Geothermal Energy


Geothermal Energy: Renewable Energy and the Environment
by William Glassley

Main Points:
  • Drill a production well and an injection well- and use the heat to power a binary power generating system.
  • Two parameters
    • Permeability- ability for fluid to flow through the subsurface
    • Temperature- need temperature to run the turbines (higher the gradient, the shallower you need to drill to get access to energy)
    • Iceland is in the lower right hand part of the graph and New York is in the upper left hand side. 
  • The largest geothermal power plant in the world is at the Geysers in California which is north of Santa Rosa and west of Sacramento (no it isn't in Iceland).
  • Enhanced geothermal systems- we frack the reservoir in the subsurface and we can circulate the fluid through the subsurface. 
  • West- yellowstone and caldera. Through Utah, Nevada, and Oregon you have the "Sun Belt" where there is plenty of high grade hydrothermal. 
  • East- the Appalachian basin, Ithaca, and West Virginia has some gradients that are high, but not that much geothermal going on over there. Does this make sense?
    • Space Heating and Water Heating is about 14% of energy use/year. This comes from natural gas or oil combustion or propane. 
  • The US uses 100 quads (or exojoules) per year. There are about 10,000 quads of high grade geothermal in the US. We have 2.5 Gigawatts of electricity produced today from geothermal energy. IF we lower our standards and use this for heating our homes, we can dramatically increase the amount of energy we can use from geothermal. The is called "direct use":
    • heating of pools and spas
    • greenhouses and aquaculture
    • space and district heating
    • snow melting
    • agricultural dying
  • In the 1800's after the Civil War in Boise Idaho the first district geothermal heating plant was introduced in the United States, this area is known as Kelly's Hot Springs.
  • China has become the world's largest distributor of geothermal heat. 
  • The costs of geothermal resources is not a linear function of depth, but the completed well cost is a two parameter exponential function of depth. This model is called "WellCost Lite".
Challenges:
  • Need accessible high temperature rock and a high gradient 
  • Connected well system
  • Flow rate- water needs to flow and last long enough (sustainability)
  • Means of utilizing the energy (direct steam flashing to organic Rankine cycle to co-gen)
  • Exergy (kJ/kg) vs. temperature- the vertical scale (exergy) determines the maximum the amount of power or useful work that you can get out of a heat resource. The higher temperature and pressure reaches the supercritical region where you get the most amount of exergy (availability)- this is where Icelandic Deep Drilling Project is trying to tackle. For most resources in pure liquid water, we are capped at 200 kj/kg. 

Jefferson Tester Lecture:
  • Numbers
    • US Population: 315 million people
    • Land  Use Density: 
      • 33 person/ sq.km
    • Primary Energy Demand: 
      • 100 quads/yr
    • Per Capita Energy/yr: 60 BOE/yr
    • Number of Cars/ Trucks:
      •  250 million
    • Electric Generating Capacity: 1 TWe
  • History for baseload geothermal
    • Began at Larderello, Italy in 1904 
    • World, geothermal is 11,000MW
    • US geothermal electric capacity is 3400 MWe
    • Additional capacity with direct use/geothermal heat pump: 60,000 MW
    • 20% of electricity in Iceland comes from geothermal energy (Blue Lagoon)
  • EGS
    • Projects that contributed to EGS
      • Cooper Basin (Australia)
      • Fenton Hill (Los Alamos)
      • Hijori and Ogachi (Japan)
      • Rosemanowes (UK) in the Cornish Granites
      • Soultz (EU)
    • How Important is the drilling technology? 
    • Need to understand the connectivity of reservoirs
      • Project Results: directional drilling (5+km), diagnostics and models for size, thermal hydraulic behavior, making large regions of stimulated rock
    • Economics
      • quality/ accessibility (10 to 100 degrees)
      • productivity/lifetime (20-80 kg/s with 5-20 yr life)
      • end use- direct use vs. electricity generation
      • cost of drilling a well
      • Use GEOPHYRES models for LCOE and LCOH
      • For different reservoir qualities you have different LCOE and LCOH:
        • Average US Price Electricity: 10.8 c/kWh
        • Average US Price Heat: 14.8 $/MBTU
        • Gradient is 25 Celsius/km: 37.5 c/kWh
        • Gradient is 25 Celsius/km: 25.9 $/MBTU
        • 80 degrees celsius/km gradient means that LCOE and LCOH is close to average US prices!
  • Direct Geothermal Energy- making use of the ground at its normal temperature. In Melbourne the temperature is about 18 degrees (average temp of air) about 2 meters below the ground. 
    • A: Ground Loops- running water through the ground
    • B: Ground source heat pump
    • C: Building that has demand for heating and cooling
    • Method: pass water through pipes in the ground (12 degrees that picks up heat from 18 degree outside and goes up to 14 degrees). 
    • Coefficient of Performance: for every dollar spent on electricity to run the heat pump, you are getting 4x that energy for heating and cooling. You are getting this energy for the quarter of the price. You have reduced your carbon footprint by factor of 4.
    • Summer- dump hot air from house (24-25 degrees to 18 degree ground in Melbourne) and this comes up at 22 degrees. Bore hole diameter is about 120 mm. 
  • Reinforcing cage for large bore pile. If you make vertical and horizontal holes.
  • Korea has hectare of green houses 
  • Heat pump- a machine that moves heat from one point to another. Water goes through a heat exchanger, the refrigerant will boil, it will go into a condenser (70-80 degree increase), air from house becomes hot, causing the refrigerant to liquefy. The common fridge is a heat pump. 
  • Advantages:
    • Sustainable and renewable energy source
    • Available 24/7
    • Provides major reduction in carbon footprint
    • well established technology: 3 million installations in Europe/ North America
    • Can be used anywhere
  • Disadvantages:
    • Largely overlooked by public
    • Few people know, have heard, or understand it
    • Costs are a little high at present, but will be increasingly competitive as industry matures, competition develops, carbon taxes bite, and subsidies are introduced.
  • What temperature is the ground soil six feet under?
    • 15 degrees Celsius or 60 degrees Fahrenheit
  • How much energy?
    • 40% of the energy we use in a building can be sourced from geothermal
  • How does the drilling work?
    • Drill a small diameter hole (size of mason jar), push a plastic pipe (HDPE from NG) down into the ground 200-300 feet. Heat pump, U-bend, the drill rig, the fusion machine that makes the joint stronger than the pipe itself. 
    • Advanced Ground Source Heat Pump- powered by a natural gas combined cycle power plant (that takes in 6 kWh and outputs 2.7 kWh). The Ground source heat pump will get 7.3 kWh from the ground and we get 10 kWh. 

Have a few questions about Geothermal? Checkout the Department of Energy Geothermal FAQ page!

Expert in geothermal energy and former author of the MIT report on geothermal energy, Professor Jefferson Tester of Cornell University gives a talk on the future of EGS!

Listen to this podcast by The Energy Gang in 2013 on the state of geothermal, around minute 21:00 Jigar Shah alludes to the fact that geothermal companies should leverage the drilling tax incentives that oil companies use for techniques like horizontal drilling!

Listen to a Ted Talk by Ian Johnston (Melbourne) on the topic of geothermal energy!

Read the EERE's seminal report "The Future of Geothermal Energy: Impact of Enhanced Geothermal Systems" or watch this Ted Talk by one of the co-authors Professor Anderson of West Virginia University!

Comments

Post a Comment

Popular posts from this blog

Consider a Spherical Cow

Image
Consider a Spherical Cow: A Course in Environmental Problem Solving by John Harte Main Points: What is the "spherical cow" joke ? The phrase comes from a joke about theoreticians I first heard as a graduate student. Milk production at a dairy farm was low so the farmer wrote to the local university, asking help from academia. A multidisciplinary team of professors was assembled, headed by a theoretical physicist, and two weeks of intensive on-site investigation took place. The scholars then returned to the university, notebooks crammed with data, where the task of writing the report was left to the team leader. Shortly thereafter the farmer received the write-up and opened it to read on the first line: "Consider a spherical cow..." The Approach : The spherical cow approach to problem solving involves the stripping away of unnecessary detail, so that only the essentials remain. Of course, approaching the complex world from the spherical cow perspective
Read more

Should We Risk It?

Image
Should We Risk It? by Daniel M. Kammen & David M. Hassenzahl Main Points: " I began by trying to quantify technical risks, thinking that if they were 'put into perspective' through comparison with familiar risks we could better judge their social acceptability. I am ashamed now of my naivety, although I have the excuse that this was more than 20 years ago, while some people are still doing it today. "- Harry Otway (1992) Background: Daniel Kammen teaches a course at UC Berkeley called "Environmental Classics" where they rotate through key papers/books like Amory Lovins' paper "A Road Not Taken", the Wedges paper. They read the original items- the critiques that came at the time and the critiques that come after. Only Silent Spring  becomes a fixture in the course year after year.  Take a look at Kammen's lab RAEL and BREG  for sustainability tools and what tools we need to alter the dialogue around clean energy or sus
Read more

Read one Book a Week

I once participated in an energy club in grad school. The club was composed mainly of grad students from several departments and disciplines - engineering, business, and law. Our mission was to foster a diverse energy community and enable interdisciplinary collaboration, knowledge exchange, and professional development. Over the course of two years, the club grew in size from 20 to over 100 students, creating its first alumni mentoring program, taking tours of several energy companies, hosting its first energy case competition, installing the largest solar panel array in the local neighborhood, building a vertical axis wind turbine, and collaborating with several organizations around the nation. I loved it. Mainly because of all the great friends who made my time in the club truly memorable. Much of what we were trying to do was to understand the energy environment from those who worked, taught, and preached about it daily. While talks and small group dinners got us interested, I fe
Read more