, each forming multiple chemical links known as hydrogen bonds. But with so much of their bonding ability tied up with the PVA, the bound water molecules bind only loosely to other nearby water molecules, creating what the scientist calls "intermediate water”. Because intermediate water molecules share fewer bonds with their neighbours, they evaporate more readily than regular water. And when they do, they're immediately replaced by other water molecules in the still. Using this technology, the scientist solar still produced 3.2 L/h/m2 of water, double the theoretical limit, as reported last year in Nature Nanotechnology.
Yet another promising method is that of solar-driven interfacial evaporation is a promising technology for freshwater production from seawater, but salt accumulation on the evaporator surface hinders its performance and sustainability. A simple and green strategy to fabricate a three-dimensional porous grapheme spiral roll (3GSR) that enables highly efficient solar evaporation, salt collection, and water production from near-saturated brine with zero liquid discharge (ZLD). The 3GSR design facilitates energy recovery, radial brine transport, and directional salt crystallization, thereby resulting in an ultrahigh evaporation rate of 9.05kgm−2h−1 in 25wt % brine under 1-sun illumination for 48h continuously. Remarkably, the directional salt crystallization on its outer surface not only enlarges the evaporation area but also achieves an ultrahigh salt collection rate of 2.92 kg m−2 h−1, thus enabling ZLD desalination. Additionally, 3GSR exhibits a record-high water production rate of 3.14 kg m−2 h−1 in an outdoor test. This innovative solution offers a highly efficient and continuous solar desalination method for water production and ZLD brine treatment, which has great implications for addressing global water scarcity and environmental issues arising from brine disposal.
New Material
The development of advanced materials with new properties contributes to enhancing the photo-thermal conversion efficiency. Hydrogels have emerged as encouraging material platforms for solar-driven water purification because of good water absorption, water retention and water transport. The rational design of hydrogel structures can lower the heat loss during heat transfer process to improve the photo-thermal conversion efficiency. Hydrogels are combined with photo-thermal materials (including carbon-based materials, polymer materials, semiconductor materials, plasmonic materials and hybrid materials) to prepare hydrogel-based solar evaporators.
Solar evaporators inspired by nature. Evaporation systems with bionic structures such as roots, stems, leaves, and even animal tissues can not only promote water transport inside the absorbers but also accelerate the solar water evaporation process, leading to a high evaporation rate and energy conversion efficiency. Most significantly, the promising applications of solar vapour generation for seawater desalination, water purification, electricity generation, evaporative cooling and photo catalytic degradation is highly recommended for further research and development. Here, we propose a nano confinement strategy altering inherent properties of water for solar-driven water evaporation using a highly uniform composite of vertically aligned Janus carbon nanotubes (CNTs). The water evaporation from the CNT shows the unexpected diameter-dependent evaporation rate, increasing abnormally with decreasing nano channel diameter. The evaporation rate of CNT10@AAO evaporator thermodynamically exceeds the theoretical limit (1.47 kg m−2 hour−1 under one sun). A hybrid experimental, theoretical and molecular simulation approach provided fundamental evidence of different nano-confined water properties. The decreased number of H-bonds and lower interaction energy barrier of water molecules within CNT and formed water clusters may be one of the reasons for the less evaporative energy activating rapid nano-confined water vaporization.
Perhaps a simpler system is more viable. A completely passive solar-powered desalination system developed by researchers at MIT and in China could provide more than 1.5 gallons of fresh drinking water per hour for every square meter of solar collecting area. Such systems could potentially serve off-grid arid coastal areas to provide an efficient, low-cost water source. The system uses multiple layers of flat solar evaporators and condensers, lined up in a vertical array and topped with transparent aerogel insulation. It is described in a paper appearing today in the journal Energy and Environmental Science, authored by MIT doctoral students Lenan Zhang and Lin Zhao, postdoc Zhenyuan Xu, professor of mechanical engineering and department head Evelyn Wang, and eight others at MIT and at Shanghai Jiao Tong University in China.
The key to the system's efficiency lies in the way it uses each of the multiple stages to desalinate the water. At each stage, heat released by the previous stage is harnessed instead of wasted. In this way, the team’s demonstration device can achieve an overall efficiency of 385 per cent in converting the energy of sunlight into the energy of water evaporation.
The device is essentially a multilayer solar still, with a set of evaporating and condensing components like those used to distil liquor. It uses flat panels to absorb heat and then transfer that heat to a layer of water so that it begins to evaporate. The vapour then condenses on the next panel. That water gets collected, while the heat from the vapour condensation gets passed to the next layer. Whenever vapour condenses on a surface, it releases heat; in typical condenser systems, that heat is simply lost to the environment. But in this multilayer evaporator the released heat flows to the next evaporating layer, recycling the solar heat and boosting the overall efficiency.
“When you condense water, you release energy as heat,” Wang says. “If you have more than one stage, you can take advantage of that heat.” Adding more layers increases the conversion efficiency for producing potable water, but each layer also adds cost and bulk to the system. The team settled on a 10-stage system for their proof-of-concept device, which was tested on an MIT building rooftop. The system delivered pure water that exceeded city drinking water standards, at a rate of 5.78 litres per square meter (about 1.52 gallons per 11 square feet) of solar collecting area. This is more than two times as much as the record amount previously produced by any such passive solar-powered desalination system, Wang says.
Theoretically, with more desalination stages and further optimization, such systems could reach overall efficiency levels as high as 700 or 800 per cent, Zhang says.
Unlike some desalination systems, there is no accumulation of salt or concentrated brines to be disposed of. In a free-floating configuration, any salt that accumulates during the day would simply be carried back out at night through the wicking material and back into the seawater, according to the researchers.
Their demonstration unit was built mostly from inexpensive, readily available materials such as a commercial black solar absorber and paper towels for a capillary wick to carry the water into contact with the solar absorber. In most other attempts to make passive solar desalination systems, the solar absorber material and the wicking material have been a single component, which requires specialized and expensive materials, Wang says. “We’ve been able to decouple these two.” The most expensive component of the prototype is a layer of transparent aerogel used as an insulator at the top of the stack, but the team suggests other less expensive insulators could be used as an alternative. (The aerogel itself is made from dirt-cheap silica but requires specialized drying equipment for its manufacture.)
Wang emphasizes that the team’s key contribution is a framework for understanding how to optimize such multistage passive systems, which they call thermally localized multistage desalination. The formulas they developed could likely be applied to a variety of materials and device architectures, allowing for further optimization of systems based on different scales of operation or local conditions and materials.
One possible configuration would be floating panels on a body of saltwater such as an impoundment pond. These could constantly and passively deliver fresh water through pipes to the shore, as long as the sun shines each day. Other systems could be designed to serve a single household, perhaps using a flat panel on a large shallow tank of seawater that is pumped or carried in. The team estimates that a system with a roughly 1-square-meter solar collecting area could meet the daily drinking water needs of one person. In production, they think a system built to serve the needs of a family might be built for around $100.
The researchers plan further experiments to continue to optimize the choice of materials and configurations, and to test the durability of the system under realistic conditions. They also will work on translating the design of their lab-scale device into a something that would be suitable for use by consumers. The hope is that it could ultimately play a role in alleviating water scarcity in parts of the developing world where reliable electricity is scarce but seawater and sunlight are abundant.
“This new approach is very significant,” says Ravi Prasher, an associate lab director at Lawrence Berkeley National Laboratory and adjunct professor of mechanical engineering at the University of California at Berkeley, who was not involved in this work. “One of the challenges in solar still-based desalination has been low efficiency due to the loss of significant energy in condensation. By efficiently harvesting the condensation energy, the overall solar to vapour efficiency is dramatically improved. … This increased efficiency will have an overall impact on reducing the cost of produced water.”
The research team included Bangjun Li, Chenxi Wang and Ruzhu Wang at the Shanghai Jiao Tong University, and Bikram Bhatia, Kyle Wilke, Youngsup Song, Omar Labban, and John Lienhard, who is the Abdul Latif Jameel Professor of Water at MIT. The research was supported by the National Natural Science Foundation of China, the Singapore-MIT Alliance for Research and Technology, and the MIT Tata Center for Technology and Design.
Water scarcity represents an emerging, severe global concern. According to research conducted by the World Health Organization, one-third of the world's population lacks access to clean water and the situation is expected to be exacerbated due to climate change by the year 2050 (Boretti and Rosa, 2019). New technological interventions are urgently required to minimize groundwater stress and complement the suite of existing water generation technologies. In this context, atmospheric water generation (AWG), which extracts water from the humidity present in the atmosphere, could be viewed as a futuristic approach to address the issue of water scarcity. The water present in the atmosphere can be considered as a nearly inexhaustible resource for fresh water because at any given time approximately 13,000 km3 of fresh water is in the atmosphere (Gleick, 1993; Graham et al., 2010), which is naturally replenished through the hydrological cycle.
AWG(atmospheric water generation) offers several advantages over conventional, centralized technologies, such as minimal infrastructure, ease of installation, low space requirements, and rapid emergency response capability. In addition, AWG processes will not negatively impact the environment since the daily hydrological cycle will replenish any water extracted from the atmosphere. Potentially extractable water is present in our atmosphere in the form of fog and water vapour. The approaches to extract atmospheric water can be broadly classified as follows: active refrigeration, passive cooling and collection, vapour concentration, and hybrid approaches
Under hot and humid conditions, the water content in the air will be high, and the dew point temperature will be close to the air temperature. Thus, the energy input required is less when the air has a high dew point, such that most of the energy supplied will be utilized in the condensation of moist air.
Passive Collection
In the passive collection approach, water generation is achieved through passive means with net-zero energy investment. Fog and dew harvesting methods are the two main techniques that have been proposed under this approach (Fessehaye et al., 2014; Korkmaz and Kariper, 2020; Sharan et al., 2017; Tomaszkiewicz et al., 2015). In fog harvesting, water in the form of fog or aerosol droplets is trapped in specially designed structures called fog nets (see Fig. 5). Fog nets, which are usually vertical mesh-like structures, allow fog droplet growth by coalescence and the removal of large drops is driven by gravity to catchments that collect them for further use.
Hybrid Approaches
A universal AWG approach is to use multiple technologies in a single device such that it can work effectively under a wide operational band and ensure scalable water generation with minimal energy consumption (Raveesh et al., 2021). Hybrid AWG approaches pull together multiple AWG techniques to obtain a synergistic effect and improve overall efficiency (Shafeian et al., 2022). Desiccant wheels, solar inputs, and brine evaporation can be used to pre-treat the air to create hot and humid conditions before the air enters the cooling and condensation components, resulting in greater water production. Thus, active refrigeration systems can be operated under their best operating conditions with mixed pre-treatment systems to enable good performance regardless of weather conditions. Tu and Hwang (2019) showcased a configuration that had multiple desiccant wheels before a VCR-AWG system to increase the humidity ratio of the incoming air. Bahrami and Bagheri (2018) used a sorption column and a specially designed operational strategy with a VCR-AWG system. Kwan et al. (2020) fed exhaust flue gas from a fuel cell to an AWG system. In another study, Ghosh et al. (2015) demonstrated harvesting of water from cooling tower plumes using a fog net. Although the possibilities for such hybrid approaches have not been exhausted, they offer an excellent chance to make a breakthrough in the currently available AWG technologies.
The Simplest Method of collecting water
Energy
Solar
The option to generate renewable energy on-site is not available to all data centers. Moreover, where it is available, it can be complex and involve high upfront costs. However, if there is a large stretch of land available, then solar should be the better choice.
This option does, however, offer the prospect of a significant return on investment. By making data centers less reliant on purchased electricity, it increases their resilience and lowers their running costs.
Recent trends in solar power adoption for data centers and IT infrastructure are focused on increasing efficiency and reducing costs. Advancements in photovoltaic technology, such as the use of bifacial solar panels and solar tracking systems, enhance energy capture. Additionally, research is being conducted on innovative approaches such as solar-powered cooling systems and direct current (DC) power distribution within data centers to further optimize solar power utilization.
Big Tech firms such as Amazon and Microsoft seek clean energy to power data centers that are the backbone of the Internet and artificial intelligence applications. The economic argument for renewables has also strengthened, they say, as the price of solar modules and batteries has fallen.
As solar is only available during the sun shining, there should be another form of energy to tap and that should be wind. Wind does blow twenty four hours especially in areas that is near the sea –which will give a steady supply of electricity. It would be better to have a battery system to back up the supply of electricity. Other forms of energy includes hydro, geothermal and biomass.
Home grown vegetables and fish
Vertical farming is a modern agricultural strategy that uses vertically stacked layers to grow crops indoors, often employing soil-less farming methods like hydroponics, aquaponics, and aeroponics.
Since there is the availability of energy, it would be the good choice of having a facility to grow vegetables and rearing of fish. Modern vertical farms will normally include an aquaponics center – the idea is to secure food supply.
Green Building Materials
For those who are concerned with the deteriorating environment, there is always the need to use green building materials to erect their buildings, this will include the construction of data centers. Hempcrete comes to mind as it will enable the use of less steel and concrete, thus making the building more green.