ENHANCED GEOTHERMAL

SYSTEMSWith Hydroshearing

CONVENTIONAL GEOTHERMAL SYSTEMS

When water is heated by the earth’s heat, hot water or steam is trapped in permeable and porous rocks under a layer of impermeable rock & form geothermal reservoir.

Traditional geothermal sources are systems where large quantities of hot water or steam can be tapped economically from permeable zones at less than 3500 meters for direct use or power generation.

Geothermal energy, in the form of heat, can be harvested by bringing hot water and steam trapped in rocks up to the surface. Steam-driven geothermal power plants have been producing sustainable, green energy for over 100 years.

DISADVANATGES It is only suitable for regions which have

permeable hot rocks below the earth and can produce steam over a long period of time.

The huge amounts of geothermal resources within the drillable depth are stored in the formations that are deficient in water or permeability.

Geothermal sites can run out of steam over a period of time due to drop in temperature.

Geothermal sites may contain some poisonous gases and they can escape deep within the earth, through the holes drilled by the constructors.

CONVENTIONAL GEOTHERMAL PLANT WORKING

ENHANCED GEOTHERMAL SYSTEMS

It’s a loop-cycle system that pumps water into bedrock to re-open and create fractures. The water is then naturally heated by heat down the earth’s surface.

Production wells are drilled at key intersecting points in the reservoir to pick up the now-hot water pumped from the injection well. Once the water reaches the surface again, it heats a fluid that creates vapor to drive turbine generators that create electricity.

HYDROSHEARING It’s to crack apart rocks to enhance the

transfer of heat to injected water to produce steam.

Using this we could get fractures where are no natural fractures already present.

The process squeezes open, by high pressure, water joints that would slip anyway and the slippage doesn’t have to be by much.

Because the rocks have rough surfaces, the cracks are propped open naturally and don’t close on top of each other when pressure goes back to least principal stress.

HYDROSHEARING

SEALED,. SLIPPING. SELF PROPPED

MULTI-ZONE EGS Reservoirs

Multiple sets of fractures created through one injection well itself.

AltaRock uses a patented thermally biodegradable polymer to seal off zones after stimulation.

Hydroshearing is then done in zones, or fracture planes, uphole.

After the zones are stimulated, the heated water eventually dissolves the polymer, largely into carbon dioxide and water.

MULTI ZONE SIMULATION

HYDROSHEARING v/s FRACKING

HYDROSHEARING FRACKINGo Higher Pressures to

initiate tensile fractures

o Opens the well widely.

o Requires proppants to hold the well open.

o Used in oil and gas industry.

o Chemically based fracking fluids.

Moderate pressure used.

To open small cracks of 1-2 mm.

No need of proppants to keep the well open.

Used in EGS. Water being pumped,

hence no groundwater contamination.

CURRENT EGS PROJECTS AltaRock, headquartered in Seattle, AltaRock

Energy, Inc. is a full-service geothermal energy technology and services company.

Google, in 2008 invested more than $10 million in the technology. Funding went to two companies, Alta Rock Energy and Potter Drilling, and two universities, Southern Methodist University’s Geothermal Lab and Stanford University, to reduce costs and expand range, and to create mapping to understand the size and extent of the energy resource.

EFFICIENCY Increasing the flow of hot water or steam three to

five times with multi-zone stimulation leverages those capital costs, and can decrease the cost of power produced by over 50%.

Single-zone EGS with 1 injection well & 2 production wells might produce of order 1.5 MW of power. Using multi-zone stimulation on the same 3 well layout would result in 10-15 MW of power production.

A five acre geothermal pad could support 3 injectors and six producers. In this scenario, a single-zone EGS could produce 5 MW of electricity on the five acre pad. Multi-zone EGS would produce 30-50 MW of electricity on the same pad.

ADVANTAGES OF EGS It can be applied to areas without permeable

rocks and naturally occurring fluids, making it feasible anywhere in the world.

The cost is highly reduced by the technique of hydro shearing creating multiple fractures through one injection well itself.

EGS emits little to no greenhouse gases. Most geothermal power plants use a closed-loop binary cycle power plant and have no greenhouse gas emissions

It has ability to satisfy base load electricity demand. Unlike intermittent renewable energy technologies, such as wind and solar power, EGS could provide a consistent electricity supply.

LIMITATIONS OF EGS Some induced seismicity is inevitable and

expected in EGS, which involves pumping fluids at pressure to enhance or create permeability through the use of hydro-shearing techniques.

The exploratory phases of a geothermal project are marked by high capital costs.

Water used for such plants are huge, and can use water equal required by 450 homes a day.

FUTURE TECHNOLOGY IN EGS

The use of supercritical CO2, instead of water, as the geothermal working fluid, might turn favorable, with further research.

CO2 can trigger greater power output minimized parasitic losses from pumping and cooling.

Also, it can minimise water use.

SCOPE IN INDIA

REFERENCES [1]. IGA-International geothermal association, http://www.geothermal-

energy.org [2] Green Chip Stocks,

http://www.greenchipstocks.com/articles/renewable-energy-capacities-bycountry/765

[3]. Anantha, A. and Chowhan P.L., Strategies for a nation-wide survey of renewable energy resource available in each village in India, Rural Energy Management”, Deep & Deep Publication, New Delhi., p.p.-2181-2186.

[4]. Energy Resources: Geothermal Power, http://www.darvill.clara.net/altenerg/geothermal.htm

[5]. “Strategic plan for the geothermal energy program,” U.S. Dept. of Energy, DOE/GO-10 098-572, 1998.

[6]. [Online]. Available http://www.eren.doe.gov/geothermal [7]. “Geothermal technologies today and tomorrow,” U.S. Dept. of

Energy, 1998. [8]. L. Lamarre, “Heating and cooling,” EPRI J., pp. 24–31, May/June,

1998. [9]. STANLEY R. BULL, “Renewable Energy Today and Tomorrow”,

Proceedings of the IEEE, VOL. 89, NO. 8, AUGUST 2001, p.p-1216-1226. [10]. Valgardur Stefansson, Reykjavik, Iceland, “Global Perpective on

Geothermal Energy”, IEEE-2011.

ANY QUERIES?