Patent Application
20230373877
The use of fertilizer in agriculture has become an essential component of ensuring adequate food supply to support a growing population, especially in developing countries such as sub-Saharan Africa, where inadequate access to affordable fertilizer results in adverse hunger and famine in the region. To meet the increasing demand, synthetic fertilizers, including nitrogen (N), phosphorous (P), and potassium (K), are prevalent in the commercial farming industry. Nitrogen fertilizer is the main nutrient for plant growth which accounts for over 50% of global synthetic fertilizers globally. However, when nitrogen fertilizer is applied to plants, only 30-40% of nitrogen is absorbed by the plants, and the rest is wasted or drained into the water, causing water pollution, or “nitrogen runoff.”
In the United States and worldwide, most nitrogen fertilizer is based on ammonia produced using the Haber-Bosch process, an almost century-old process that has been extensively developed, with current implementations depicting efficiencies close to the theoretical maximum. Nevertheless, the Haber-Bosch process presents important limitations. Specifically, the Haber-Bosch process requires high temperatures (300° to 500° C.) and high-pressures (60 to 180 atm), resulting in complex large-scale installations with significant energy consumption, which generally contribute to high amounts of environmental emission byproducts (such as CO2). There are also high transportation costs associated with fertilizer that vary based on fuel prices. By some estimates, fertilizer production releases approximately 1.4% of global carbon dioxide CO2 emissions and consumes almost 2.0% of global energy production needs.
Thus, decarbonizing fertilizer manufacturing would improve sustainability and reduce energy use. An environmentally beneficial system would allow for a decentralized and decarbonized approach to fertilizer production.
In a first aspect, an apparatus for generating low-temperature plasma to synthesize fertilizer using ambient air, plasma, and water to create NO3− (nitrates) as a fertilizer solution (Plasma-Activated Water, or PAW) is disclosed. The system may be used for on-site and on-demand delivery by integrating it into an existing drip irrigation system or other irrigation approaches.
In a second aspect, a method of synthesizing nitrogen-based fertilizer from air and water on-site uses low-temperature atmospheric air plasma powered by electricity mainly from renewable energy sources such as solar and wind.
Exemplary embodiments will be described in detail herein, with examples thereof represented in the drawings. When the following descriptions involve the drawings, like numerals in different drawings represent like or similar elements unless otherwise indicated. Implementations described in the following exemplary embodiments do not represent all implementations consistent with the present disclosure. Instead, they are merely examples of apparatuses and methods consistent with some aspects of the present disclosure as detailed in the appended claims.
Plasma is an ionized gas consisting of electrons, ions, neutrals, and molecules. Generally, plasma in technological applications are characterized as being of two types: thermal and nonthermal plasma. In thermal plasma, both electrons and so-called heavy species in the plasma (atoms, ions, molecules) have approximately the same high temperature, usually between 8,000 to 20,000 K. However, nonthermal plasma exhibits higher electron temperature (typically higher than ˜11,000) compared to the background gases and heavy species. Further, non-thermal plasma applications generally have higher energy efficiency and selectivity. As disclosed herein, the use of solar as an energy source to generate the transferred-discharge plasma mode as well as the in-situ production of fertilizer in a distributed manner is a novel approach that may help smaller farms, communities, and countries that do not have access to large fertilizer manufacturing plants utilizing the Haber-Bosch process.
The system and method disclosed herein provides nitrogen fertilizer in a low-cost, decentralized manner while mitigating nitrogen pollution and carbon dioxide (CO2) emissions commonly associated with fertilizer production. Farmers may adapt their existing drip irrigation systems to use fertilizer from a modular system. The technology tackles three main issues: first, this technology utilizes electricity mainly from renewable energy sources such as solar and wind help mitigate climate change and pollution from the Haber-Bosch fertilizer production process. Second, it minimizes nitrogen runoff where chemical fertilizer is over-utilized, causing water pollution and is harmful to the ecological system. Finally, it is economically viable in a way that lowers expenses and increases food production, contributing significantly to global food security and sustainable development. This system produces fertilizer on-site, eliminating transportation costs. The systems and methods disclosed herein may be utilized in remote off-grid areas, benefiting disadvantaged communities. The system is compact and modular, making it linearly-scalable to meet the growing demand for sustainable carbon-neutral fertilizer.
Controller 104 includes several components. In the representative embodiment shown in
Plasma reactor 110 receives water from water supply tank 136, which is treated with plasma generated by powered electrode 106 and ground electrode 108. After treatment, plasma-activated water (PAW) may be stored in storage tank 138 for a period of time until used or sent directly to drip irrigation line 120. In embodiments, the period of time may be 30 min up to one day or more, depending on irrigation needs. The reactivity produced by the plasma leads to nitrates being formed continuously after plasma treatment up to approximately one day after plasma treatment.
Drip irrigation line 120 is a water distribution system that will supply water and fertilizer to plants. A pump (not shown) may be used to move PAW from plasma reactor 110 or storage tank 138 into drip irrigation line 120, or components of system 100 may be positioned so that drip irrigation lines 120 are gravity fed. Valves (not shown) may be installed between at various locations to manage the flow of water in system 100. They may be manually opened and closed, or they may be controlled by controller 104. Water pumps may be used to maintain a certain pressure level suitable for the water delivery lines in drip irrigation systems. Further, sensors may be installed at various locations to collect data about the operation of system 100 including water levels and flow, nitrate concentration of PAW, or soil moisture, for example, which may be used by controller 104 to manage the operation of system 100.
Lid 112 is provided with holes to allow ambient air to enter plasma reactor 110, as will be discussed in more detail below. As shown, powered electrode 106 is secured in lid 112 while ground electrode 108 enters plasma reactor 110 at the bottom. Other arrangements of ground electrode 108 are possible as long as the tip of ground electrode 108 is submerged below surface 114 of the water inside plasma reactor 110. powered electrode 106 is secured in lid 112 so that a tip of powered electrode 106 is maintained at a distance of approximately 10 mm above surface 114 of the water. In embodiments, the distance between the tip of powered electrode 106 and surface 114 may be from approximately 5 to 15 mm.
Water is provided to plasma reactor 110 from a water supply tank (not shown) through inlet 116. A valve may be provided to control how much water is allowed to enter plasma reactor 110 so as to maintain the correct distance between powered electrode 106 and surface 114. The valve (not shown) may be manually controlled or automated. Outlet 118 from plasma reactor 110 may be connected to a storage tank (not shown) for storing plasma-activated water (PAW). The storage tank may be connected to drip irrigation lines 120 for providing plasma-activated water to plants. In embodiments, outlet 118 may be connected directly to drip irrigation lines 120. In further embodiments, manual or programmatically controlled valves may be used between any of outlet 118, drip irrigation lines 120, and a storage tank. The system of
In embodiments, all or some of the components of system 100 except drip irrigation lines 120 may be located in a compact enclosure that is portable and easily moved. Specifically, charge controller 124 and power supply 130 may be integrated in a single integrated circuit of a few square centimeters in size. In embodiments, an electric battery may not be needed if the system is designed to operate only when the sun is shining, hence producing fertilizer only when plants need it. In embodiments, selected components of system 100 may be positioned either indoor or outdoor as needed for a particular application.
In embodiments, plasma reactor 110 may include two or more powered electrodes 106. When using a plurality of powered electrodes, they are positioned at a minimum distance from each other to prevent interaction between powered electrodes instead of between each powered electrode and surface 114 of the water inside plasma reactor 110.
In step 502, water is added to plasma reactor 110. In an example of step 502, water may be pumped from a storage tank or other water source. A submersible pump may be used. Other methods of adding water to plasma reactor 110 may also be used.
In step 504, ground electrode 108 positioned in plasma reactor 110. In an example of step 504, ground electrode 108 is inserted through lid 112 of plasma reactor 110 and positioned so that the tip of ground electrode 108 is positioned below a surface 114 of the water in the plasma reactor.
In step 506, powered electrode 106 is positioned in plasma reactor 110. In an example of step 504, powered electrode 108 is inserted through a stainless steel or similar fitting in lid 112 of plasma reactor 110 and positioned so that the tip of powered electrode 106 is located approximately 10 mm above surface 114 of the water. In embodiments, the tip of powered electrode 106 may be positioned between approximately 5 and 15 mm. In further embodiments, step 506 may be performed before or after step 504.
In step 508, power supply 130 is connected to a renewable energy source. In an example of step 508, controller 104 is connected to PV panel 102 or another renewable energy source and stores electrical charge in battery 126 for use by power supply 130.
In step 510, power supply 130 is turned on at an appropriate voltage level setting for a first period of time to generate PAW. In an example of step 510, power supply 130 may provide voltage that varies from 0 to 40 kV for a first period of time. In an embodiment, the voltage may be between 1 and 5 kV. In embodiments, the first period of time may be approximately six to eight hours, depending on the season. Power supply 130 may be turned off after the first period of time. In embodiments, power supply 130 may operate continuously when the sun is shining, thus producing fertilizer when plants need it. When connected to electrodes 106 and 108, an electric discharge is generated from the tip of powered electrode 106 impinging on the water. This electric discharge consists of partially ionized air (mainly nitrogen and oxygen) when it reacts with water to produce nitrates (NO3−) and some auxiliary ions such as nitrites and ammonium. In this configuration, the water is electrically coupled, and the electrical design of the system can provide direct control over the amount of electric current and power delivered to the water. In embodiments, the first period of time may be selected to produce approximately 100-200 milligrams of nitrates per liter of water in plasma reactor 110 when power supply 130 is providing 20 kV of voltage between powered electrode 106 and ground electrode 108.
In step 512, PAW is stored for a second period of time before being distributed to drip irrigation lines. In an example of step 512, PAW may be stored in plasma reactor 110 or a separate storage tank 138 for a second period of time between approximately 30 minutes and 48 hours. PAW may be moved using a pump or through gravity. The flow rate of PAW into drip irrigation lines 120 may be adjusted manually or automatically by controller 104 using one or more valves. The PAW produced in the first period of time of using plasma reactor 110 may be stored for up to two days in a closed container such as storage tank 138. The water-rich nitrate is then stored for an optimum period to enhance nitrate production. For example, the fertilizer may be kept in an air-tight container with a lid for one week before being distributed to drip irrigation line 120. In embodiments, PAW may be mixed with non-PAW before distribution to drip irrigation line 120.
The nitrates (NO3−) content of commercially bought tomatoes, both medium tomatoes and cherry tomatoes were compared to tomatoes grown with tap water (control), commercial fish fertilizer and sustainable PAW fertilizer. As shown in Table 1 below, the nitrates content of tomatoes grown with sustainably manufactured fertilizer is comparable to or lower than the nitrates found in the other tomatoes tested.
Soil samples were tested prior to fertilizer application and mid-season, and the samples showed a decrease in nutrients after the growing season had begun. This could imply that there are some nitrates leaching from both the fertilized soils as well as the tap water cases. However, the amount of nitrates from the control case being more than the green fertilizer scenario could mean that the nitrates in tap water are less able to be absorbed directly by the plant after the season has begun than the tomatoes that were fed with test green fertilizer.
System 100 as disclosed herein solves the increasing need for fertilizer at a low cost while mitigating nitrogen pollution and carbon-dioxide emissions mainly associated with the traditional fertilizer manufacturing process. The system synthesizes nitrogen-based fertilizer from air and water on-site using low-temperature atmospheric air plasma powered by renewable energy sources such as solar panels and wind turbines. The transferred discharge plasma generated by the pin-to-water plasma reactor configuration operates at ambient conditions, making it suitable for compact, low-cost, and resilient embodiments suitable for fertilizer production on-site, where the plants need it. The generated plasma consisting mainly of ionized nitrogen and oxygen undergoes multiple reactions with water to produce nitrate and other auxiliary ionic species such as nitrite and ammonium. The system is integrated with the fertilizer storage tank, which enhances the production of more nitrate after the post-plasma reaction. Additionally, the system is modular and equipped with an on-demand delivery system easily adaptable to existing drip-irrigation systems, proving its adaptability, resiliency, and environmental benignity, leading to the decarbonization of fertilizer manufacturing. The technology's reliance on renewable energy sources such as solar and wind is environmentally friendly and sustainable.
Changes may be made in the above methods and systems without departing from the scope hereof. It should thus be noted that the matter contained in the above description or shown in the accompanying drawings should be interpreted as illustrative and not in a limiting sense. Herein, and unless otherwise indicated: (a) the adjective “exemplary” means serving as an example, instance, or illustration, and (b) the phrase “in embodiments” is equivalent to the phrase “in certain embodiments,” and does not refer to all embodiments. The following claims are intended to cover all generic and specific features described herein, as well as all statements of the scope of the present method and system, which, as a matter of language, might be said to fall therebetween.
| Number | Date | Country | |
|---|---|---|---|
| 63343545 | May 2022 | US |
