Geothermal's Path to Relevance: Cheap Drilling26 Oct 2021 19:26
For balance [and to make cuddo smile?]
https://austinvernon.site/blog/drillingplan.html
Geothermal's Advantages
The energy industry is going through a long-term deflationary period. Unconventional oil and gas, solar, wind, and batteries have all experienced rapidly falling costs. Every technology comes with tradeoffs. Solar and wind are not dispatchable, batteries have limited duration, and shale hydrocarbons require constant investment and a sophisticated supply chain.
Modern Geothermal provides:
High Capacity Factor (24/7 production)
Zero Fuel Costs
High Power Density (Plants use little land)
Provides Electricity, Heat, or Combined Heat and Power
Can be Sited Almost Anywhere (Reducing transmission costs)
Enough Energy Available to Power the World
Geothermal is a candidate to replace aging nuclear and hydropower plants, given that renewing permits for both types of generators will probably become difficult. It is also great to pair with industrial users that have steady 24/7 electricity demand.
Why don't we have geothermal everywhere? It's too expensive. Geothermal market share growth depends on substantial cost reductions.
Modern Geothermal's Requirements
All that energy is beneath our feet, but it is diffuse and low quality, making cost-effective extraction challenging.
Deep Wells
The Earth's temperature increases as you drill deeper.
Heat engines that convert heat to electricity are more efficient at higher temperatures.
Deep wells produce higher volume and quality of heat, reducing the cost and increasing the effectiveness of generating equipment.
For various reasons, few startups are attempting to drill deep, simple, and cost-effective wells. Their long-term cost goals are above current wholesale electricity prices. The few pursuing a cheaper path have a long technology roadmap or are underfunded. I wrote more about this topic in a blog post.
Widespread Availability
Most existing geothermal power plants drill into hot water (hydrothermal) reservoirs. These resources are rare, making geothermal a niche source of energy. Any attempt to expand the scope of geothermal means drilling without readily available hydrothermal reservoirs and where the thermal gradient is less steep. Not everywhere has volcanoes. Enhanced geothermal systems (EGS), hybrid systems, and closed-loop systems are proposed solutions for hot, dry rock.
Closed-loop systems are like a radiator, only gaining heat through conduction from the rock. Hybrid systems have a closed-loop working fluid but use fracturing techniques to induce convection in reservoir fluid. EGS connects multiple wells through fracturing and circulates fluid between them, using the reservoir rock as extra heat transfer area and volume.
The following proposal is applicable for closed-loop, hybrid systems, and possibly deep EGS with some modifications. More detail on these ideas is available in the same blog post.
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