WO2008034205A1

WO2008034205A1 - Collecting and dehumidifying system of methane gas from deep waters of lakes, dams or rivers, applicable to hydroelectric plants, water catchment for cities, metropoli, irrigation canals

Info

Publication number: WO2008034205A1
Application number: PCT/BR2006/000199
Authority: WO
Inventors: Imai Takeshi
Original assignee: Imai Takeshi
Priority date: 2006-09-22
Filing date: 2006-09-22
Publication date: 2008-03-27

Abstract

Invention Patent of a 'COLLECTING AND DEHUMIDIFYING SYSTEM OF METHANE GAS FROM DEEP WATERS OF LAKES, DAMS OR RIVERS, APPLICABLE TO HYDROELECTRIC PLANTS, WATER CATCHMENT FOR CITIES, METROPOU, IRRIGATION CANALS AND WATER TRANSFER', characterized for removing and collecting the methane gas that is dissolved in deep waters through depressurization and collection with dehumidification and purification, if necessary, and subsequent delivery for consumption.

Description

"COLLECTING AND DEHUMDIFYING SYSTEM OF METHANE GAS FROM DEEP WATERS OF LAKES, DAMS OR RIVERS, APPLICABLE TO HYDROELECTRIC PLANTS, WATER CATCHMENT FOR CITIES, METROPOLI, IRRIGATION CANALS AND WATER TRANSFER". This Application for Patent of Invention, describes a new "COLLECTING AND

DEHUMIDIFYING SYSTEM OF METHANE GAS FROM DEEP WATERS OF LAKES, DAMS OR RIVERS, APPLICABLE TO HYDROELECTRIC PLANTS, WATER CATCHMENT FOR CITIES, METROPOU, IRRIGATION CANALS AND WATER TRANSFER", whose purpose is that of creating a new source of gas power aimed at increasing the production of electric power in hydroelectric plants or allowing for a source of thermal power and, above all eliminating the release of methane gas in the environment, insofar as methane is a strong gas that causes the greenhouse effect, which is 21 times more harmful than the CO2 when released into the atmosphere. The process removes the methane gas from deep waters from lakes, dams or rivers, by depressurization; it was initially created to be applied in hydroelectric plants, but it can also be used in water production and suppiy plants in major cities, metropoli, irrigation canals or natural rivers and lakes to draw more thermal power. The initial description of the process shall address only the aspects concerning the collection of the methane gas from hydroelectric plants as an example, whereas the other applications shall remain underlying to the other uses mentioned in the Patent's heading, which are similar, inasmuch as the same basic principles of this Patent are applied thereto: the depressurization of deep waters and collection of the so released methane gas. The electric power generation turbines in dams of hydroelectric power plants produce rotary mechanical power from the pressurized water accumulated in these plants' dams. As they are depressurized in the turbines and spillways, these waters release significant volumes of methane gas which was dissolved in the pressurized water existing in the depth of rivers and dams, together with low rates of carbon dioxide gas, both causers of the greenhouse effect if released into the atmosphere. CO2 is dissolved in low rates, but the methane gas ChU is dissolved in the pressurized waters of rivers in meaningful amounts. Whereas the methane gas resulting from the above decomposition above the water and in the forest's sink holes is low, most part of the decomposition of the CO2 takes place above the water level. The methane gas' absorption capacity in water solution is substantially increased upon pressure increase. The gases in water solution remain "retained" by water pressure in a manner similar to that of a bottle of soda pop or mineral water with CO2 gas whose lid, when opened, depressurizes and releases the CO2 gas dissolved as bubbles in the liquid. In the depressurization of water in the turbines and spillways, the methane gas (ChU) is released into the atmosphere together with a small portion of the carbon gas (CO2) that is similarly dissolved.

Methane is formed by decomposition of trees and roots that remained from the formation of the dams, and the methane resulting from the decomposition of the soft water vegetation and trees roots that decompose under the subsoil of the entire hydrographic basin of a river, insofar as the methane released from a decomposed root underneath the soil level is absorbed by the subsoil water, with which it solutes and is then carried by the waters through the underground water tables that flow into the rivers. There is little release of methane on the surface of the earth, because decomposition takes place especially in the presence of water. Additionally, with the leaves, branches, fishes and other animal and vegetable organic substances that decompose in the water and in the subsoil of hydrographic basins and are taken into rivers through the surface and groundwater tables of rivers and dams. Thus, meaningful volumes of methane gas are continuously and permanently released by turbines and spillways during depressurization to generate mechanical power by turbines, and transformed by generators into electric power. Methane production in a new dam or plant is larger in the first decades of its operation because of the filling out of the dam among a major volume of flooded biomass, but the subsequent release of methane stabilizes after some decades, especially because of the underground collection of methane gas fed by all the decomposing tree roots throughout the hydrographic basin, whereas it is dissolved and carried by underground water tables that feed the rivers and reach dams and reservoirs.

The absorption capacity of gases in solution by pressurized liquid - particularly of methane gas in water - is very high and increases substantially with depth as a result of pressure increase. The hydroelectric plants' turbines and spillways remove the water to generate power from depths that are enough to release meaningful amounts of methane gas retained by the water column. Here we have some examples: in year 1990, thirteen years after it was filled, the Curua-Uma dam (State of Para), for example, released 3.7 times more gases of greenhouse effect equivalent to CO2 than what would have been released generating the same amount of electric power through the burning of oil. The most significant portion of such gas, however, is methane, which could be used to generate more thermoelectric power or to produce thermal power by combustion in industrial furnaces and steam generators in nearby regions in order to distribute power through pressurization or pipes, or for use in vehicles in super-pressurized systems, or even used as raw material for the chemical industry, which would, at the same time, be reduced, or it could simply be burned so as to transform it into water steam and CCh, thus meaningfully reducing the damages of the greenhouse effect in the Planet and generating a new source of clean power at very competitive costs.

5 Likewise, plants for the treatment of water for consumption in metropoli and big cities that take their water from deep reservoirs or rivers may as well previously remove the methane gas from the water by simply installing the methane gas collecting apparatuses that are object of this Invention Patent and use them with the same aforementioned purposes, thus preventing its release into the atmosphere and io contributing to reduce the greenhouse effect. Finally, in certain circumstances, there may be plants specifically aimed at generating methane gas removed from deep waters of lakes and rivers through depressurization and collection. The so collected gas could generate electric power to bomb part of the water for purposes of irrigation and transfer to other regions.

15.. According to studies on the Hydroelectric Plant of Tucurui carried out by

Professor Emilio La Rovere, expert in energy and gases of greenhouse effect, from Universidade Federal do Rio de Janeiro [Federal University of Rio de Janeiro], in sink holes, the total impact of emissions of the different gases (ChU and CO2) that cause the greenhouse effect in 1990 - six years after the closing of the reservoir -equals amounts that range from 7 to 10.1 million tons of carbon equivalent to CO2 (in that 7 million would be the low rate and 10.1 million the high rates). Of such emissions, methane ChU, participates with 75% in the high rate and 64% in the low rate; the rest

5 of the emissions is of CO2.

The dimension of the emissions by Tucurui can be understood because it is comparable to that which can be recorded in the total emission in the metropolitan area of Sao Paulo. According to La Rovere, in 1990, Brazil emitted 53 million tons of carbon from fossil fuels. Therefore, the emission of 7 to 10.1 million tons of carbon

10 equivalent to CO2 of Tucurui in 1990 represented from 13% (high rate) to 19% (low rate) of the emission of fossil fuel produced at that time by the Country's population (170 million inhabitants). The emission by Tucurui was 1.3 times (high rate) and 1.9 times (low rate) larger than that of the fossil fuel burned by the 17 million inhabitants of the metropolitan area of Sao Paulo. Thus, only the methane released in Tucurui would

15.. cause a greenhouse effect equal to or higher than that of all the fossil fuel consumed in the metropolitan area of Sao Paulo.

A small portion of the emissions of methane and a considerable portion of the emissions of carbon gas in Tucurui take place above the level of water, but the most significant portion of methane emissions take place below the level of water, in turbines and spillways. The emission of methane below the level of water is 70% over the total emissions in the high rate and 57% of methane in the low rate. The decompositions and emissions of CO2 below the level of water reach only 0.30% in the

5 high rate and 0.43% in the low rate. Thus, we can state that the more meaningful emissions below the level of water are those of methane, and most of this methane leaves the turbines and spillways during depressurization. At this point, we would like to restate that the aforementioned percentage figures, taken from the works of Professor Emilio La Rovere, are expressed in terms of carbon equivalent to CO2.

10 The explanations above show that the reservoirs of hydroelectric plants and those for the removal of water for treatment and consumption in major cities and metropoli are the ideal places to collect the methane gas that has been released into the atmosphere and is unnoticed by experts. In addition to being a clean fuel, methane gas is the major causer of the greenhouse effect when released into the

15.. atmosphere, and affects precisely 21 times the greenhouse effect than the CO2, whereas this gas can be collected and used to generate heat or to transform it into electric power of thermal origin, or even as raw material in the chemical industry to produce other supplies such as liquid fuels. This is the main purpose of this Invention Patent.

We have created a system to collect-dehumidify methane gas originated from water depressurization in reservoirs, dams and rivers, aimed at capturing the methane

5 gas stored by nature originated in the deeper parts of rivers, lakes and water reservoirs. As we have described, this system can be adapted to facilities such as hydroelectric plants, but treatment plants of water for major cities or metropolis can also benefit from the use of our process. The so collected methane gas allows for a clean flame and can be burned only to prevent the greenhouse effect or to generate heat for the

10 production of electric power, to feed industrial furnaces, greenhouses and steam generators, which can activate water pump stations, whether pressurized or piped, for distribution for household purposes or even for vehicle use,- when super-pressurized. Its use helps to reduce substantially the greenhouse effect in the Planet, insofar as the amounts that can be generated are surprisingly large.

15. The practical feasibility of the "COLLECTING AND DEH U Ml Dl FYI NG SYSTEM

OF METHANE GAS FROM DEEP WATERS OF LAKES, DAMS OR RIVERS, APPLICABLE TO HYDROELECTRIC PLANTS, WATER CATCHMENT FOR CITIES, METROPOLI, IRRIGATION CANALS AND WATER TRANSFER" can greatly vary in its practical execution form, depending on the place, the existing facilities, water dimensions, volumes and depths from where the methane will be extracted, and the purpose at which the so extracted methane gas is aimed, but it is characterized by a cover preferably made of transparent plastic, forming a large hood or dome to collect the gas or water steam that bubbles in the depressurized water such as in water spillways of a hydroelectric plant. Such hood may be sealed by the plant's downstream water itself in order to prevent air from entering the system, insofar as the system is aimed at collecting exclusively methane gases (in large amounts), carbon dioxide (in small amounts) that bubble in the depressurized water as a result of its release into the atmospheric pressure. A significant volume of water steam and droplets is collected in the depressurization process; therefore, a dehumidification procedure is advisable.

In order to better understand the process but without limiting it to the exemplified case, we mention an instance for application, the project applied into a typical hydroelectric plant whereby:

Figure 1 shows, through a cut, a hydroelectric plant's reservoir, a Kap/an-type turbine and the electrical generators, the penstock for collection and discharge of the water into the spillways where the depressurized waters are sent downstream the plant after having transferred the potential hydraulic power to generate electric power.

Figure 2 shows the same cut as in figure 1, magnified only downstream, now equipped with a system of hoods and pipes for the collected methane gas, CO, and water steam, highlighting the sealing system downstream at water level to prevent aspiration or penetration of atmospheric air in the process.

Figure 3 shows a deflector system that can be installed upstream the reservoir area to ensure collection of the deepest water, with the purpose of increasing the collection of the methane gas. Figure 4 shows a methane gas humidifying and purification system to reduce the presence of water steam in the process, leaving the methane gas dry, without water steam. A basic and cost-efficient decantation takes place through simple storage and precipitation of steam, but a water steam condensation grid that withdraws the condensed liquid water can be more effective. In this phase, we can also connect a system to separate CO2 gas, if necessary, through membrane separators, a technology already available in the market. We would like to remind, however, that the CO2 participates with low volumes, and this decision should be made .with basis on cost-benefit or technique, depending on the need for the use of the methane.

In figure 1 , the concrete dam (1) retains the water (6) of a river to a level (2) that

5 flows through a protection grid (7) through a canal (3) to a Kap/an-type hydraulic turbine (4), which converts the water pressure (6) by activating through rotation the electric power generator (5), which produces electricity from the water (6) pressurized by the level (2), and makes the water run downstream (6), flowing into a discharge (8) through the spillway (9) returning to the river level (10). The generators (5), insofar as

10 usually a hydroelectric plant has many of them, are arranged on a parallel manner in the power house (11) of the hydroelectric plant. The methane gas, together with the small amount of CO2 and water steam comes out the water through bubbles (6) in the water flow + methane bubbles and carbon dioxide (8), which are released because of water depressurization in the spillway (9) and is pointed out in the figure by the arrows

15. (12) , thus joining the atmospheric air (13).

Figure 2 shows in detail the downstream portion of the hydroelectric plant, with the dam (1), the discharge canal (3) of the water (6) that comes out in a bubbling flow (8) whereby the bubbles contain methane gas and carbon dioxide that were formerly dissolved in the water (6) as a result of high pressure. The gases that come out from the area pointed out by the arrows (12), are then collected by the dome (14), which can be built in transparent plastic material structured by a metal framework and whose lower portion (15) is immersed in the level (10), in order to prevent the inflow of

5 atmospheric air (13). The gases released by the discharge flow (8) and that come out through the arrows (12), are then collected by the dome (14) and sent through the collecting pipe (16) to a dehumidifying, purification and pressurization station, as follows:

Figure 3 shows in detail the plant's upstream portion, where the concrete dam

10 (1), the canal's entrance (3) and the grid (7) are shown in more detail so as to explain the deflector (27), which may be optionally installed and may be fastened on one of the sides of the dam itself (1) and on the other side by a bar or support cable (28) and can also have an additional auxiliary deflector (29) with the purpose of directing the aspiration of the water that feeds the Kaplan turbine (4) with deeper waters in order to

15. draw more methane gas, inasmuch as the higher rates of methane are in the lower portions of the river or reservoir. With the movement of the deflectors (27) and (29), we can draw more or less methane, thus allowing for flexibility in the production to meet the demand. Figure 4 shows a unit (22) for dehumidification, purification and pressurization of methane gas for consumption. The gas flow (12) collected in the hood (14), is sent through piping (16) as far as the unit (22) and then homogeneously distributed by the deflectors (17) to the water condensation unit through cooling louvers (18) that make the condensation of the water steam to the necessary or desired level. The so condensed water flows through the outlet (20). The air flow, now drier (12), can pass through the unit (19) which separates the CO2 through a membrane technology that is already available in the market. This phase is optional, insofar as the rate of CO2 is very low, whereas it can be used or not, depending on the cost-benefit of the treatment or in order to produce a purer methane gas on account of technical needs. The final phase is the delivery of the methane gas for consumption, which may be in low pressure through a fan (23), for use and burning in nearby areas, such as in a set of a steam generator connected to a turbine and an electric power generator. In the case of delivery to further locations, for home and/or industry consumption, a compressor (24) can send the gas to the consumption sites. For the use in vehicles, it would be necessary to use super-compressors in the distribution points. The entire network needs gas storage tanks to regulate production and demand. The withdrawn volume can also be adjusted by the deflectors (27) and (29), as in Figure 3. Figures 1 through 4 and our explanation show an example of practical application of the concept of the object of this invention patent "COLLECTING AND DEHUMIDIFYING SYSTEM OF METHANE GAS FROM DEEP WATERS OF LAKES, DAMS OR RIVERS, APPLICABLE TO HYDROELECTRIC PLANTS, WATER CATCHMENT FOR CITIES, METROPOLI, IRRIGATION CANALS AND WATER TRANSFER". The practical execution of the plan may change according to several construction details, depending on the type of plant, turbine, or use, but the essential is to capture the methane gas after water depressurization and precipitate it without pressure through a shower and collect it through a collecting system that is not in contact with air, as shown in the example.

The amount of methane available in the bottom of a lake, reservoir or river can be analyzed and calculated by drawing samples of water in several levels of depth. A technology for specialization to operate the process in an accurate and cost-effective manner must be developed in practical terms by building pilot plans and burning the collected methane in order to analyze the actual production and the operating applicability and actual yield of the process object of this Invention Patent and improve it in order to achieve the maximum efficiency in the cost-benefit ratio, and to achieve the financial advantages resulting from the Kyoto Protocol, thus opening a new a major scientific possibility to reduce the greenhouse effect in our Planet, as we concurrently generate a major volume of thermal power, which is increasingly expensive as time passes by. These topics justify this Application for Patent Invention.

Claims

"COLLECTING AND DEHUMIDIFYING SYSTEM OF METHANE GAS FROM

DEEP WATERS OF LAKES, DAMS OR RIVERS, APPLICABLE TO

HYDROELECTRIC PLANTS, WATER CATCHMENT FOR CITIES, METROPOLI, IRRIGATION CANALS AND WATER TRANSFER", characterized for removing the methane gas that is dissolved and retained in deep waters through depress u rization and collection of such gas by means of collecting hoods in air-free environment, whereas the gas can be subsequently burned or treated for dehumidification, CO2 separation, and sent for application in combustion, or chemical industry purposes.

2. "COLLECTING AND DEHUMIDIFYING SYSTEM OF METHANE GAS FROM DEEP WATERS OF LAKES, DAMS OR RIVERS, APPLICABLE TO HYDROELECTRIC PLANTS, WATER CATCHMENT FOR CITIES, METROPOLI, IRRIGATION CANALS AND WATER TRANSFER", characterized for preventing the methane gas depressurized to generate electric power or other applications resulting from its depressurization from being released into the atmosphere in order to help prevent meaningful increase of the greenhouse effect.

3. "COLLECTING AND DEHUMIDIFYING SYSTEM OF METHANE GAS FROM DEEP WATERS OF LAKES, DAMS OR RIVERS, APPLICABLE TO HYDROELECTRIC PLANTS, WATER CATCHMENT FOR CITIES, METROPOLI, IRRIGATION CANALS AND WATER TRANSFER", whose characteristic is that upon removal of the methane gas dissolved and retained in deep waters, it provides a clean and alternative source of thermal power for mankind to use in a time when oil and natural gas-based thermal powers have been depleting and thus, their prices are quickly increasing.

4. "COLLECTING AND DEHUMIDIFYING SYSTEM OF METHANE GAS FROM DEEP WATERS OF LAKES, DAMS OR RIVERS₁ APPLICABLE TO HYDROELECTRIC PLANTS, WATER CATCHMENT FOR CITIES, METROPOLI, IRRIGATION CANALSAND WATER TRANSFER" characterized for removing the methane gas that is dissolved and retained in deep waters of lakes, rivers and dams through depressurization, which allows for the achievement of a new clean thermal power: the methane gas in countries and areas that have natural rivers and lakes.