Fixing the Energy Problem

Solution for Power Generation

Thermoelectric/ Nuclear

As water prices increase, we except power plants to switch to methods that minimize water withdrawal and consumption. These include switching to dry cooling, considering cogeneration and combined-cycle technologies or using treated wastewater in cooling systems if the latter improvements are not feasible.


Assuming our plans and projections are met, corn production should decrease as it becomes less economically favorable to produce in the Southwest. As the biomass market is expected to grow, it would be favorable to substitute displaced corn production with production of native types of biomass. Cultivating perennials grasses, such as switchgrass, will be more water efficient due to their adaptability to the climate of the High Plains.

Natural Gas-Fired Combined Cycle

Combined-cycle power plants are to power plants as hybrid electric automobiles are to totally gas fueled automobiles. A combined-cycle gas turbine power plant is a plant in which one or more gas turbine generators equipped with heat recovery steam generators. The steam produced from these generators is used to power another turbine which adds the total output of the system. This way, only part of the energy produced is produced from water, and therefore, less water will be needed when cooling. According to an EPRI report about water and stability, the relative consumption of freshwater due to thermoelectric energy protection is actually slowly shrinking due to the increase in thermoelectric power plants with combined-cycle systems, however this trend may or may continue over a long period of time (EPRI, 2002).

The general idea of a combined-cycle power plant is basic. A generic "1 x 1" combined-cycle plant consists simply of the gas turbine generator, the heat recovery steam generator, and the steam turbine generator. First, fuel is combusted releasing energy used to turn the gas turbine. Then, excess heat is recovered using the heat recovery steam generator. In the heat recovery steam generator, the heat is used in order to boil water, thus producing steam to power another turbine, the stream turbine generator. A normal power generator, in contrast, uses the all of the energy produced by converting water into steam and then turning a steam powered turbine with that steam. Therefore, less water would be required to cool a combined-cycle power plant than a regular power plant (cooling water is used to cool the ambient air heated due to the steam production). According to the Northwest Power Planning Council, a combined-cycle power plant employing technology common for large combined-cycle power plants, can produce about 270 megawatts of capacity at reference standard conditions"(Northwest Power Planning Council, 2002). For more efficient systems, multiple (usually two) gas turbine generators can be used with respective heat recovery steam generators. The output from these generators would fuel a single steam turbine proportional to the amount of gas turbine generators. This setup (a "2 x 1" setup since two gas turbines are used, generally an "n x 1" setup), according the Northwest Power Planning Council, can produce around 540 megawatts of capacity at standard conditions (Northwest Power Planning Council, 2002).

As an added bonus, combined-cycle power plants are very versatile in terms of fuel source. The only limitation on the type of fuel that the power plant must use is the gas turbine. Gas turbines can run on both liquid and gaseous fuels, which include natural gas. Natural gas would be the more favorable of fuels due to it's "historically low and relatively stable prices"(Northwest Power Planning Council, 2002) In addition, it provides relatively low carbon dioxide emissions due to methane being a large constituent of natural gas (Northwest Power Planning Council, 2002).

As far as output is concerned, the standard combined-cycle power plant can produce around 540 megawatts, as mentioned before. In addition, augmentations can be added which can increase this number to around 600 megawatts (Williams, 2008). For example, duct firing, a method in which natural gas is burned directly in the steam heat generator, can increase peak capacity by 20 - 50 megawatts for a 1 x 1 combined-cycle power plant (Williams, 2008). According to The Future of Coal, a study conducted by MIT, the average electrical output is around 500 megawatts (MIT, 2008). Therefore, the combined cycle power plants would be more energy efficient, in terms of water usage.

Although the 2 x l combined cycle power plant used less cooling water in order to produce energy, the 1/3 of the energy production process which relies on steam turbine generators still needs a cooling process. The amount of water needed is minimal. In the EPRI report on water and sustainability, the amount of water withdrawn to cool the steam turbine component of a 2 x 1 combined-cycle power plant is approximately 230 gallons per MWh while 180 gallons per MWh are consumed (EPRI, 2002). This is roughly half of the 500-600 gallons per MWh needed for a conventional thermoelectric power plant as seen on the chart below (EPRI 2002).

Table 1: EPRI report data on average water withdrawal and consumption, based on cooling design

  Plant and Cooling System Type Water Withdrawal (gal/MWh) Typical Water Consumption (gal/MWh)
Fossil/biomass/waste-fueled steam once through cooling 20,000 to 50,000 ~300
Fossil/biomass/waste-fueld steam pond cooling 300 to 600 300-480
Fossil/biomass/waste-fueled steam cooling towers 500 to 600 ~480
Nuclear steam, once through cooling 25,000 to 60,000 ~400
Nuclear steam, pond cooling 500 to 1100 400-720
Natural gas/oil combined-cycle once through cooling 7500 to 20,000 ~100
Natural gas/oil combined-cycle cooling towers ~230 ~180
Natural gas/oil combined-cycle ~0 ~0
Coal/petroleum residuum fueled combined-cycle, cooling towers ~380 ~200

Therefore, the most efficient thermoelectric energy producing system (water wise) would employ dry cooling technology as well as combined-cycle technology.

Revamping Current Power Production Plants


To make use of hydropower's potential, while protecting the implied ecosystems, we propose to first demolish dams that are obsolete or do not produce enough power to merit expensive repairs. The demolished dams will be primarily small dams that are either too old to repair in an economically efficient manner or that are causing too much ecological damage. The dams that remain should be repaired accordingly as to assure minimal environmental impact. We also propose utilizing small-scale hydropower, which provides clean energy without the major environmental side effects of larger scale projects.

As old dams are either destroyed or repaired, small-scale hydropower plants will likely play a more significant role in providing energy to citizens. They have already been successfully implemented in Europe, the United Kingdom, Australia and some Third World Countries. Small-scale hydro consists of a system of small turbines installed in bodies of water with relatively low head and flow. These systems are designed to provide energy for specific consumers, or small communities. Unlike large-scale hydro, these systems do not depend on a reservoir. Instead, water is passed through the turbines, whose rotational energy is converted to electric energy through a generator or alternator. The water is promptly allowed to return to its natural flow (Micro-Hydropower Systems, 2004).

Micro-hydroelectric systems are more compact and cost effective than many types of energy production. The cost of these systems can range from $1500 to $2500 per kilowatt of installed capacity, depending on the location and given capacity of the system. There are two types of systems, which result in two different ranges of total costs, when taking into account initial costs (setting up the turbines) and annual costs (maintenance and repairs). The first of these systems is a hydropower facility with a battery for storage. These are generally the least expensive micro-hydropower systems, and can be used for lighting or domestic purposes. The second type of micro-hydropower machinery is the AC-direct system, which is most similar to the power generation equipment used by utilities. These transfer energy directly rather than storing it first. AC-direct systems are appropriate for both on the grid and off the grid systems. These systems are small and intended for domestic use, but could be expanded to generate more power for a greater number of users.

Various companies have begun using micro-hydropower as an alternative source of energy. The company Bourne Energy is only one of many that has designed a micro-hydro unit. The companies states their unit, called RiverStar, repels fish with a delicate pressure wave that emerges for the front of the turbines, which they do not expect to significantly harm wildlife. Each unit is said to generate up to 50kW in a four knot current. The micro hydro must be installed in arrays, or in groups of 20 units, which are connected up to 10 feet under the surface of the river by steel plates (2008). Another example is Electrovent, a Canadian company that has installed turbines in rivers to supply energy near hunting and fishing camps. Yet another is the project by Morehead Valley Inc., which generates 120 kW to the BC Hydro Grid in British Columbia, Canada, and has been in place since 1994 (Cunningham and Woofenden, 2008). Based on these examples, it would be feasible to place micro-hydroelectric power generation systems in small rivers, for example, in Colorado River tributaries.