The Residential Geothermal Enabler
SMACK provides residential geothermal energy with a set of shallow multilateral conduits that are deployed at 3 m below the surface using burrowing. SMACK is capable of harvesting geothermal energy for residential use without drilling vertically tens of meters into the ground. SMACK does not aim be the main or only source of energy for residential use; instead, SMACK aims to complement and reduce the use of and therefore the cost of electricity, gas, or other energy sources, and that is its key pragmatic reason that will increase exponentially the adoption and use of geothermal energy for residential use nation and worldwide. We must emphasize that SMACK can either collect geothermal energy to be used for residential heating during the winter or deposit underground the thermal energy collected from residencies during the summer. In its first embodiment, one will connect SMACK to Heat Pumps that are connected to the residence. the Section Fundamentals offers more details about the SMACK system engineering.
Why SMACK
Several companies are currently deploying Geothermal Residential Systems (GRS); however, potential users are not embracing it in massive quantities yet because its installation requires the use of heavy equipment that either drills vertically tens of meters below the surface or trenches almost the whole area surrounding the residence to which one aims to provide with geothermal energy. Besides disrupting the house’s surroundings for weeks during and after the installation, these methods need several days and cost thousands of dollars to get installed. Instead, SMACK will take about 1/10 the time the other methods take—only 2 hours to perform all the burrowing, and a total of 4 hours to install the whole GRS— and less than 1/10 the cost of current systems, while providing as much or even more energy one would obtain with other methods.
The first two 30 sec videos that follow communicate the significant disadvantages of GRS deployment using drilling and trenching. The third 30 sec video shows burrowing as used in a residential yard; the SMACK system, which uses burrowing, is not disruptive as the first two and takes only 1-2 hours to burrow and about 1/10 the cost of the first options; SMACK will make the deployment of GRS a viable solution that will allow the adoption of this renewable energy in the USA and worldwide.
Residential Geothermal installation with Drilling
This video shows how the GRS deployment using vertical drilling takes about five days while disrupting and damaging the house’s yard, which takes several weeks to recover. Just the drilling costs several thousand dollars, and the whole job takes many more
Residential Geothermal installation with trenching
This video shows how the GRS deployment using trenching takes several days while disrupting and damaging the house’s yard, which takes several weeks to recover. Just the trenching costs several thousand dollars, and the whole job costs many more.
SMACK: Shallow Multilateral Geothermal Complementary Energy System with Burrowing
Fundamentals
One of the key thermodynamics factors that influence how much and how efficiently the Heat Pumps can provide thermal energy to the residence during the winter or extract from the residence during the summer is the difference between the temperature inside the residence, T1, and the temperature outside the residence, T2; this difference is also call Delta Temperature (T1-T2). Fundamentally, during the winter, SMACK will increase the Delta Temperature by using the underground geothermal energy that provides a temperature that is higher than T2; this additional energy will be transferred by means of the Flx_Cd_Thfl into the Heat Pump, and from there into the residency. During the summer the process will be inverted; the underground temperature will be lower than the temperature outside the residence, and the thermal energy that one wants to extract from the residence to cool it will be transferred into the underground.
Matching horizontal burrowed length and vertical well performance
Most of the GRS use vertical drilled wells with average depth of 60 m (200 ft). In the next figure, Cambridge R&T communicates what would be the necessary horizontal length one would have to use, so the SMACK’s wells that are 3m deep, multilateral, and horizontally burrowed can provide the same thermal energy as a vertical drilled well that is 60 m deep. The thermal energy performance depends on geometric factors and the temperatures on the surface, at the 3 m deep horizontal well, and the 60 m deep vertical well; the models used to generate these graphs account for these variables. This particular graph assumes the surface temperature is 0 0C, the temperature at 3m is 44 0C , and shows the horizontal depth to match the thermal performance of a 60 m deep vertical well when the temperature at that depth is between 46 0C [115 F] and 50 0C [122F]. The graph shows in particular that the thermal performance of a 60 m deep vertical well is matched by horizontal lengths between 70 m and 90 m of burrowed horizontal wells that ran at 3m depth parallel to the surface. What makes this more relevant at the implementation level is that the 70-90 m can be burrowed simultaneously in 4 wells that have a length of only 20 m each with U turns.
Cost [$]: burrowing, trenching, and drilling
Cambridge R&T has estimated the cost of each of the two methods currently used to deploy Geothermal Residential Systems (GRS) in the USA. The following graph shows that drilling a 60 m deep vertical well can cost between $984 and $2364, this is just the drilling; the graph also shows that trenching can cost between $662 and $1589. However, burrowing the 40 m that will give teh equivalent thermal performance of the 60 m vertical well can cost between $15 and $404; this is if one rents the burrowing systems, if one buys them, the cost would be even lower. This shows that just burrowing can be less than 1/10 the cost of drilling vertical wells.
Time [hr] of burrowing, trenching, and drilling
The following graph compares the time it takes to drill the vertical well, trenching, and burrowing. The most revolutionary aspect of SMACK is that in about 30 minutes it can burrow the 40 m necessary to match the 60 m of vertical drilling well. This is about 1/12 the time it takes to just drill the vertical well; one must emphasize that in reality the deployment of GRS takes about 5 days minimum as the video https://youtu.be/wPJ56jN7Jtk shows.
The business case
Energy to heat a bedroom in the USA* 1 hr. 1.5 kWh, and 1-year 1820 kWh
Annual cost to heat ONE bedroom in the USA with electric energy 258.26 USD
Candidate COTS for GN&C and Steering
Guidance and Navigation
Steering (Control)
Steering: Basic concept with minor adjustements, after minute 2:08
How O&G steers while drilling
Steering: Most basic description of the fundamental concept.
Analysis
This file contains it:
Appendix
This video shows how they traverse underground to avoid having to break the road. Although they use rotary drilling instead of burrowing, their system is interesting and worth analyzing.
References
[1] Average electricity rates are based on October 2021 data from the U.S. Energy Information Administration (EIA). https://www.eia.gov/electricity/monthly/epm_table_grapher.php?t=epmt_5_6_a