Geothermal Energy Hayley Dutka James Gallagher Jonathan Koslop.

Geothermal Energy

Hayley DutkaJames GallagherJonathan Koslop

Overview

• Geothermal Electricity• Geothermal Power Plants• Facts• Legal Movement• Advantages vs Disadvantages• Production Enhancement• Coproduction

Geothermal Electricty • Geothermal energy is currently used in

24 countries, with the United States producing the most

• World production has 10,715 MW of geothermal power capacity online and produced 67,246 GW h (gigawatts/hour) in 2010. This is a 20% increase from 2005

• The International Geothermal Association (IGA) predicts this number will grow to 18,500 MW capacity by 2015

Dry Steam Power Plants

• Dry steam plants are the simpliest and oldest• Use geothermal steam of 150°C or greater to turn turbines

Flash Steam Power Plants

• Flash steam plants pull deep, high pressure hot water into lower-pressure tanks and use the resulting flashed steam to drive turbines.

• Require fluid temperatures of at least 180°C, usually more.• Most common type of plant in operation today

Binary Cycle Power Plants• Recently developed• Can accept fluid temeratures as low as 57°C• The moderately hot geothermal water is passed by a secondary fluid with a much

lower boiling point than water. This causes the secondary fluid to flash vaporize, which then drives the turbines.

Hot Dry Rock Geothermal Heating• In order to generate electricity you need the heat from in the earth which must be

carried to the surface by fluid circulation.• In some situations fluids are unavailable so it is possible to inject water or liquefied

carbon dioxide down a borehole to extract the heat

Facts about Geothermal Energy• There is an enormous amount of thermal energy deep within the earth, that is

replenished at a very high rate. This amount is conservatively estimated to be higher than all the fossil fuels and uranium combined

• Geothermal electricity only gives off an 1/8th (12.5%) of the emissions that coal does. Also other types of power plants are usually equipped with emission-control systems to reduce exhaust. Geothermal plants could theoretically inject their gas emissions back into the earth, as a form of carbon capture and storage

• Geothermal plants use 404 square meters per GWh versus 3,632 and 1,335 square meters for coal facilities and wind farms respectively

• Only uses 20 liters of freshwater per MWh verses over 1000 liters per MWh for nuclear, coal, or oil.

• Geothermal energy is not susceptible to price fluctuation like crude oil• The US government has offered tax credits for individuals who use the technology

in their homes. So basically you could have one of the highest efficiency heating and cooling systems in your home for a discount.

• Geothermal energy is always available, 365 days a year.

Laws, Advantages, and Disadvantages

Most Recent Legal Movement

• Energy Independence and Security Act of 2007, which includes the “Advanced Geothermal Research and Development Act of 2007” is the most recent direction and authorization provided by the House and Senate.

• “In General- The Secretary shall support programs of research, development, demonstration, and commercial application to expand the use of geothermal energy production from hydrothermal systems, including the programs described in subsection (b).”

Advantages of Geothermal Energy• 1. Environmentally Friendly – There are some

polluting aspects associated with geothermal energy, but not near the amount of polluting aspects associated with conventional fuel sources. (coal, fossil fuels). The power stations do not take up much room, so there is not much impact on the environment

• 2. Renewable - reservoirs come from natural resources and are naturally replenished. Geothermal energy is a resource that can sustain its own consumption rate – Unlike conventional energy sources such as coal and fossil fuels. Geothermal energy generally involves low running costs since it saves 80% costs over fossil fuels and no fuel is used to generate the power

Advantages Continued…• 3. Massive Potential - Worldwide energy consumption –

about 15 terawatts (TW) – is not anywhere near the amount of energy stored in earth. However, most geothermal reservoirs are not profitable and we can only utilize a small portion of the total potential. Realistic estimates for the potential of geothermal power plants vary between 0.035 to 2 TW.

• 4. Stable - Geothermal energy is a reliable source of energy. We can predict the power output of a geothermal power plant with remarkable accuracy. This is not the case with solar and wind (where weather plays a huge part in power production). Geothermal power plants are therefore excellent for meeting the base load energy demand.

Advantages Continued…• 5. Great for Heating and Cooling - We need water temperatures of

more than 150°C (about 300°F) or greater in order to effectively turn turbines and generate electricity with geothermal energy. The earth is generally more resistant to seasonal temperature changes than air. Consequently, the ground only a couple of meters below the surface can act as a heat sink/source with a geothermal heat pump.

• 6. Prevalence and Economy - There has been a tremendous growth in the number of homeowners that utilize geothermal heating/cooling in the last couple of years. Since ancient times, people having been using this source of energy for taking bath, heating homes, preparing food and today this is also used for direct heating of homes and offices. Geothermal energy on the other hand has created many jobs for the local people.

Disadvantages of Geothermal Energy

• 1. Environmental Issues - There is an abundance of greenhouse gases below the surface of the earth, some of which mitigates towards the surface and into the atmosphere. These emissions tend to be higher near geothermal power plants. Geothermal power plants are associated with sulfur dioxide and silica emissions, and the reservoirs can contain traces of toxic heavy metals including mercury, arsenic and boron.

• 2. Surface Instability (Earthquakes) - Construction of geothermal power plants can affect the stability of land. In fact, geothermal power plants have lead to subsidence (motion of the earth’s surface) in both Germany and New Zealand. Earthquakes can be triggered due to hydraulic fracturing, which is an intrinsic part of developing enhanced geothermal system (EGS) power plants.

• https://www.google.com/search?q=newcastle+australia+earthquake&source=lnms&tbm=isch&sa=X&ei=DKyLUoyZNszh4APbxIGwDg&sqi=2&ved=0CAcQ_AUoAQ&biw=1920&bih=1084#q=newcastle+australia+earthquake+1989&tbm=isch

Disadvantages Continued…• 3. Expensive - Commercial geothermal power projects are expensive. The

exploration and drilling of new reservoirs come with a steep price tag (typically half the costs). Total costs usually end up somewhere between $2 – 7 million for a geothermal power plant with a capacity of 1 megawatt (MW). The upfront costs of geothermal heating and cooling systems are also steep. On the other hand, these systems are likely to save you money years down the line, and should therefore be regarded as long-term investments. Ground source heat pumps typically costs $3,000 – $10,000 and have a payback time of 10 – 20 years.

• 4. Location Specific - The big problem is that there are not many places where you can build a geothermal power station. You need hot rocks of a suitable type, at a depth where we can drill down to them. The type of rock above is also important, it must be of a type that we can easily drill through. Good geothermal reservoirs are hard to come by. Some countries have been blessed with great resources – Iceland and Philippines meets nearly one third of their electricity demand with geothermal energy. If geothermal energy is transported long distances by the means of hot water (not electricity), significant energy losses has to be taken into account.

Disadvantages Continued…• 5. Sustainability Issues- Rainwater seeps through the

earth’s surface and into the geothermal reservoirs over thousands of years. Studies show that the reservoirs can be depleted if the fluid is removed faster than replaced. Efforts can be made to inject fluid back into the geothermal reservoir after the thermal energy has been utilized (the turbine has generated electricity). Geothermal power is sustainable if reservoirs are properly managed. This is not an issue for residential geothermal heating and cooling, where geothermal energy is being used differently than in geothermal power plants.

Can production be enhanced in those areas in which it is already developed?

YES!

EGS

• An approach to capturing the heat in dry areas under the earths surface.

EGS

Co-Production

• Oil and Gas companies.

• Allows for geothermal to be produced in areas with little activity.

Co-Production

Shale

• Since shale and the drilling of it are relatively new this is good for geothermal.

Shale

Questions/Comments?

• http://www.youtube.com/watch?v=O6r_3AgI49Y&feature=player_embedded

Works Cited

• http://energyinformative.org/geothermal-energy-pros-and-cons/

• http://geo-energy.org/KeyGeothermalLaws.aspx

• http://www.geothermal-energy.org/