Answering the Issues via Laboratory and Field Experiments

In November 1959 an eruption of the Kilauea Volcano half filled a prehistoric pit crater in the Hawaii Volcano National Park to a depth of about 400 feet. This lava lake was given the name little Kilauea or Kilauea Iki. Although not a true magma deposit the only significant difference between this lava pond and that of a true magma body is size, gas content, depth and pressure. Temperature and other material properties were close enough to real magma to provide a realistic laboratory. This fortunate gift of nature has since been destroyed through recent volcanic action. During its lifetime however, Kilauea Iki became a major research laboratory for the Sandia Laboratory and provided insight for the exploitation of magma as an energy resource.

There is evidence that magma resources do exist in the reachable upper 10 kilometers of the US Earth’s crust. Smith and Shaw (1975) list 47 volcano centers less that 10 km deep in the US where there is enough evidence for them to estimate the molten state.

“The evidence they used to select these centers include surface expressions (calderas, dated lava flows, fracture patterns, and uplifts) and geophysical anamolies (gravity, magnetic, seismic and other).”

Using Kilauea Iki as a laboratory for geophysical sensing studies it was possible to conclude that sound waves could characterize many of the dimensions of the magma lake, but electrical conductivity and seismic velocity of the melt needs to be measured to accurately interpret all the measurement values. Physical confirmation of magma characteristics are also needed to accurately characterize a magma body.

Some time during the 1980’s while expanding the number of steam wells for the Krafla geothermal power station In Iceland the State Electric Power Works unintentionally drilled directly into a magma dome. The drilling rig did a little dance and the agency soon pulled out, as they wanted steam not magma. Other than that mistake, no one has deliberately drilled into a magma body within the top 10 km of the surface of the Earth, however, holes have been drilled that deep, and holes also have been drilled into molten rock; Kilauea Iki is the prime example. A number of deep gas wells in Oklahoma and Texas have been drilled in sedimentary rock to 10 km depths. The Sandia drilling at Kilauea Iki includes several holes at 1050C and 33m through molten rock at magma temperatures about 1100C but no one had done both, 10 km deep and 1100 C in to magma.

The significant questions are: Can magma roof-rocks be drilled? Will drill holes through magma roof-rocks be stable and remain open long enough to allow the insertion of energy extraction equipment? The Sandia “Magma Energy Research Project Report (1982)” concluded the following on this subject:

“Boreholes in typical magma roof-rock at in situ conditions to 10-km depths can be kept open and stable by proper cooling and filling. Drill bit with cooling channels and well holes drilled into the melt zone can be kept open and stable as long as desired by cooling with a stream of water from the surface. If redrilling is needed due to cooling it is easily accomplished.”[7]

Molten magma bodies offer a source of high-quality, pollution-free, thermal energy. Based upon the Sandia National Laboratory research with actual magma and the conclusions of C.J.M. Northrup’s research, that storable fuels can be produced via the available chemistry in magma. The energy extraction technologies that seem most worthy of further research are, hydrogen, natural gas and carbon monoxide. Steam production for electric power generation is the simplest and most obvious method for extracting energy from magma. However, storable fuels are even more valuable, the production of which takes full advantage of the 900C–1300C temperatures of magma. Steam production does not need these temperatures.

Figure 4. Schematic drawing of 1981 Lava Lake Open Heat-Exchanger Experiment by Sandia Laboratories. This design was used successfully in the Lava Lake (Kilauea Iki) during the test period.

The Figure 4. diagram is of the Sandia, Kilauea Iki (Lava Lake) energy extraction device. It was designed to produce steam only by sending pressurized water to the bottom of the cased hole and extracting the steam through open holes higher in the pipe casing – as shown. What is not seen is a large-surfaced heat exchanger created by injecting water that formed a large fractured crust of permeable solidified rock (which once was magma) adjacent to the borehole. In this heat exchanger concept water is circulated through the hot-fractured rock zone (which is the heat exchanger) where the water is converted to steam and drawn off to the surface.

Sandia Laboratory described the experiment as follows:

“A hole was drilled to a depth of 68 meters (into Kilauea Iki) extending approximately 10 meters into the melt zone. Casing was set from the surface to the full depth. We then reduced the cooling water flow down the casing allowing the melt to flow and seal around the end of the casing. The hole was then extended to a depth of 74 meters by drilling through the end casing an additional 6 meters. The final geometry of the experiment was a sealed (cased) conduit from the surface of the lava lake to an open (uncased) 6-m experimental section in the molten zone. Pressurized water was injected through the down-comer into the open experimental section under both steady and intermittent conditions for a week’s duration. The intermittent cooling of the experimental section by the pressurized water, caused solidification and thermal fracturing of the molten region surrounding the borehole. Stress analysis of this configuration showed that both radial and horizontal fractures should occur, resulting in a highly permeable, rubbled bed of fractured rock. A finite thickness of near molten, plastic rock surrounds this cooler rubbled zone acted as a seal to prevent fluid loss. All of the water (95% to100%) injected into the rubbled cavity in the molten zone during the experiment was recovered during the steam production phase, demonstrating that a closed, sealed cavity had indeed been produced in the melt. “

“Energy-extraction rates as high as 950kW/m2 were measured during transient operations. During steady water-injection operations, an energy-extraction rate of 180kW/m2 was measured.” Note that nuclear power plants operate at energy-extraction rates at less that 180kW/m2.

“During the first 48 hours of the experiment’s operation, energy-extraction measurements showed that heat flux based on original borehole surface area increased with time. The transient behavior was opposite from that expected for conductive heat transfer in a solid, indicating that the rubblized region surrounding the borehole grew with time, increasing the heat-transfer area for energy extraction. This effective area has been calculated and shown as a function of time in Figure 5. The factor of 10 increase in effective heat transfer area is significant and was reached after only two days of operation.”[8]

Figure 5. 1981 Growth of heat exchanger area ratio of the Lava Lake Open Heat-exchanger Experiment. This data suggests that the area might grow even more as the days progressed which would be a positive.

Although this energy extraction was from a lava lake, and not at the expected depth of a workable magma body, there seem to be no reasons to think that a similar technology would not successfully extract quantities of turbine steam limited only by the number of boreholes one wished to bring on line. But steam is only one of the possible energy extractions.

Sandia Laboratories did not use the open heat exchanger device at Kilauea Iki to test the fuels production concepts proposed by Northrup et al (1978). What was use was a Magma Simulation Facility operated at the Sandia site in Albuquerque, NM in which biomass and water were converted using the interaction with the iron oxide in magma to produce natural gas, carbon monoxide, hydrogen and steam. And alternatively, without the biomass to produce just hydrogen. In effect the biomass is hydrogenated to produce a higher quality multi-use fuel (Natural Gas).

“There are ample (natural) options for generation of gaseous fuels from water-biomass conversion with magma-thermal energy. A wide range of magma types and pluton styles occur within the upper 10 km of the crust to provide suitable sources for thermal energy for water-biomass conversion throughout magma life-times of 1500 to 600,000 years. Fuels can be generated within a magma body, within the hot subsolidus margins of a magma body, or within a surface reaction vessel heated by thermal energy derived form a magma body. “
“The composition, concentration, and energy content of the fuel gases generated from a particular water-biomass mixture does not change appreciably with the type, age, depth, or temperature of the magma body. For any upper crustal magma body, the concentration of generated fuel and its energy content is almost entirely a function of the proportion of biomass in the starting mixture. CH4 (natural gas) is the main gas that can be generated in important quantities by magma-thermal energy under most circumstances. The possibilities for significant H2 generation are restricted either to heat exchangers operating at high temperatures (800C) in the tops of very shallow basaltic magma bodies or the surface reaction vessels operating at temperatures in excess of 600 C. Under either of these conditions, H2 production would be achieved at the cost of reduction in the rates of both fuel generation and heat extraction through associated steam production.”

“The rate at which gaseous fuels can be generated from water-biomass mixtures is strongly dependent on the type of magma involved. Fuel generation rates for basaltic magma are 5 to 6 times those for andesitic magmas and 5 to 6 times those for rhyolitic magmas for similar biomass concentration levels and generation temperatures.”

“The energy content of the biomass-derived fuel is considerably greater by a factor of 6 to 12 than that consumed in the generation and refinement process for all conditions examined.” In simple terms this means that the energy content of the produced fuel was 6 to 12 times that of the feed stock sent into the process.”[9]

Figure 6. Concentrations of principal species in mole percent for mixtures of water and cellulose (C6, H10, 05) at 600 C and 100.0 Mpa. The concentrations are shown as a function of the weight percent (C6, H10, 05) in the mixture. For a Magma Power Plant this means as the weight of cellulose is increased in the feed stock the production of natural gas will go up in proportion to the Carbon dioxide and carbon monoxide while hydrogen production will stay the same percentage. The carbon dioxide is useless, however the other products are all useful fuels.

During FY84, the Geothermal Technology Division of DOE initiated the Magma Energy Extraction Program to investigate engineering feasibility. The primary goal of the program was to develop and demonstrate the technology needed to produce power from magma resources so that industry could evaluate economic viability.[10]

“In the United States, the major potential of magma energy is in the form of silicic melts that have accumulated in the crust at relatively shallow depths.”[11]

The engineering project was directed at utilization of this potential resource. The planned technology developments included energy extraction, material, drilling, and source definition so that wells could be drilled into large magma bodies and energy extracted for electric power production. The focus was on a deep exploration well in the Long Valley Caldera of California. The well was targeted for the near magmatic regime of the caldera and designed for a depth of 20,000 feet.

Long Valley Objectives

The primary objective was to confirm the existence of magma at drillable depths beneath the surface. This well was scheduled to test the very foundation of the magma energy concept—that huge quantities of molten magma reside in the crust at relatively shallow depth. Because of its size and recent activity, the Long Valley Caldera was considered one of the best locations in the U.S. to test this hypothesis.

An additional objective was the testing and calibration of surface geophysical methods for magma location and definition. Numerous surveys had been completed in the Long Valley with conflicting results. The well results would provide hard evidence of structure beneath the resurgent dome and wellborn measurements of density, electrical conductivity and seismic velocity would greatly improve the accuracy of geophysical data analysis from the surface.

The magma program was organized to address engineering feasibility by investigating four primary areas: 1: geophysics, 2) drilling, 3) energy extraction, and 4) geochemistry.

Due to the early cancellation of the project only the geophysics objectives were undertaken although thorough planning in each area including advanced engineering designs were accomplished.

By all measures if was a high risk project, but apparently worth the risk because of the high pay off resulting from the first tap into generations of pollution free energy. However, the project moved slowly and during the third phase the project ran into a funding policy shift away from high-risk high pay-off projects while at the same time the borehole readings seemed to indicate a missed judgement as to were the magma body was really located or it’s depth. Long Valley failed because the temperature readings that were expected to climb during the last 3000 feet (from 7,000 to 10,000 ft.) stayed the same (see Figure 9.) while at the same time the Department of Energy shifted funding policy.

Figure 7. “Generalized map of the Long valley Calderia, California, showing the resurgent dome, Long Valley Exploration Well (LVEW), and significant post-caldera-collapse volcanic areas.”[12]

Figure 8. “Cross-section from southwest-to-northeast across the caldera complex. The working hypothesis for the presence of recurring volcanic activity associated with the caldera is that mafic injections occur periodically resulting in convective overturn of the rhyolitic magma chamber causing near surface intrusions and volcanic activity. The intrusions then drive periodic hydrothermal fluxes possibly originating in the basement rocks and then traveling laterally through the caldera volcanic fill.”[13]

Figure 9. “Temperature profile for Long Valley Exploratory Well (LVEW) from data collected by Ron Jacobson, Sandia National Laboratories. Note the relatively normal geothermal gradient to approximately 6500 feet. Temperature then becomes essentially isothermal to the bottom of the well.”[14]

This section covers a rough conceptual design of a Magma Power Plant designed by the Sandia Laboratory in 1980 using the results of several laboratory experiments and the engineering parameters for a conventional steam turbine power plant. The data for this plant was then compared to a conventional boiling water nuclear plant at a 1000 MWe scale.

The dotted line in Figure 10. is the present value of nuclear power plant construction as of 1980 and line #1 which ranges over a heat extraction rate of 1 to 100 kWt/m2 is the balance of plant and Well cost at $375 million. Line #2 is similar to line #1 but with balance of plant cost at $210 million. The interpretation of this data leads one to say that the costs at the time (1980) would lead one to believe that a magma power plant would be less expensive than a nuclear plant at the higher heat extraction rates levels. Note that it has been the heat extraction rate that has caused private companies to balk at the risk of a magma plant—they want more data.

Figure 10. Economic Analysis of a Magma—Electric Power Plant 1000 MW e compared to a conventional nuclear power plant of the same parameters, by Sandia National Laboratories. (Note the log-log scales).