Electric Vehicles In An Electric-Centric World- Part 7- Geothermal

GEOTHERMAL - HEAT MINING

ENHANCED ["ENGINEERED"] GEOTHERMAL SYSTEMS/HOT DRY ROCK

Not to despair. There is one true alternative solution to this complex problem. The answer lies with deep-well [hot rock] enhanced binary geothermal power systems using the heat source that lies beneath our feet. Generally, as a well is drilled deeper into the earth's crust, and the closer it gets to the earth's mantle, the surrounding substrate becomes progressively hotter to varying degrees.

Geothermal [in Greek: "geo" = earth/"therme" = heat] energy is the most logical choice for establishing "green" "base-load" power. Estimates suggest that 50,000 times more energy exists in the upper 6 - 10 miles of the earth's crust in the form of heat [geothermal energy] than is contained in the entire global reserves of petroleum, coal and natural gas combined. In perspective, simple math suggests that this heat source could annually provide enough electricity for 350 trillion [yes, with a "T"] people. Clearly, this is not an inconsequential source of energy; it is more than sufficient to generate the quantities of electricity to power an electric-centric transportation system. Best of all, this "fuel" [heat] is free; no futures, no hedge funds, no cartels, no monopolies, no wild price spikes and swings, no unfriendly governments and no supply issues to contend with.

A sustainable and replenishable source of energy exists at depths of five miles beneath the earth's surface and it contains at least five times the energy needed to power this brave new electric world, on an annual basis. Going deeper still, there is much more potential energy available. As drilling technologies advance, access to these deeper and hotter zones can be attained. The thermal energy that will be derived from these deeper zones will be available to operate binary geothermal power systems that are capable of meeting the forecasted escalation in demand for electricity.

The potential energy in these deep zones is present all over the United States, at every location [at variable depths]. These deep zones are sufficiently hot to generate binary geothermal power. To access this tremendous source of energy, developers must drill to depths of five miles or more. It may seem like an insurmountable distance. However, technology presently exists in the petroleum well-drilling industry to do so on a vastly expanded scale. Today, companies are drilling oil wells to depths of five miles; a piece of cake. Imagine the windfall of economic activity for these drilling companies [Schlumberger, eat your heart out] if deep well binary geothermal power is ramped up to the level of a Manhattan Project or Apollo Program.

A deep well geothermal system is also referred to as an "enhanced geothermal system" [EGS] or "hot dry rock" geothermal system [HDR], as opposed to a "hydrothermal" system which is a more limited resource. A hydrothermal system exists where a naturally occurring superheated water reservoir is located relatively close to the earth's surface. These reservoirs are located mostly in the western United States and near subduction zones where tectonic plates meet and where volcanic and seismic activity is prevalent.

With a concerted deep drilling mind-set, exploration to discover thermal zones is not an issue. It is already known and accepted that if a well is drilled deep enough, hot zones will be located and those hot zones will maintain sufficient temperatures to operate a binary turbine and generate electricity. Technology to drill to the depths required to access heat on such a grand scale is the limiting factor. However, as stated above, technology presently exists to drill extremely deep; the ability to drill even deeper will become increasingly greater as the technology moves forward. More to the point, however. The cost to drill that deep on a universal scale will be enormous. But the cost incurred by doing nothing will be much greater. The unit cost to drilling deep wells should also decline as technology improves and more drilling is conducted. Not so with excessively expensive nuclear power plants. The potential environmental damage from this source of energy alone is too much to risk. And, the environmental damage associated with excessive coal use - if this is the preferred source of "base-load" energy - will be enormously costly. Here is where government intervention and financial assistance is crucial. The need to drill to these great depths, as well as the need to absorb the up-front capital expenses to do so, is a matter of national security - perhaps even economic and national survival. Only the government has the ability to undertake such a project. The government should take the lead on this vital matter of national security no less than it does when it annually spends north of 550 billion dollars on the military budget. Once the deep hot zones are located, the manufactured wells can be leased to private businesses for a fee to fully develop their electrical energy potential.

The most significant advantage that geothermal power has over other forms of "green" or sustainable/renewable energy is that it is considered to be a "base-load" source of electricity. That means electricity is produced "on demand", all of the time if need be. When electricity is needed, it can be generated. That is not the case for solar, wind, or tidal systems, all of which are subject to the vagaries of their source of power be it the sun, wind, or gravitational pull. Geothermal power is also reliable, possessing operating/generating capacities that reach a peak of 98 percent. Coal and nuclear power, in contrast, have variable operational capacities of between 75 - 95 percent. And, geothermal power is consistent; the heat needed to generate electricity is available day and night, in all weather conditions, 24/7, 365 days per year, with very little adverse impact on the environment. Consistent, available, scalable, reliable, renewable, clean, vast quantities, safe and secure. What is not to love?

This source of energy truly is a substantial resource even without considering energy potential of deep conventional geothermal resources ["DUGR"] - which are part of EGS. DUGR's are not addressed here because they involve reservoirs with extremely high temperatures and pressures. If included in the mix, DUGRs expand the potential available energy from an estimated 2,400 - 9,600 Exajoules [EJ; 1 joule = 6.2415 x 10(18) electron volts] to as much as 74,000 EJ, excluding super-critical volcanic geothermal systems located within national parks. That is a lot of potential energy.

DEEP WELL BINARY SYSTEM

What is a deep well "binary" geothermal system? Simply described, it is a system whereby a well is drilled deep into the earth's crust until a thermal ["hot"] zone is reached where the temperature of the surrounding rock exceeds that which is necessary to "boil" an inorganic liquid that has a lower boiling point than water. Although hotter temperatures are always preferable at all depths because greater potential efficiency can be attained by the geothermal system as the temperature increases, any well that can produce temperatures that exceed 225 degrees Fahrenheit contains sufficient thermal energy to generate binary geothermal electric power. Once the required temperature zones are reached, fracture zones are created in the rock substrate using various techniques which include instigating hydrostatic pressure [pumping pressurized water deep into the hot zone which causes expansion of the surrounding rock and creates multiple cracks which collectively form the subterranean water reservoir]. The fracture zone that is created is now permeable. Water is injected into this permeable fracture zone with an "injection" well, that water is heated by the hot rock which surrounds and is contained within the permeable reservoir, and the resulting hot water is then pumped to the surface via a "production" well. The hot water then enters into a heat exchanger which superheats an inorganic working fluid, thereby causing it to expand into a gas. The "steam" created by the gaseous expansion of the inorganic working fluid drives a turbine which in turn spins the generator that produces electricity.

More specifically, the binary system employs a second or "working" fluid in place of super heated water ["steam"] to drive the turbine and spin the generator. The working fluid typically consists of an inorganic liquid that is derived from hydrocarbons such as isobutane or isopentene, or a combination of different fluids of similar chemical composition [another reason to conserve petroleum - this use is better than burning it up in internal combustion engines]. These inorganic liquids are more "volatile" than water, they have different vapor pressures, and they possess far lower boiling points than water. The hot water obtained from the injection well is pumped to the surface through a combination of natural hydrostatic pressure caused by the weight of the earth as affected by gravity, and electric pumps which use residual or "parasitic" electric power that is obtained from the geothermal electric generation process. This hot water passes through a heat exchanger where heat is transferred from the hot water to the working fluid. The working fluid heats up, begins to expand and forms "steam". This inorganic steam turns a turbine in a process that is similar to the system that is based on water-steam. The turbine in kind turns a generator which produces the required electricity.

Two technologies commonly used today to produce electricity in a "binary" plant are the Rankine Cycle [named after its Scottish inventor, William Rankine] and more recently, the Kalina Cycle [named after its Russian inventor, Aleksandr Kalina].

There are many advantages to deep well binary geothermal energy: efficiency, availability of a large resource, environmental and economical. Let us explore a few.

Share Your Article!

Do you have an article? Share it!