Electric Vehicles In An Electric-Centric World- Part 8- National Security

AVAILABILITY/RELIABILITY: NATIONAL SECURITY ENHANCEMENT

One huge advantage of employing a binary geothermal power system over a direct water-vapor system [dry steam or flash steam system] is that a binary system is not limited to near-surface thermal zones where the reservoir water is extremely hot, such as those zones that are found in the western United States [e.g., the "Geysers, located in California] or other "hot zones" near the "Ring of Fire".

ENVIRONMENTAL BENEFITS - RENEWABLE/SUSTAINABLE

The environmental benefits of binary geothermal power are also positive. A binary geothermal system is considered to be a "closed loop" system. Because this type of system is "closed", none of the fluids [hot water and "working"] are exposed to the environment. Therefore, this system does not discharge any greenhouse gases [carbon dioxide, sulfur dioxide, nitrous oxide] or other harmful substances into the atmosphere. Any such discharges are negligible at best when compared to the atmospheric release of noxious gases that are created when fossil fuels are used as the source of power to generate electricity. A binary deep well geothermal system also maintains a very small "footprint" when compared to the amount of electricity that it can generate. When the footprint of a binary geothermal power plant is compared to the foot print created by large-scale solar power and wind power [both require large surface areas and proper siting to gather their source of energy], binary geothermal's foot print is insignificant. With a binary geothermal system, the size of the plant is the only space that is used. Therefore, disruption of the surrounding geographic area and damage to the environment is minimized.

Another key advantage of binary geothermal power: with proper management reservoir depletion can be eliminated by calibrating the system so that the injection well continuously replaces the same amount of water that is withdrawn to operate the turbine. This process allows re-injected "spent" [cold] water to reheat in the deep reservoir at the same rate that the reheated reservoir water is withdrawn and pumped back up to the plant. A closed system exists in equilibrium. With continuous utilization techniques, subterranean strata pressures can be maintained so as to limit potential surface subsidence. Concerns about water draw down caused by ancillary evaporation that might occur in an open system are likewise negated in a closed system.

Another advantage of drilling into deep zones: the reservoir to be created will usually be situated far below ground water resources. Therefore, the risk of groundwater contamination caused by pollution from materials trapped in the sediment/rock layers within the reservoir system can be effectively managed. With proper cementing and encasement of the boreholes and production/injection wells, this potential source of contamination can be significantly minimized if not avoided completely. Drilling techniques presently used in petroleum exploration and extraction share a similar concern and may provide a shared solution [i.e., appropriate well casings]. Moreover, some "pools" of oil are located within areas that are close to near-surface aquifers. The risk of contamination of ground water in this situation is significantly greater with oil drilling than with deep well drilling. Contamination with mineralized reservoir water is the greatest threat posed by EGS whereas contamination with raw crude is the greater threat posed by oil production.

Of course, there are problems associated with the development of geothermal energy, as with all forms of energy. A word about a few of the important ones: (1) subsidence; (2) induced seismicity [earthquakes]; (3) thermal depletion.

Subsidence. Subsidence occurs when the land above the reservoir site sinks due to a loss of substrate structure and/or hydrostatic pressure. However, given the anticipated depths at which a reservoir will be created in an EGS project, and with proper construction and operation of the facility, this problem and its adverse effects can be minimized. To do so, the reservoir must be properly managed; the operator must inject the same amount of cool water into the reservoir that it extracts to produce hot water to generate electricity. By injecting the same amount of water that is extracted, the operator maintains a static geologic balance, and the chance of subsidence is significantly mitigated if not eliminated altogether. This unfortunate event is also experienced by the petroleum industry when it extracts oil from subterranean "pools". When oil is pumped from an underground reservoir the countervailing subterranean pressure that "buoys" the strata above is lost, and this loss of competing pressure causes the surface above to collapse.

Induced Seismicity. Here, micro earthquakes occur and are caused by ["induced"] the activities which create the deep reservoir. Introduction of extremely high hydrostatic pressures into the deep strata to create the fracture zone/reservoir is the culprit. However, because the wells are drilled at such great depths, and the reservoirs consume relatively small geographic zones, these earthquakes are mostly imperceptible and cause no outward damage. The overlying substrate and surrounding earth act as a buffers; they absorb the energy produced by the fracture within the fault zone before it can cause damage at the surface. Once the thermal reservoir is created, the risk of induced seismicity can be minimized by maintaining the thermal reservoir at equilibrium with a constant pressure [i.e., water removed = water injected].

Induced seismicity should be considered an acceptable risk, not only in terms of incidence of occurrence but in terms of potential damage. Proper monitoring and site development can minimize this risk and the associated hazards to a point of insignificance. And, if geothermal power bears this risk, so does underground coal extraction. Certain mining techniques, including underground blasting, may induce seismic events. Sometimes mine-induced seismicity is associated with "coal bumps", otherwise referred to as "bursts", "outbursts" or "bounces". This phenomenon involves the sudden release of geographic strain energy due to underground mining activity, which results in the expulsion of coal from a seam in a catastrophic manner. [see, < >http://www.cdc.gov/NIOSH/mining/pubs/pdf/cmsab.pdf]. Therefore, this risk is a "wash".

Thermal Depletion. This situation occurs when the hot water contained within the thermal reservoir is extracted through the production well at a rate that is faster than the spent [cooled] water used to heat the working fluid in the binary system is returned to the thermal reservoir via the injection well to be reheated by the surrounding hot rock which surrounds the thermal reservoir. However, with diligent adherence to proper operation, whereby the rate of water removal [thermal discharge] is equal to the rate of water injection [thermal regeneration/recharge] within the thermal reservoir, this problem can be totally eliminated. The EGS plant can therefore operate in perpetuity as a "renewable" and sustainable operation and as long as the earth's core produces sufficient heat via radioactive decay.

Other considerations, too specific and technical for analysis and discussion here, include: scaling [mineral build-up in the system caused by deposits of dissolved minerals within the reservoir that crystalize when the fluid becomes fully saturated]; permeability of the reservoir substrate and flow rate through the reservoir and up toward the surface [i.e., maintenance of hydrostatic pressure caused by overlying strata - the same pressure that causes the "gusher" when drilling for oil and allows water and magma to flow upward to the earth's surface]; thermal "evaporation" [where convection from the production well transfers heat to cooler surrounding substrate while the heated water flows upward to the earth's surface, resulting in a loss of the thermal energy that is used to heat the working fluid within the heat exchanger, thereby depressing the overall efficiency of the system].

In sum, EGS is a much simpler, more efficient, and potentially cheaper and vastly more productive system than one based on "carbon sequestration", which is nothing more than a "pollute first, clean up and hide later" approach.

FEASIBILITY

The process of generating electricity from EGS is already clearly understood. Present drilling technology allows for some utilization of this method to generate geothermal electricity today. Making EGS work on the scale needed to power millions of electric vehicles, however, will require a monumental increase in investment, additional research and concerted government action. Techniques now employed and technologies presently known can help improve the economics of EGS. For example, stepwise development can be used. Here, production from a thermal field is initiated as soon as the first productive well is drilled and reservoir created. Thereafter, any additional production comes on line as soon as practical. Moreover, multilateral drilling technology [branched or fingered wells] exists and this technology can be employed to create more productive reservoirs at depth. The goal: achieve "linear" drilling where the costs incurred to drill deep wells [+3 miles] become linear with depth. Other advanced technologies, such as flame-jet thermal spallation and water-jet cavitation, are waiting to be exploited.

As we move forward along this road towards energy self-sufficiency, additional anticipated advances in drilling technology and techniques will enable developers to obtain greater access to progressively deeper and hotter zones underlying all parts of the United States, thus progressively reducing the cost to gain access to these deeper thermal zones. Consequently, the overall capital costs needed to develop EGS will become continually lower over time, thereby reducing the cost per kWH. Ongoing programs highlight this anticipated future. One such program was established by the Massachusetts Institute of Technology [i.e., Advanced Drilling and Excavation Technologies - known as "NADET"]. M.I.T.'s was succeeded by the Department of Energy's own program [Geothermal Advanced Drilling System - known as "GADS"]. The DOE also maintains a "Deep Trek" program which studies developing methods and technologies that have the potential to make drilling into deeper zones more feasible, and more economical/less expensive. Presently, drilling to depths of three miles is a routine endeavor. Drilling to depths of five miles has been proven feasible as evidenced by Chevron's "Jack 2" rig in the Gulf of Mexico.

A new system called "IntelliPipe" is on the cusp of wide-spread commercial application. In a nutshell, this system uses drilling pipes which contain computer sensors that collect data at depth from downhole locations while drilling and allows that data to be transmitted back to the surface in real time, where the data may be analyzed. Thus, prospectors will know with greater precision, the temperature of the substrate at depth while drilling. Such vital information will allow drillers to more precisely identify the location and configuration of hot zones thereby improving their ability to develop productive subterranean reservoirs. In the future, more advanced sensors may be able to ascertain the chemical and physical composition and porosity of the substrate. The end result provides the opportunity to develop more sophisticated drilling techniques, including slant or horizontal/directional drilling which may be employed to create a porous reservoir system instead of using hydrostatic pressure to accomplish the same task.

In sum, deep drilling is already viable, albeit not on the scale necessary to provide sufficient electricity to make wide scale use of pure electric cars a short term reality. With advances in technology, we will be able to drill deeper still, thereby providing us with the means to mine heat in the quantity that is needed to achieve an electric-centric automotive future.

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