Devices and techniques relating to landfill gas extraction
Devices and techniques related to landfill gas extraction are disclosed. A technique for controlling extraction of landfill gas from a landfill through a gas extraction system is described. The method may include measuring a plurality of values indicating conditions associated with the landfill; computing, based at least in part on the plurality of values and on a model of the landfill, a predicted future state of the landfill; determining, based at least in part on the predicted future state of the landfill, one or more control parameters for one or more respective control devices configured to control operation of the gas extraction system; applying the one or more control parameters to the one or more respective control, and with the one or more control devices, controlling extraction of the landfill gas from the landfill based, at least in part, on the one or more respective control parameters.
1. A system for controlling extraction of landfill gas from a landfill via a gas extraction system, the gas extraction system comprising at least one vacuum source, well piping, and at least one well coupled to the at least one vacuum source through the well piping, the system comprising:
at least one sensor configured to measure characteristics of extracted landfill gas being extracted from the landfill, the characteristics of the extracted landfill gas including a concentration of one or more constituent gasses in the extracted landfill gas;
at least one flow control mechanism disposed in well piping and configured to control flow rate of landfill gas through the gas extraction system; and
a controller configured to:
determine a measure of concentration of nitrogen in the landfill gas being extracted from the landfill at least in part by using the at least one sensor; and
automatically control the at least one flow control mechanism based at least on the measured concentration of nitrogen in the landfill gas being extracted from the landfill at least in part by:
determining whether the measure of concentration of nitrogen is different from a target constant nitrogen concentration; and
automatically controlling the at least one flow control mechanism to change concentration of nitrogen in landfill gas being extracted from the landfill when it is determined that the measure of concentration of nitrogen is different from the target constant nitrogen concentration.
2. The system of claim 1 , further comprising a sensor configured to measure an ambient temperature outside of the gas extraction system, wherein the controller is further configured to:
obtain a measure of the ambient temperature outside of the gas extraction system at east in part by using the sensor; and
automatically control the at least one flow control mechanism based at least on the measure of the ambient temperature.
3. The system of claim 1 , further comprising a sensor configured to measure an atmospheric air pressure outside of the gas extraction system, wherein the controller is further configured to:
obtain a measure of the atmospheric air pressure outside of the system at least in part by using the sensor; and
automatically control the at east one flow control mechanism based at least on the measure of the atmospheric air pressure.
4. The system of claim 1 , wherein the controller is further configured to:
determine a target vacuum pressure in the well piping; and
automatically control the at least one flow control mechanism based at least on the target vacuum pressure.
5. The system of claim 1 , wherein the characteristics of the extracted landfill gas include a flow rate of the extracted landfill gas, and the controller is further configured to:
determine a measure of energy content of the extracted landfill gas using measurements of flow rate of the extracted landfill gas and concentration of methane in the extracted landfill gas obtained at least in part by using the at least one sensor;
determine whether the measure of energy content is different from a target energy content; and
automatically control the at least one flow control mechanism to change energy content of landfill gas being extracted from the landfill when it is determined that the measure of energy content is different from the target energy content.
6. The system of claim 5 , wherein the controller is further configured to automatically control the at least one flow control mechanism to change energy content of the landfill gas being extracted from the landfill at least in part by controlling the at least one flow control mechanism to change a concentration of methane in the landfill gas being extracted from the landfill.
7. The system of claim 6 , wherein controlling the at least one flow control mechanism to change the concentration of methane in the landfill gas being extracted from the landfill comprises controlling the at least one flow control mechanism to decrease the concentration of methane in the landfill gas being extracted from the landfill.
8. The system of claim 6 , wherein controlling the at least one flow control mechanism to change the concentration of methane in the landfill gas being extracted from the landfill in a comprises controlling the at least one flow control mechanism to increase the concentration of methane in the landfill gas being extracted from the landfill.
9. The system of claim 5 , wherein the at least one sensor is configured to measure the flow rate of the extracted landfill gas at least in part by measuring a pressure differential across a restriction to the flow of gas through the at least one flow control mechanism.
10. The system of claim 1 , wherein the at least one flow control mechanism comprises a valve, and wherein the controller is further configured to automatically control the at least one flow control mechanism at least in part by closing the valve to a greater degree or opening the valve to a greater degree.
11. The system of claim 1 , wherein the controller is further configured to automatically control the at least one flow control mechanism to establish or maintain compliance of the gas extraction system with local, state, and/or federal regulations.
12. The system of claim 1 , wherein the controller is further configured to automatically control the at least one flow control mechanism at least in part by using electrical power data from a power plant receiving landfill gas being extracted from the landfill.
13. The system of claim 1 , wherein the controller is further configured to automatically control the at least one flow control mechanism to meet a power generation capacity of a power plant that is receiving landfill gas being extracted from the landfill.
14. The system of claim 1 , wherein the controller is local to the gas extraction system.
15. A method for controlling extraction of landfill gas from a landfill through a gas extraction system, the gas extraction system comprising at least one flow control mechanism, the method comprising:
obtaining, using at least one sensor, measurements of characteristics of extracted landfill gas being extracted from the landfill, the characteristics of the extracted landfill gas including a concentration of one or more constituent gases in the extracted landfill gas;
determining a measure of concentration of nitrogen in the landfill gas being extracted from the landfill at least in part by using the at least one sensor; and
automatically controlling the at least one flow control mechanism based at least on the measured concentration of nitrogen in the landfill gas being extracted from the landfill at least in part by:
determining whether the measure of concentration of nitrogen is different from a target constant nitrogen concentration; and
automatically controlling the at least one flow control mechanism to change concentration of nitrogen in landfill gas being extracted from the landfill when it is determined that the measure of concentration of nitrogen is different from the target constant nitrogen concentration.
16. The method of claim 15 , further comprising:
obtaining, using a sensor, a measure of ambient temperature outside of the gas extraction system; and
automatically controlling the at least one flow control mechanism based at least on the measure of the ambient temperature.
17. The method of claim 15 , further comprising:
obtaining, using a sensor, a measure of the atmospheric air pressure outside of the system; and
automatically controlling the at least one flow control mechanism based at least on the measure of the atmospheric air pressure.
18. The method of claim 15 , further comprising:
determining a target vacuum pressure in the well piping; and
automatically controlling the at least one flow control mechanism based at least on the target vacuum pressure.
19. The method of claim 15 , wherein the characteristics of the extracted landfill gas include a flow rate of the extracted landfill gas, and the method further comprises:
determining a measure of energy content of the extracted landfill gas using measurements of flow rate of the extracted landfill gas and concentration of methane in the extracted landfill gas obtained at least in part by using the at least one sensor;
determining whether the measure of energy content is different from a target energy content; and
automatically controlling the at least one flow control mechanism to change energy content of landfill gas being extracted from the landfill when it is determined that the measure of energy content is different from the target energy content.