The Integrated Geothermal Tree Power Plant (IGT) is a novel giant geothermal radiator with only one single well to extract large scale geothermal energy from low, medium or high geothermal resources specially from the wide abundant low thermal conductive sedimentary rocks, regardless to rock’s permeability, porosity or formation pressure.
The system is achieving these without any contamination from rocks trapped fluids, In a low-cost and small surface footprint theoretically at around 80 % of the world.
IGT is using a novel well completion design – for integrating many long horizontal laterals in one single closed production/injection loop cycle in order to circulate large amounts of working fluids to optimize geothermal energy extraction from the host rock.
The IGT Concept
IGT concept is created based on integration of five main effective elements
1- Long Extended Horizontal Laterals
IGT uses long horizontal laterals to ultimate exposed interval and to increase heat extraction surface area of any hot rocks which enable the system to use huge amount of working fluid to optimize geothermal energy extraction and to overcome the limitation of sedimentary rocks low thermal conductivities which is not utilized yet in existing deep geothermal technologies.
IGT is uses laterals casing pipes as a loop to conduct heat from surrounding hot rocks to the circulated working fluid inside, which is advantageously enables to place laterals at any hot sedimentary rocks regardless to their permeability, porosity or formation pressure without being bounded by the rare geothermal reservoirs (high permeable / high pressure reservoirs) as traditional geothermal technologies, and to avoid the expensive /earthquakes trigger/high uncertainty dry rock’s fracking process at Enhanced Geothermal Systems (EGS) technology and to insure complete sealing/isolation from the surrounding rocks fluids.
Different deviated types of laterals also can be used according to geology nature, rocks heat conductivity and formations pressure regimes.
2- IGT Working Fluid
Using the thermodynamically-suitable main working fluid to optimize energy extraction from low and medium potential geothermal resources and especially from the untouched low conductive heat sedimentary rocks.
At low temperature resources IGT is using low boiling cheap fluid or refrigerant (such as ammonia, Butane, Iso-pentane or supercritical CO2) to be the main working fluid instead of water because of the following reasons. Low boiling fluids produce higher vapor pressure than water vapor pressure at the same temperature in the range of 40Co – 270Co degree.
For example at 120 Co degree at atmospheric pressure: Water vapor pressure is less than 2 bars only while most of those fluids will be in supercritical vapor phase with high vapor pressure in range go +30 -100 bars.
The circulation rates of low boiling fluids are 3-4 times faster than water/steam as they are heated up/ evaporated/ reached at surface quicker than water due to their relative low specific heat
Low boiling fluids/refrigerants are much less cooling surrounding rocks than water as they need less heat amount to evaporate than water due to their relative low specific heat.
Iso-Butane / Butane as the main working fluid for IGT
IGT is using Iso-Butane/Butane to be the main working fluid to for the following reasons.
- It is low boiling point and low supercritical temperature-pressure points are suitable for extract heat energy from low geothermal resources to surface.
- It is the highest efficient fluid to convert thermal energy to electrical energy through ORC turbines.
- It is many times less cooling for surrounding rocks than water due to its relative low specific heat which means longer time for thermal drawdown of the host-rock.
- It has no any corrosive effect for casing pipes and all surface equipment.
- It has no dangerous environmental impact.
- Cheap price
3-Novel Well Completion
IGT novel well completion is designed for integrating many long horizontal laterals in one single closed production/ injection loop cycle in order to circulate large amounts of working fluids to optimize geothermal energy extraction.
4- Enhancing Heat Conductivity of Surrounding Rocks
Enhancing Heat Flow Optimization Process (HFOP) is a process achieved only in low heat conductive rocks by pumping and injecting large amounts of high thermal conductive cement , mud slugs or foam in multi-stages to invade the permeable sedimentary rocks deeply and fill rocks pore spaces, natural fractures or artificial hydraulic fractures, in order to enhance target rocks thermal heat flow around the laterals to increase energy harvesting and to overcome the low thermal conductivities limitations of the surrounding sedimentary rocks and to utilize large abundant geological sections of low thermal conductive sedimentary rocks.
The cement/foam/mud slugs containing a considerable percentage of high heat conductive materials such as very fine or Nano size graphite powder, pyrite, iron powder or any suitable material.
5- Injection-production without electrical power
Rather than traditional geothermal technologies that consume +20% up to 40% from the net generated electricity in production injection cycle, IGT is designed to work without any electrical power for injection or production cycle as the working fluid is injected by the action of gravity force and hydrostatic pressure (as shown by green arrows) while the vapor production raised to surface by thermosiphon action and evaporization pressure (as shown black arrows) .