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By Jim Bell



The Potential

Using Solar Generated Electricity as a Primary Fuel

Conversion Efficiencies: Comparing Complete Fuel Cycles

Using Solar Generated Electricity As a Primary Energy Resource

Collector Distribution

The Advantages Of A Diversified System

Renewable Energy: Putting An Integrated Package Together

Energy Storage

If It's So Easy, Why Hasn't It Happened?

True-Cost-Pricing And Solar Energy










From an economic perspective, investing in efficiency improvements provides a better return than investing in even the most cost-effective energy supply system. But renewable energy is the next best investment if the social and environmental costs associated with conventional energy sources are included in the economic analysis.

Investing in efficiency and in renewable energy resources is also the best way to eliminate our dependence on non-renewable energy resources altogether. The more efficient we become, the easier and less costly it will be to replace non-renewable energy sources with renewables. From a purely security perspective, this strategy would eliminate dependency on imported energy supplies and, if executed properly, make energy supply and distribution systems much less vulnerable to natural phenomena or intentional human acts.






The Potential








Given the studies cited in the last chapter, it seems reasonable to assume that the present U.S. economy could run quite nicely on one-fifth or less of the energy it currently consumes, if all the cost-effective efficiency measures available were in place today. Indeed, with true-cost-pricing, energy consumption could be cost effectively reduced even further.

In addition to saving energy, becoming more energy efficient also makes it easier to replace non-renewable energy sources with various forms of solar energy. Although combining energy efficiency with solar energy makes the most sense from an eco-nomic security perspective, even without efficiency, we have plenty of solar energy.

On a global scale, "if solar cells with only 10-percent conversion efficiency were placed over one quarter of the Sahara, they could supply 3.5 x 10 (to the 14 power) kilowatt-hours or 40,000 gigawatt-years of energy each year -- the projected world energy demand in 2050" (without efficiency improvements). (330) Forty thousand gigawatt-years is just under 1195 quads or 40 terawatts (TW) of energy. This is 8 times as much energy as would be required globally each year in 2050, if state-of-the-art efficiency measures (best available in 1982) were in place. (331)

Dennis Hayes, the founder of Earth Day, comes up with a similar solar availability scenario. According to Hayes, "if we convert the insolation (sunlight) striking 1/2 percent of the land area (on our planet) at 20 percent efficiency, we can harness 26 TW" or around three times what we inefficiently consume today globally or would need in the year 2050 with efficiency. (332)

Sunlight falling on the U.S. landmass (yearly) carries about 500 times the 85 quads of energy the United States (currently) consumes in a year." (333) Obviously, not all of this energy can be captured. But, according to the book Cool Energy, published by the Union of Concerned Scientists, "if just 1 percent of U.S. land were adapted to collecting solar energy at 25 percent conversion efficiency, over 100 EJ (96 quads) would be made available each year." (334)

Although possible with today's technology, producing 96 quads of energy per year on 1 percent of U.S. land area is probably a bit optimistic. One of the best collectors yet developed and field tested, that would be suitable for such a task, is the McDonnell Douglas Parabolic Dish/ Stirling Engine Solar Electric Generating System. During clear sunny periods, this system achieves overall efficiencies of 23 percent with efficiencies as high as 30 percent during midday periods. In other words, 23 percent of the sunlight intercepted by a McDonnell Douglas collector, on a clear day, is converted into electricity.

If the overall efficiency of the McDonnell System could be boosted to 25 percent, the collector surface needed to produce 96 quads of electricity would be approximately .5 percent of the land area of the United States. This equals half the 1 percent U.S. land area projected in the Union of Concerned Scientist's book Cool Energy.

But, in addition to collector surfaces, solar collectors also need to have space between them. This is especially true for dual axis tracking collectors like the McDonnell Douglas system. Given today's technology, two axis tracking is necessary to achieve an overall efficiency of 25 percent. Since the collector surface needed to produce 96 quads of electrical energy each year is .5 percent of U.S. land area, the Ground Cover Ratio (GCR) of the Cool Energy 1 percent projection, would be 50 percent. The percentage of land at a collector site that is actually covered by collectors is called the Ground Cover Ratio or GCR. Unfortunately, a GCR of 50 percent means that about 14 percent of the sunlight that could have been collected and converted into electricity each year, would be lost. This is because collectors packed in so tightly would partially shade each other in the morning and afternoon when the sun is low in the sky.

For perspective, one percent of U.S. land area equals one-tenth the land area currently devoted to agriculture in the United States. (335)

Ultimately, the most eco-nomically secure energy system for a region or country would include as many forms of renewable energy as are available. Additionally, this system would be configured to be as decentralized as is practical. This approach would make it difficult for natural phenomena or intentional human acts to interrupt large parts of a region's or country's energy supply.

But, for purpose of getting a better idea about how much renewable energy is out there, let us assume that if the efficiency measures discussed in Chapter VII were in place today, national energy consumption would only drop to 25 percent of its current level. In other words, instead of using 85 quads of energy per year as we do now, we would only be using 21 quads. Since the sun does not shine or the wind blow 24 hours a day, we will add another 9 quads extra capacity for storage for a total of 30 quad energy supply for each year. (336) (It will be shown later that this is probably much more storage than is actually needed. See index - Energy storage, for more details.) Further, let's assume that we will supply all of this energy in the form of electricity made from renewable resources.

If we set the goal of producing 30 quads of electrical energy each year, how much land would be required, given the following assumptions:

  1. 1. That the collectors we use will have and overall conversion efficiency of sunlight into electricity of 23 percent, (the McDonnell Douglas system has already achieved this level of efficiency.)
  2. 2. A ground cover ratio of 33 percent.

    A GCR of 33 percent as opposed to 50 percent would make building a system more cost effective by reducing the number of collectors required. A ground cover ratio of 33 percent instead of 50 percent would also reduce the problem of collectors shading each other. With more distance between them, collectors would shade each other less in the morning and afternoon than would be the case if more of them were packed into the same space. On the positive side, this would increase the total output from each collector system -- less shading equals more power. On the negative side, increasing the space between collectors, would reduce the amount of total electricity that could be produced per unit of land. In addition to being affected by numerous factors like available sunlight, collector efficiency, and shading, the optimal GCR for an area would also need to reflect the cost of land in comparison to the cost of collectors.
  3. 3. A daily average of 7 kwhrs of heat energy delivered (reflected) to receivers per square meter of collector per year.

    This is approximately the amount of sunlight available in a number of locations in Southeast California, Arizona, New Mexico, Southern Nevada, and Southern Colorado. (337)

    Note: As collectors follow the sun, the solar energy they intercept is reflected to a receiver where the concentrated solar light is transformed into heat which drives a heat engine that powers an electric generator.
  4. 4. That the systems would be 95 percent reliable.

    In other words, 19 out of every 20 solar electric devices would be fully operational, whenever there was sufficient solar insolation to produce power at a site. Once in operation, system reliability could exceed 95 percent considering that:
    • System components like heat engines, generators, tracking motors, tracking sensors, and mirrors can be modular, ie. designed so that any component needing repair could be replaced in a few minutes; and
    • More extensive repairs could be done at night.

Given the assumptions just discussed, it would require approximately 6,000 square miles of collector surface to produce 30 quads of electricity annually. With a ground coverage ratio of 33 percent, the land occupied by these collectors would be 18,000 square miles. If located in one place 18,000 square miles would cover an area of land 140 miles by 140 miles.

Eighteen thousand square miles is approximately .5 percent of the land area (excluding areas covered by water) of the United States. (338)

Eighteen thousand square miles is roughly equivalent, in area, to 60 percent of the land currently occupied by military bases located on U.S. territory. (339) It is also equal in area to about 5 percent of the land area currently used for agriculture in the United States. (340)

In the past, large scale solar plants have been criticized as being more land intensive than conventional energy sources. Research now indicates that this is not the case. Studies conducted by the Office of Conservation and Renewable Resources at the U.S. Department of Energy in 1989 have shown that coal and uranium have comparable land requirements, but at different stages in the electricity production cycle. Solar and wind power require the use of land at the generating site whereas coal and nuclear energy "consume land at fuel-extraction sites." (341)

Further, mining is only one of many steps in the extraction, processing, transportation, use, and disposal cycle through which coal or any other non-renewable resource must pass to derive usable energy from it -- steps which have multiple impacts which consume land and hurt the plants, animals, and people that inhabit it.

Though it requires less land than for coal and uranium, drilling for oil and natural gas also has large impacts. Land is impacted during the process of exploring for oil and gas and when they are extracted after discovery. Additionally, land and water are contaminated by oil spills. Oil contaminates oil fields and oil spills, particularly in coastal areas, can devastate large fishery and wild life habitat areas. After oil and natural gas are located, more land is impacted by the construction and maintenance of pipe lines and burning all fossil fuels causes acid rain.

Another factor is that extracting uranium, or any other non-renewable energy resource, consumes new land on an on-going basis. Once a source of non-renewable energy is consumed, more land has to be impacted to continue the supply. With solar energy this is not the case. Once a solar or wind system is in place it will continue to produce the same amount of energy forever, if maintained. And it will never use another square meter of land unless its capacity is expanded. Even biomass (plants grown as energy crops) can be grown in the same location indefinitely, if the nutrient rich ash from burning them is returned to the growing site. And solar energy in all its forms is not an energy resource we have to worry about using up.

When all the costs are considered, it is clear that use of conventional energy resources impacts far more land, in numerous interdependent ways, than would be impacted if the same amount of energy was produced using renewable energy resources.

This is not to say that solar technologies are completely benign. In addition to land requirements, they also require metal and other materials to be extracted and processed for their construction. They also need to be maintained. But, once in place, their impact is minimal. This will be especially true if the devices (solar collectors, windmills, etc.) are installed and maintained in ways that are sensitive to the habitat needs of installation areas and designed to be easily recycled when they wear out - which would be standard procedure with true-cost-pricing.






Using Solar Generated Electricity as a Primary Fuel








When electricity is generated by burning fossil fuels or through nuclear fission, about 1/3 or less of the energy embodied in the original fuel (the primary energy source) is converted into electricity. This thermodynamic (heat) loss is an unavoidable aspect of changing a primary form of energy into electricity. If the energy consumed by the whole fuel cycle (locating an energy source, extracting and processing it, getting it to a power plant, and disposing of its combustion wastes) is included, the amount of electricity produced is an even smaller fraction of the total energy involved.

Because of these inefficiencies, electricity is usually reserved for tasks which only it can perform, like powering electric lights and electric motors. It is not normally used for tasks like heating water, unless a primary energy source like natural gas is unavailable. Once it is delivered to a water heater, however, close to 100 percent of the electricity used is converted into hot water. But when the conversion losses discussed earlier are included we see that the actual efficiency is no better than 100 percent of 33 percent (even without discounting fuel cycle losses) of the original primary energy source used to create the electricity. Whereas, if natural gas is used to heat water directly, around 70 percent of the primary gas energy will be converted into hot water.

However, if solar energy is used to make electricity, it makes sense to approach the concept of efficiency from a different perspective. Even though using solar energy to generate electricity is subject to thermodynamic losses similar to those experienced when a non-renewable resource is used for the same purpose, these losses can be largely discounted.

Unlike converting non-renewable energy resources into electricity, converting solar energy into electricity is more related to the land or roof area required to produce the desired amount of electricity, not the energy lost in the conversion process. The availability of non-renewable energy resources is finite while the supply of solar fuel is infinite. Solar conversion efficiencies are important, not because of the waste of fuel, but because higher efficiencies can reduce the amount of land and collector hardware needed to produce the desired amount of power. And as was previously discussed, solar energy already uses less land to produce a given amount of electricity, than do non-renewable energy resource. If photovoltaic cells are installed on roof tops, it could be argued that other than procuring the raw materials to make them, photovoltaics use no land at all.






Conversion Efficiencies: Comparing Complete Fuel Cycles








Actually, the 23 percent conversion efficiency achieved by the McDonnell Douglas system in converting solar energy into electricity probably exceeds the conversion efficiencies of some non-renewable energy resources, if the energy consumed by their complete fuel cycles is included. Delivering a form of non-renewable energy to the power plant where it can be used to generate power requires the expenditure of energy on a number of levels. Considerable energy is used in finding a resource, mining or drilling for it, processing it, and transporting it, before it ever gets to a power plant. It also requires energy to control, store, and dispose radioactive waste and coal ash sludge after the electricity is produced. Added to this is the energy consumed in mitigating the numerous environmental and social costs that are caused by using of non-renewable energy resources.

If these energy expenditures are included in the efficiency equation, generating electricity using devices like the McDonnell Douglas system may prove to be more efficient over all than producing electricity from either fossil fuels or nuclear power. Indeed, using solar generated electricity produced at an overall efficiency of 23 percent may even be more efficient for direct heating than using non-renewables like natural gas and oil if a true-cost analysis of all the energy used up in their fuel cycles are included. Even without true-cost accounting, one source projects that "'it will be pointless to continue exploring for oil and gas'" after 2005 in the United States because "after that more energy would be used to look for these fuels than the oil and gas we found would contain." (342)

Note: With the exception of solar energy in its various forms, the real efficiency of any energy source is the amount of energy that actually ends up providing a service divided by the amount of energy consumed during that energy source's fuel cycle. This includes the energy required to mitigate any social and environmental damage that the fuel cycle precipitated. Solar energy does not fall under this definition because, over time, the amount of solar energy available on our planet is infinite, and solar energy has no fuel cycle liabilities with the possible exception of biomass--growing plants as energy crops.

Unlike non-renewable energy resources, solar fueled systems do not even have fuel cycles. The possible exception to this is biomass (energy crops) which have to be grown, harvested, and delivered to a power plant or a processing facility. For systems that use a form of solar energy directly, the energy is delivered directly to the collector field or wind farm ready for use and its use produces no wastes. Constructing and maintaining collector fields or wind farms does require energy for mining and processing metal and mineral ores and to assemble and maintain collectors. But, as preceding chapters have shown, the energy consumed in creating a collector field and the environmental damage sustained during the process of creating it is decidedly less damaging than those that occur when any non-renewable energy resource is used.






Using Solar Generated Electricity As a Primary Energy Resource








It is therefore practical to use solar generated electricity as a primary energy source except where direct solar heating can do the job. For example, it makes more sense to heat water with a solar water heater than to use solar energy to generate electricity for this purpose. However, using solar generated electricity as the backup energy source for a solar water heating system is probably more efficient than using natural gas, when all the fuel cycle and environmental costs associated with using natural gas are included.

Another argument for using solar generated electricity as a primary energy source is that electricity is more efficient at its point of use than other energy sources. Once it is produced, electricity is more efficient at getting a task accomplished than any other energy source except direct solar for heating things like water and space. When water is heated with natural gas, 20 to 30 percent of the energy released by burning the gas is lost out the exhaust stack. If electricity is used, the water is heated by a heating rod inside the tank from the inside out. Therefore, almost 100 percent of the energy applied is converted to hot water. (343)

If direct solar collectors for heating water or making steam are backed up with solar generated electricity instead of natural gas, 20 to 30 percent less energy is required to perform the same backup function. In other words, if 100 units of gas energy are needed to provide backup energy for a solar water heating system per year, only 70 to 80 units of electrical energy would be required to do the same work. Instead of needing a collector area large enough to produce 100 units of electrical energy to replace 100 units of gas energy, the 100 units of gas energy can be replaced by 70 to 80 units of electrical energy. Because less energy is needed, the amount of collector area needed to get the job done can be reduced accordingly.

This is even more true for transportation than for heating water if vehicles are powered by solar generated electricity instead of by internal combustion engines. If 100 units of energy in the form of a fuel like gasoline are consumed in a vehicle powered by an internal combustion engine, only about 20 units of the energy in that fuel will be converted into vehicular motion. (344) Because of internal combustion engine inefficiencies, 80 percent of the energy in the gasoline is lost as waste heat. If we include the energy used up in finding, extracting, delivering, and processing the oil to make the gasoline, the overall efficiency of the vehicle will be considerably less than 20 percent.

If the same vehicle is fueled by 100 units of energy in the form of electricity, 65 units of energy in the electricity will be converted into vehicular motion. Well designed electric motors are 90 to 95 percent efficient at converting electricity into work. (345)

Even if we include energy losses associated with battery charging and the small amount of energy that is used up when batteries are charged and discharged, we still end up with efficiencies of around 65 percent. (346) In other words, if we start with 100 units of energy in the form of electricity and use it to charge the batteries of an electric vehicle, around 65 units of the electricity we started with will be converted into motion. This efficiency advantage means that powering the same number of vehicles over the same distance with electricity would require less than one-third the energy needed to move them the same distance with fossil fuels. (347) And again, if we start our energy calculations from when the oil to make the gasoline was still in the ground, the advantage of powering vehicles with solar generated electricity becomes even more attractive.

If the fleet average for all U.S. automobiles is 100 miles per 120,000 Btu's of gasoline (approximately 1 gallon), it would only require 40,000 Btu's of electrical energy to move the car the same distance. In other words, we do not need to produce as much solar generated electricity to do the same work as if we used gasoline or natural gas to do it.

This efficiency advantage has a positive implication related to how many solar collectors or windmills we would actually need to meet our energy needs. If 5 quads of gasoline energy are required to power the U.S. auto fleet, it would only require 1.6 quads of electricity to power the same number of electric cars the same distance. In terms of collector area, this efficiency advantage means that the 18,000 square mile collector area projected in our thirty quad scenario could be reduced by approximately 2,000 square miles if all cars were powered by solar generated electricity. (348)

By substituting electric powered auto transport wherever practical with electric powered light rail, even more energy can be saved. Electric powered light rail is powered directly and does not suffer from efficiency losses related to charging and using batteries. The more that electric powered cars are replaced by electric powered mass transit, the less collector area needed to provide enough energy for the same service.






Collector Distribution








Although it would be possible to locate a concentrating collector system in one place, it would actually be more efficient as well as more secure from a national defense or natural disaster perspective if it was distributed along the sun belt from Florida to the deserts of California. This would reduce storage requirements because the energy being produced would better match peak energy use across the country.

Peak energy use occurs during the day when most people work and when both work-places and homes are being heated in the winter or air conditioned in the summer. This period of peak use continues to a lesser extent into the early evening when people are cooking, taking showers, and watching television. Many stores and other commercial enterprises also remain active in the early evening.

If collectors are distributed across the southern states, their output in the southeast would closely match the energy needs of the east coast in the morning and throughout the day. As the earth rotated, collectors further west would come on line to supply energy directly to the eastern and central states into the evening and supply the far western states during the daylight hours.

Additional generating capacity would go into storage to supply the west coast with energy in the evening and for cloudy periods. With this type of distribution, it is less likely that more than a small portion of the overall system would be under clouds at any one time. Although the yearly average amount of sunlight available in the eastern portion of the sunbelt is less than that in the western portion, the difference would be made up by minimizing the amount of energy needed for storage. (349)






The Advantages Of A Diversified System








As has been shown, it would be relatively straightforward to fill all our energy needs using solar concentrating systems located in the southern part of the United States--especially if efficient energy use was aggressively pursued. Nevertheless, it would be even more efficient, require less land and energy storage capacity, and be better for national security if a more diversely based renewable energy system was developed.

Ideally, this system would be a mix of the various forms of renewable solar energy available in a particular region or country.

Wind Energy

Of the various forms of solar energy available, wind energy can be a big contributor to this energy mix. Even if we only consider land areas with suitable average wind speeds (12 mph and higher) that are not being used for non-compatible purposes, the potential energy production from wind power in the U.S is between one and four trillion kwhrs of electricity per year or 3.4 to 13.6 quads. (350)

According to the U.S. Department of Energy, thirty-seven states have sufficient wind power resources "to support development of utility scale power plants, and there are ample winds for small, residential-size wind turbines in all 50 states." (351)

Since 1981 the performance of wind power systems has improved steadily. (352) In response to these improvements, "Wind generated electricity has risen from 6,000 kWh in 1981 to almost 2.8 billion kWh in 1991." (353)


Biomass could also be a substantial contributor to the U.S. energy mix. Unlike direct solar or wind, which are intermittent, biomass stores energy that can be used to supply energy when wind and solar are inadequate.

Forestry and agricultural wastes alone can supply 3 to 5 quads of primary energy per year. These sources alone come close to meeting U.S. fuel needs for transportation if transportation efficiencies approached what is currently technologically feasible. (354)

If provisions to grow energy crops are included, biomass could supply 9.6 to 23 quads of primary energy per year. (355) John I. Zerbe, the manager of the Energy Research, Development, and Application Program for the U.S. Forest Service's Forest Products Laboratory (maintained in cooperation with the University of Wisconsin) holds a similar view. He believes that a strong Federal Department of Energy "commitment (to biomass) could lead to the production of 6.2 quads by (1995) -- and 10 quads by 2000." (356)

A study by the Stanford Research Institute called the Effective Utilization of Solar Energy To Produce Clean Fuel reported yields of eucalyptus as high as 312 cubic meters per hectare "on rich land in Brazil". (357) At .7 tons per cubic meter (air dried), this represents a yield of 88 tons per acre per year. (358) Eucalyptus wood, air-dried to 6 to 12 percent moisture content, contains 25% more energy pound for pound than lignite coal. Air dried eucalyptus contains 8,500 btu's per pound verses 6,330 btu's per pound for lignite coal. (359) Additionally, if growing areas are treated properly the yield will continue indefinitely whereas coal can only be extracted from a particular area once.

One way biomass could be utilized would be to link freeway landscaping and urban forestry. Irrigation and fertilizer for such operations could be supplied by recycled sewage water and composted sewage sludge. Once this system was established, trees would be harvested and replanted as part of an ongoing cycle. Once harvested, wood would be converted into liquid fuels to power vehicles and clean burning charcoal which could be used like coal to produce electricity.
Using current technologies, around 50 percent of the energy contained in a biomass material is lost in the process of converting it into a liquid fuel. But if solar generated electricity supplied the necessary conversion energy, all the energy embodied in the biomass could be converted into liquid fuels and charcoal. Additionally, the amount of electrical energy required to do the conversion work would be less than if biomass was used to supply it. This is because electricity could provide the needed heat internally, which would avoid the 30 percent stack loss that providing the conversion energy with biomass would incur. Using solar generated electricity for biomass conversion would also maximize the amount of biomass that could be stored as a back-up energy source. Taking this approach, biomass becomes a storage battery that can be burned like coal in power plants to supply electricity during periods when direct solar, wind, or hydro power was producing less electricity than required.

In some parts of the country natural brush lands could be harvested as energy crops. Chaparral, which has a higher energy content than eucalyptus, periodically burns off on average every thirty five years but reaches a semi-climax or dormant stage at about 20 years. (360) By harvesting every 20 years, the semi-dormant stage of the chaparral cycle can be shortened. Shortening the dormant period would increase the amount of plant material produced in an area over a given time. This is because vigorous growth will be taking place during what otherwise would have been a dormant period of almost no growth. Reducing the period of dormancy could also improve conditions for animal life. Like fires, harvesting would remove low production, hard to penetrate (by people and wildlife) growth which would be replaced by accessible productive growth.

To keep the harvest cycle viable, nutrients would have to be applied to the harvest area to replace the nutrients embodied in the woody materials removed from the site. When harvesting virgin sites, imported nutrients would be applied as an area is being harvested. During subsequent harvests, nutrient balances would be maintained by returning the ash residues from previous harvests to the growing area.

To protect wildlife, harvesting would be suspended during animal breeding seasons. In addition to the moral issues of protecting wildlife, a viable wildlife population is vital to healthy watershed maintenance. (See index for more entries.)

The economics of using chaparral as an energy crop looks promising. One study conducted at San Diego State University in California projected that chaparral, harvested and processed for burning, could be delivered for $28 per dry ton to a steam-electricity generating facility. (361) At that price, the energy value of a ton of chaparral would make it equivalent to purchasing oil at ten dollars a barrel. (362)

Chaparral economics is even more attractive when fire control benefits and reduced insurance costs are included in the economic package. Tens and, in bad years, even hundreds of millions of dollars worth of property are lost when chaparral dominated brush areas erupt into wildfires. If an attentive harvest regimen was followed, much of this loss could be avoided. Including some of these savings in the economics of harvesting chaparral makes this energy option all the more attractive.


Though its contribution is not likely to increase substantially (most of the good dam sites have already been used), hydroelectric power already contributes 3.1 quads of electricity. (363) There appears to be a considerable amount of small scale hydropower (small dams and small turbines) potential around our planet. But installing such systems will not be practical unless the watersheds that deliver water to them are protected.






Renewable Energy: Putting An Integrated Package Together








Considering only the conservative estimates for the amount of energy available from wind, biomass, and hydropower, the total is over 16.1 quads. (364) This would mean that 13.9 quads of energy would still have to be powered by solar thermal systems to meet our 30 quad energy budget. The area of land required, using the previously discussed assumptions, to produce 13.9 quads of electrical energy would be approximately 8,340 square miles or an area 90 miles by 90 miles if located in one place.

If we assume that the potential for wind and biomass is half-way between the low and high estimates in each category, the total energy available is almost 27.9 quads. (365) In this scenario, the need for the solar thermal production of electricity is almost eliminated. If we deduct the 3.3 quad savings in transportation energy gained through electric powered cars, we would have a 1.2 quad surplus even without using solar thermal systems. (See index - Solar electricity as a primary energy source.)

Indeed if we include the 30 quads of electrical energy from concentrating solar collectors, we get a total of 57.9 quads or almost twice what we actually would need in our 30 quad scenario. (366)

Photovoltaic (Solar) Cells

Additionally, there are still other renewable energy options available. For example, if the typical house in the U.S. was up-graded to the efficiency level, adjusted for climate, of the super-insulated houses in Canada and equipped with efficient lighting, appliances, and a solar water heater, it could be kept comfortable and perform all of its functions on 5 kwhrs of electricity per day or less. (367) A one hundred square foot photovoltaic panel could supply this amount of electricity quite easily in areas of the country that are reasonably sunny. Even if the need was 10 kwhrs per day, it could be produced by a roof-top solar cell panel 10 feet wide and 20 feet long. (368)

At least half of all the buildings in the U.S. are in climate zones that would allow them to be partially or completely energized by installing solar cells on their rooftops. Roof mounted solar cells on buildings and parking structures could be used to charge-up batteries in electric cars -- directly during daylight hours while they are parked at work. In the evening, vehicles could extract energy from batteries or a flywheel that had been charged up by solar cells mounted on the roof of one's home during the sunny part of the day. (See index for more details.)

At their current cost, without true-cost-pricing, it is difficult to justify the use of photovoltaic (PV) cells for some applications. Nevertheless, in 1988, approximately $150 million worth of solar cells were sold. (369) This represents a generating capacity of over 30,000 kilowatts, enough power "to supply 10,000 homes." (370) Although still more expensive than other solar electric options, the cost of solar cells continues to fall. Currently, photovoltaic cells can be purchased for $4.50 per peak watt of production. (371) At this price PV cells are cost effective for many applications such as for homes and equipment located in places where grid connection would be more costly.

The Rocky Mountain Institute estimates "that PVs and efficiency can often beat a 400-meter (power) line extension." (372) A case has been made that even where power grids are close at hand, it may be cost effective to equip new homes with a photovoltaic system for producing electricity and a bank of batteries for storage. This is called a stand-alone system. Typically, utilities charge $7 to $15 per foot to extend a local utility grid. Even if the grid only has to be extended 200 feet, the cost of the extension would be $1,400 to $3,000. If this money is applied to the purchase of photovoltaic cells and storage batteries instead, it can sometimes tip the economics in favor of solar cells. Especially if the house in question is equipped with the most efficient appliances and lighting system.

New breakthroughs in photovoltaic technologies promise to bring the price of solar cells down even further. A partnership between Southern California Edison and Texas Instruments has resulted in the development of a new less costly solar cell. This cell, which is expected to sell at around $2 per peak watt, is scheduled to be introduced into the marketplace late in 1994. (373) At this price, solar cells would be competitive in almost any application with most other energy production systems even without true-cost-pricing.

Wave And Tidal Power

Other potential renewable energy sources include wave and tidal power. Wave power can be used to drive hydraulic pumps which pressurize hydraulic fluid to drive generators. Where tidal differences are extreme, tidal flows can be used to turn generators to produce electricity. Tidal systems should be used cautiously since they can cause serious ecological problems to marine ecosystems.

Aquatic Biomass

Aquatic plants like kelp can be grown as energy crops along the continental shelves or in deep ocean areas. Dr. Howard Wilcox, the principal researcher for the Deep Ocean Kelp Project, envisions floating deep ocean kelp rafts that could supply all of the world's energy needs in the foreseeable future.

In Wilcox's system, free drifting juvenile kelp plants would attach themselves to a polypropylene grid suspended at a depth of 100 feet from buoys in the deep ocean. Since surface waters in the deep ocean have very few nutrients, these would be supplied by pumping nutrient rich water from a depth of a 1,000 feet to the surface. This takes very little energy because the pumping action involves lifting water through water. Lifting water through water 1,000 feet requires the same amount of energy as lifting the same water 1 foot above the surface. To harvest the energy, the tops of the kelp plants would be periodically harvested using standard kelp cutting technology. After valuable materials like algin were extracted, the kelp residues would be loaded into digesters where anaerobic bacteria would convert it into methane gas. (Methane gas is the same as natural gas.) Once produced, the gas would be piped or transported by tankers to land based natural gas pipe line grids. Digester residues would be used for animal feed and fertilizers. (374)

Although a Wilcox-like system would have the same vulnerability to natural phenomena and to terrorism as does our present energy production and delivery system, these problems can be largely avoided if aquatic plants like kelp are grown and used locally. Kelp forests grow along the coast lines of many countries. They grow by attaching themselves to rocky reefs where there is sufficient sunlight and nutrients to promote growth and where wave action is not too severe. If reefs with established kelp forest communities were expanded, the production of kelp could be increased substantially. These reefs could be expanded by depositing clean, landfill bound, materials like concrete rubble and the porcelain portion of old toilets, sinks, and bathtubs as add-ons to appropriate reefs along a coast. A similar technique has been used in China to expand its Seaweed growing Industry. Floating rafts are also being used successfully to expand China's kelp growing potential even further. (375)

Once they were in place, these materials would be stabilized through the electro-deposition of minerals. In this process, which was developed by Wolf Hilertz, a wire mesh is draped over and attached to the previously placed rubble. Next, low voltage electricity would flow through the wire mesh which would cause calcium carbonate, extracted from the water column to be deposited on to it. Over time this depositing action would stabilize the reef by fusing or cementing it together with calcium carbonate. (376) As these reef extensions stabilized, they would gradually be colonized by the neighboring kelp forest community. In addition to increasing the amount of energy available, expanding kelp systems would create many permanent jobs involved in expanding and managing kelp forests. Other jobs would involve extracting and processing kelp directly or the other life forms for which the kelp forest is the food chain base.






Energy Storage








Solar energy in the form of biomass can be stored indefinitely. Other forms of solar energy like direct solar and wind power are intermittent and therefore require storage, though not as much as might be imagined. This is especially true with a diversified system where numerous forms of solar energy are integrated, i.e., the wind may be blowing even if the weather is cloudy. Considering just wind alone, however, "an interconnected network of wind farms could supply electricity with 95 percent reliability if 24 to 48 hours of storage capacity were built into the system." (377) For reference, nuclear power plants have a reliability of around 60 percent. (378)

For openers, some solar systems inherently have less need for storage than others. Passive solar for space heating and direct solar water heating require little storage because they work quite well even in cloudy weather. (379)

The availability of wind energy and direct solar is also particularly well matched to peak energy demand. The best periods of direct solar and wind availability coincide with peak periods of industrial, commercial, and residential energy demand. The energy collected by solar thermal plants "at temperatures ranging from 350 to 1,000 degrees plus centigrade (660 - 1830+ F) "can be economically stored in commercial quantities with less than 1 percent loss per day." (380) One storage medium is molten salt which has a large heat storage capacity per volume. "Hot salt can be stored for several weeks with negligible loss." (381) Biomass, stored as wood chunks or converted to liquid fuels and charcoal, can be brought on-line to provide energy during periods when wind or direct solar are inadequate. Biomass reserves can be stretched by using solar generated electricity instead of biomass energy to convert biomass materials into alternative fuels. Biomass can be converted into gas, liquid fuels, and charcoal by heating it up in an oxygen free chamber. Solar generated electricity and direct solar energy where practical can be used as the heat source. Using solar energy to power biomass conversion processes, like pyrolysis, would save biomass energy which would have been used up in providing conversion energy. The pyrolysis of biomass consists of heating biomass in an oxygen free chamber. As the biomass is heated, volatile gases are driven off and converted into liquid and gaseous fuels. The residue from the process is charcoal which can be burned like coal to make electricity or provide direct heat. Because it is almost pure carbon, charcoal is a relatively pollution free fuel.

One of the most efficient and straightforward ways to store energy is to pump water that has already been used to generate hydro-electric power back into storage so it can flow through the hydro-turbines again. To protect downstream ecologies, the amount of water that could be used for pump storage would have to be limited. But even with such limitations, the potential for pump storage is substantial. (382)

Another way to store energy is by compressing air into tanks or underground caverns. Exhausted natural gas reservoirs would be possible locations for compressed air storage. When energy is needed the compressed air would be released to drive air turbines to produce electricity.

Battery or chemical storage is another option. Under ideal conditions batteries can deliver as much as 86% of the energy charged into them. New battery technologies on the horizon hold the promise of being even more efficient, lighter, and storing more energy in a smaller package.

Energy can also be stored in flywheels. Energy storing flywheels are gyroscope type devices mounted on magnetic bearings in vacuum chambers. Mounting flywheels on magnetic bearings and in vacuum chambers avoids friction losses from roller bearings and air. Energy is added to flywheels by speeding them up. Energy is extracted by making the flywheel into a generator by creating an electric field around it. As electricity is produced the flywheel is slowed. Pound for pound flywheels can store close to 4 times as much energy as can be stored in lead-acid batteries. (383) Additionally, "flywheels should last 10 years or more, while lead-acid batteries must be replaced every two to three years." (384)






If It's So Easy, Why Hasn't It Happened?








The question naturally arises, if it's so easy, why haven't we taken advantage of efficiency technologies and renewable energy resources a long time ago? The answer goes back to earlier discussions about true-cost-pricing.

Currently, there are a number of direct as well as indirect or hidden subsidies that support our non-renewable energy dependency. Direct subsidies include resource depletion allowances which allow resource extractors to reduce the taxes on their profits in relationship to the rate at which they deplete the resource they are extracting. In other words, the faster the extractor depletes the resource, the less they are taxed on the profits they make in the process.

Other direct subsidies in the conventional energy sector include publicly funded nuclear power research and research directed toward developing safe storage areas for spent fuel rods and other radioactive refuse.

The public is also on the hook for part of the cost of decommissioning nuclear plants at the end of their life span and for tax supported accident insurance to cover clean up and repair costs in the event of a serious nuclear power accident. According to the book Energy Future, published by the Harvard Business School, direct subsidies for conventional non-renewable energy systems could be as high as "$50 billion per year or more." (385) Other sources put direct subsidies even higher. (386)

In addition to direct supports, there are a host of indirect subsidies that make conventional energy resources appear less costly than efficiency and renewables. These costs, which are incurred when oil, coal, natural gas, and uranium are drilled for or mined, when the raw materials extracted in these operations are processed, and when these materials are used, - are paid for through tax funded environmental clean ups and repairs and increased health costs.

These costs include; crop, forestry, and fishery losses related to acid deposition (acid rain, fog. etc.), and the buildup of greenhouse gases like CO2 in the atmosphere. Health costs, like lung cancer, related to coal and uranium mining and health costs resulting from breathing polluted air or drinking polluted water also come out of the public's coffers. These costs do not show up when we purchase electricity for lighting, fuel oil or natural gas to heat our homes, or at the gas pump. Instead, they are hidden in general tax revenues, out-of-pocket health costs, and in higher prices for food and forestry products.

Pollution from conventional energy sources even causes our personal possessions to deteriorate more rapidly. Acid deposition, particulates, and other conventional energy related pollutants attack the paint and roofing on our homes, cause our clothing to wear out faster, and corrode the paint and metal on our cars. Though the connection between these pollutants and their economic effects is not often made, the money that the public pays, either out-of-pocket or through taxes, to deal with them is a direct subsidy toward maintaining the energy status quo.






True-Cost-Pricing And Solar Energy








From a true-cost-pricing perspective renewable energy systems have numerous advantages over systems dependent on non-renewable energy sources. U.S. manufactured solar systems do not cause trade balance problems like imported oil or produce pollution when they operate. With the exception of biomass, the social and environmental cost associated with renewable energy is primarily sustained during the procurement of the resources needed to create solar collectors and windmills and to maintain them after they are installed. Though it is not a point by point comparison, the replacement of the energy (in the form of electricity) that goes into the production and installation of the equipment, unique to a solar thermal plant (reflectors or heliostats, receivers, storage, etc.), is 18 months. (387)

Similarly, a solar thermal plant will recoup the energy used to create it, with the exception of "particulates (mostly dust from mining and steel making)" in the form of electricity "in about 14 months, or 5 months on a process heat basis or in terms of displaced fossil fuel." (388) In other words, a solar thermal plant operating for 30 years would produce pollution free electricity for 96 percent of the time it is in operation.

With true-cost-pricing, all the subsidies associated with the use of non-renewable energy resources would be eliminated. If this happened, market forces would quickly develop an energy system grounded in efficient energy use and renewable energy resources. It's not that efficiency and renewable energy do not have ecological and social costs, but their costs are far less than the costs associated with our present non-sustainable energy direction.






Jim Bell 4862 Voltaire St. San Diego, CA 92107