Monday, February 4, 2008

materials input

This Summery formats very poorly on blogger.  However the information is very important in assessing the future cost of materials input for renewable energy sources.  It is usually assumed that EROI life cycle input is the critical issue, but I am concerned about the actual cost of input materials.   The cost of input materials will be a major factor in total energy cost. 

Summary of Sergio Pacca and Darpa Horvath 2002 Greenhouse Gas Emissions from Building and Operating Electric Power Plants in the Upper Colorado River Basin

There is a large area of research devoted to figuring out how much material, energy, and cost is required to build various types of power plants. To estimate the overall greenhouse gas (GHG) emissions over the life cycle of a plant, Pacca and Horvath used Life Cycle Assessment (LCA), a method that calculates materials extraction, manufacturing and production, operations, and the disposal of the materials at the end of the life of the power plant.

As you can imagine, this isn't easy. There are two main LCA models -- Pacca and Horvath chose the EIOLCA approach, which uses a large commodity matrix that tries to identify the entire chain of suppliers of the raw materials, and then this matrix is multiplied by another one containing emissions and energy use per dollar.

Because dollars fluctuate in value, a better method would be to calculate the energy used at every step of the chain, but still, these dollar amounts give a rough idea of the embedded energy.

The study compares the Glen Canyon dam with four other types of power plants, all figures are scaled to each plant producing 5.55 TWh of energy per year.

This kind of study could help decide which direction a future energy Manhattan project should. This study rules out a Photovoltaic power plant, which is not possible now -- it requires 4118 MW of power, but the total world production of PV modules up to 1997 was only 125 MW, less than 3% of what's required for just this one plant. The PV plant also displaces an enormous ecosystem, about 20 square miles.

This study does not cover nuclear power plants. Another study states "nuclear fission energy requires small inputs of natural resources compared to most other fossil and non-fossil energy technologies. When we consider net electricity generation (e.g., net electricity after subtracting consumption by internal plant loads and by uranium enrichment plants), the life-cycle resource inputs for non-fossil power sources are dominated by construction materials, most notably steel and concrete. The construction of existing 1970-vintage U.S. nuclear power plants required 40 metric tons (MT) of steel and 190 cubic meters (m3) of concrete per average megawatt of electricity (MW(e)) generating capacity. For comparison, a typical wind energy system operating with 6.5 meters-per-second average wind speed requires construction inputs of 460 MT of steel and 870 m3 of concrete per average MW(e). Coal uses 98 MT of steel and 160 m3 of concrete per average MW(e); & natural-gas combined cycle plants use 3.3 MT steel and 27 m3 concrete" (1).

Below are two tables summarizing the data.
GWE: Global Warming Effect is the Greenhouse Gas (GHG) emissions in MegaTons of CO2 equivalent, which is calculated by adding CO2 + CH4 +N2O together
MT = MegaTon = 1,000,000 Metric tons. 1 MT = 2,204.62262 pounds

Here's just wind since it didn't format properly below:
Construction-- Farm
Input---- Total MT
--------------- ---------
copper................ 1,569
electricity MWh.....1,691,678
excavation m3

(1) Peterson, P. F. Will the United States Need a Second Geologic Repository? The Bridge 2003, 33 (3), 26-32.

Hydro PV Wind Coal Nat Gas
Construction Plant Plant Farm Plant Plant
Input Total MT Total MT Total MT Total MT TOTAL MT
--------------1- --------- --------- -------- -------- --------
aluminum 67 177,788 6,275 624 230
cement 2,222,356
concrete 9.906.809 1,266,172 178,320 71,270
copper 90 480,029 1,569
electricity MWh 7,556,010 1,691,678
excavation m3 4,711,405
glass 1,066,731 4,930
oil 448
plastics 20,169
sand 9,412
steel 32,183 4,600,276 289,987 62,200 51,130

Operational Inputs
coal combustion 2,336,000
coal extraction 2,336,000
transportation by railroad 2,336,000
natural gas combustion 1,560,300,000 m3
natural gas transportation 1,560,300,000 m3
natural gas extraction 1,560,300,000 m3

TABLE 2: COST, GWE (Global Warming Effect), and Area required

Total Cost Area
(1992 $) GWE required
----------- ------- --------------
Coal Power Plant 149,772,446 90,000,000 n/a
Wind Farm 206,881,416 800,000 489,580,000 m2
Natural Gas Plant 374,033,481 50,000,000 n/a
Hydroelectric Dam 503,240,216 500,000 651,141,400 m2
Photovoltaic Plant 3,578,457,990 10,000,000 51,386,400 m2

NOTE: the cost in 1992 dollars doesn't include labor, installation, or maintenance costs.

Photovoltaic Plant 100-W panels of dimensions 1.316 x 0.66 m with array units of 3 x 10 panels, each having its own concrete foundation, for a surface area of 3.9 x 6.6 m, sited at 30° latitude, at a 30-deg tilt (approximately 1.2 m of additional width is needed to account for shading by the array due to the sun's angle). There is 0.9 m between each of these array units for personnel access. Each adjacent unit covers a land area of 37.44 m2 and has a capacity rating of 3 kW. Some 1,372,500 of these 3 kW units are required.
Wind Farm location: Southern Utah, at 7,000 feet. average windspeed 6.5 m/s turbine: 600 kW in 4480 turbines

Hydropower: As the U.S. Bureau of Reclamation has suggested, "upgrading hydroelectric generator and turbine units at existing power plants is one of the most immediate, cost-effective, and environmentally acceptable means for developing additional electrical power".

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