Holmes.Korejwa.Fall+2010

Solar Thermal Energy _ By Mark Holmes and Kaylin Korejwa

** What is the Problem at Hand? ** The problem is that there is an excessive amount of CO2 emissions every year that occurs all over the Earth due to the burning of fossil fuels. Solar Thermal Energy is an alternative source to prevent these excessive emissions﻿.

[] (CLIP from The Inconvenient Truth discussing CO2 Emissions)

Fossil fuel consists of oil, coal, and natural gas formed from the remains of dead plants and animals. There remains have been buried over the course of millions of years and with pressure and heat, they are converted into what we used today for energy.

The reason for fossil fuel being so limited is because creating it takes a lot of time that we do not have in order to keep up with our consumption. There is no solution to creating more fossil fuels, as the world uses more fuel that it produces, so our supply is constantly dwindling. Our dependence on fossil fuels came about because they are so cost-effective to burn and transport.

While fossil fuels are considered a non-renewable source and this is the main reason for change, the world’s reliance on fossil fuels has results in numerous accidents and the deaths of thousands of plants, animals and humans alike. For example, drilling for oil and transporting volatile liquids and gasses has resulted in the destruction of millions of acres of ocean and land.

Despite these hazards and risks associated with fossil fuels, the world is reluctant to change to other sources, as it means more time and energy spent dedicated to something which could have to be changed in the future. These changes require a considerable amount of money and time be invested, as well as educating the public on the hazards of their current energy usage while encouraging them to embrace renewable sources. Even if we cannot reduce our dependence on fossil fuels immediately, lightening the load with alternative, renewable energy sources such as wind, water, and solar power can extend the life of our fossil fuel reserve until we acquire the means to reduce our dependence entirely. By reducing our dependence on fossil fuels and relying more on renewable energy, we can prevent problems arising in the future in which the world has run out of power options and must rely on unstable and more hazardous methods of energy production, such as nuclear power.

The driving force of the problem is producing electricity by burning fossil fuels such as coal and gas emits carbon dioxide, nitrogen oxides and sulfur oxides, which scientists believe contribute to climate change. Carbon dioxide and other gases warm the surface of the planet naturally by trapping solar heat in the atmosphere. This is a good thing because it keeps our planet habitable. However, by burning fossil fuels such as coal, gas and oil and clearing forests we have dramatically increased the amount of carbon dioxide in the Earth's atmosphere and temperatures are rising.We're already seeing changes. Glaciers are melting, plants and animals are being forced from their habitats, and the number of severe storms and droughts is increasing.
 * What is the driving Force of the problem? **


 * What is Solar Thermal Energy? **

Solar Thermal Energy is a carbon-free, renewable alternative to the power we generate with fossil fuels like coal and gas. The solar panels absorb the suns heat and stores it to use it as an alternative to fossil fuels.

Solar energy, which is powered from the sun is a gigantic and unlimited resource. Once a system is in place to convert it into useful energy, the fuel is free and will never be effected by the energy markets. Furthermore, it represents a clean alternative to the fossil fuels that currently pollute our air and water, threaten our public health, and contribute to global warming. Given the abundance and the appeal of solar energy, this resource is poised to play a prominent role in our energy future.

In the broadest sense, solar energy supports all life on Earth and is the basis for almost every form of energy we use. The sun makes plants grow, which can be burned as "biomass" fuel or, if left to rot in swamps and compressed underground for millions of years, in the form of coal and oil. Heat from the sun causes temperature differences between areas, producing wind that can power turbines. Water evaporates because of the sun, falls on high elevations, and rushes down to the sea, spinning hydroelectric turbines as it passes. But solar energy usually refers to ways the sun's energy can be used to directly generate heat, lighting, and electricity.

Energy from the sun has been harnesses for thousands of years. We use this energy in three main ways and when talking about solar energy it is important to distinguish between these three types:

__Photovoltaics (PV) __  Photovoltaic solar cells, which directly convert sunlight into electricity, are made of semiconducting materials. The simplest cells power watches and calculators and the like, while more complex systems can light houses and provide power to the electric grid.

__Solar Hot Water and Space Heating and Space Heating and Cooling __  Solar hot water heaters use the sun to heat either water or a heat-transfer fluid in collectors. A typical system will reduce the need for conventional water heating by about two-thirds. High-temperature solar water heaters can provide energy-efficient hot water and hot water heat for large commercial and industrial facilities.

__Passive Solar Heating, Cooling, and Daylighting __ Buildings designed for passive solar and daylighting incorporate design features such as large south-facing windows and building materials that absorb and slowly release the sun's heat. No mechanical means are employed in passive solar heating. Incorporating passive solar designs can reduce heating bills as much as 50 percent. Passive solar designs can also include natural ventilation for cooling.

David Mills believes that solar thermal technology can supply over [|90% of grid power], while reducing carbon emissions. Furthermore, //“The U.S. could nearly eliminate our dependence on coal, oil and gas for electricity and transportation, drastically slashing global warming pollution without increasing costs for energy,”// said David Mills of solar thermal energy, chief scientific officer and founder of [|Ausra].
 * What has been done/What are people doing? **





In a recent interview broadcasted by RenewableEnergyWorld.Com, Olivier Drücke, president of ESTIF, mentions that the solar thermal potential in Europe can meet 15% of heating and cooling demand in 2030 and up to 50% in 2050. That is significant given that heating and cooling demand represents 50% of the final energy consumption in Europe (with the remaining 20% for electricity generation and 30% for transportation).

Between 1984 and 1991, the United States built nine Solar Thermal plants in California’s Mojave Desert, which currently are still providing 354 megawatts annually to Californian homes.

__Concentrating Solar Power Prospects in the Southwest United States: __
 * <span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;">Improve the grid and transmission system. Greater federal oversight of the electricity grid and/or improved coordination between grid operators will help bring CST power from the country’s prime CST areas, the Southwest to a broader area.
 * <span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;">Consider alternative investment incentives. While tax credits such as the 2008 Investment Tax Credit extension are important, they are subject to periodic and uncertain renewal, which presents a challenge to investors. Moreover, in the current economy, tax-based incentives may not be as accessible to project developers as they have been in the past. Incentives such as feed-in tariffs, widely u sed in Europe, require utilities to pay renewable energy generators a fixed, above-wholesale price for the power they produce. Thus, feed-in tariffs directly raise the price paid for renewable generation and guarantees it a buyer over a period of time—a more stable signal to investors. <span style="background: none repeat scroll 0% 0% white; color: #333333; font-family: Times New Roman; line-height: 18pt; margin: 0in 0in 0pt;">[[image:http://www.nrel.gov/csp/images/3pct_csp_sw.jpg width="825" height="401"]]

<span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;">In the Southwest United States, an enormous solar energy resource remains largely untapped. There is already more than 500 MW of concentrating solar thermal power in the United States and Spain primarily, but there is significant scope to scale up development. As Congress oversees the nation’s transition to a clean energy economy, a homegrown renewable energy technology—concentrating solar thermal power—can help cut emissions and enhance energy security with American resources.

<span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;">Today, a small number of U.S. homes and businesses use solar water heaters. In other countries, solar collectors are much more common; Israel requires all new homes and apartments to use solar water heating, and 92 percent of the existing homes in Cyprus already have solar water heaters. But the number of Americans choosing solar hot water could rise dramatically in the next few years as a result of federal tax incentives that can reduce their cost by as much as 30 percent.

<span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;">According to the U.S. Department of Energy, water heating accounts for about 15 percent of the average household's energy use. As natural gas and electricity prices rise, the costs of maintaining a constant hot water supply will increase as well. Homes and businesses that heat their water through solar collectors could end up saving as much as $250 to $500 per year depending on the type of system being replaced. <span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;">



How does Solar Thermal Energy Work? ** Solar Thermal Energy Video Clip: []

There are many methods of solar energy production, with them being either direct or indirect, with active and passive components. In mainstream solar production, there are two methods which are currently used for solar energy conversion. Both of these involve the use of a solar panel, but their energy production means are a bit different. These two methods are known as solar thermal and photovoltaic energy cell production.

The solar thermal method uses the sun’s energy to directly generate heat. This works by using solar panels to collect the sun’s heat. Then once this heat is captured it is transferred to water tanks for heating and distribution through the rest of the house. This means that production maximizes absorption of the heat generated by sun throughout the day, so energy is available for night time use as well. The tubes which absorb this energy are called thermal collectors. Currently, this is the most popular form of solar panel available on the market today, with may building designs harnessing this technology.

__<span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;">The two main ways for generating energy from the sun: __

<span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;">__Photovoltaic (PV)__-This converts sunlight directly into electricity. These solar cells are found to power devices such as watches, sunglasses and backpacks, as well as providing power in remote areas. <span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;"> <span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;"> Solar cells are the basic building blocks of a PV system. They consist of semiconcuctor materials. When sunlight is absorbed by these materials, the solar energy knocks electrons loose from their atoms. When this happens it is called the "photoelectric effect."

<span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;"> These electrons then travel into a circuit built into the solar cell to form electrical current. Only sunlight of certain wavelengths will work efficiently to create electricity. <span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;"> PV systems can still produce electricity on cloudy days, but not as much as on a sunny day.

<span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;"> The basic PV or solar cell typically produces only a small amount of power. To produce more power, solar cells (about 40) can be interconnected to form panels. PV modules range in output from 10 to 300 watts. If more power is needed, several modules can be installed on a building or at ground-level in a rack to form a solar array. About 10–20 PV arrays can provide enough power for a household.

<span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;"> PV arrays can be mounted at a fixed angle facing south, or they can be mounted on a tracking device that follows the sun, allowing them to capture the most sunlight over the course of a day. **__ PV __**

The Solar Thermal Method http://www.biofuelswatch.com/wp-content/uploads/2009/09/solar-thermal-energy.gif

<span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;">__Concentrating Solar Thermal__- heat from the sun’s rays is collected and used to heat a fluid. Then once this heat is captured it is transferred to water tanks for heating and distribution through the rest of the house. This means that production maximizes absorption of the heat generated by sun throughout the day, so energy is available for night time use as well. The tubes which absorb this energy are called thermal collectors. The steam produced from the heated fluid powers a generator that produces electricity. When combined with thermal energy storage—which enables a plant to produce power under cloud cover and after the sun has set—CST can generate electricity on demand, not just when the sun is shining. <span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;">This makes CST different from many other renewable power sources. While many renewables provide power intermittently, CST with thermal energy storage can provide around-the-clock power, potentially offering a low-carbon solution to baseload power demand. <span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;">CST, which can provide power without increasing carbon dioxide emissions, will be an important part of the energy solution in the United States.

__CST__



**Looking into the Future** <span style="background: none repeat scroll 0% 0% white; color: #000000; font-family: 'Times New Roman',Times,serif; font-size: 110%; line-height: 18pt; margin: 0in 0in 0pt;">Even though the interest in solar thermal power dropped in 1990s when prices of natural gas dropped the technology is poised for a comeback. It’s is estimated by the U.S. National Renewable Energy Laboratories that solar thermal power could, in the future, provide hundreds of gigawatts of electricity, which is equal to more than 10 percent of demand in the United States. __<span style="background: none repeat scroll 0% 0% white; color: #000000; font-family: 'Times New Roman',Times,serif; font-size: 110%; line-height: 18pt; margin: 0in 0in 0pt;">This picture shows suitable areas for Solar Thermal Energy Plants: __



<span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;">Aggressive financial incentives in Germany and Japan have made these countries global leaders in solar deployment for years. But the United States is catching up thanks to a combination of strong state-level policy support and federal tax incentives. At the state level, California is leading the way. In 2006, the state’s Public Utility Commission approved the California Solar Initiative, which dedicates $3.2 billion over 11 years to develop 3,000 megawatts of new solar electricity, equal to placing PV systems on a million rooftops.

<span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;"> Other states are following suit. Sixteen states and Washington, DC have specific requirements for solar energy and/or distributed generation as part of their renewable electricity standards. New Jersey, for example, requires that 2.1 percent of all electricity come from solar energy sources by 2021. Many more states support solar deployment by offering offer rebates, production incentives, and tax incentives, as well as loan and grant programs. Federal tax incentives are also providing a strong boost to the industry. The 2008 economic stimulus bill (Emergency Economic Stabilization Act of 2008) includes an eight year extension (through 2016) of a 30 percent tax credit, with no upper limit, for the purchase and installation of residential PV systems and solar water heaters.

__<span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;">Congress can enact legislation that will facilitate bringing it to scale. Below are specific recommendations for how Congress can help the country take advantage of CST: __
 * Enact a price on carbon. CST currently is more expensive than coal and other fossil fuel sources. Because CST is a low-carbon technology, enacting a carbon price would help the technology compete with conventional sources. Capand- trade is one mechanism for developing a carbon price.
 * Fund RD&D. Research, development, and demonstration support will facilitate cost reductions of materials and systems, including thermal energy storage, which can bring down costs to make CST competitive with conventional sources of baseload power.
 * Create a national Renewable Energy Standard (RES). Currently, some states with RES have a solar “carve out,” or a percentage set aside that must come specifically from solar. These policies have accelerated deployment of CST in those states and increased utility confidence in the technology. A national RES, including a mandate for solar, would send a market signal to invest in renewables such as CST.
 * Push for CST in international technology partnerships. China, India, and countries in the Middle East and North Africa have great potential for CST. As a promising option to reduce GHG emissions and improve energy security, CST should be a priority in international collaboration on RD&D issues. For instance, the World Bank’s Clean Technology Fund includes a program dedicated to deploying concentrating solar thermal power.

**Amount of CO2 Solar Thermal Power Produces** Solar Power produces about 21.9 million megawatt-hours of electricity per year, and at 1.0 ton of CO2 per megawatt-hour of power. Therefore, solar power offsets 22 million tons of CO2 emissions from coal power per year. This is very effective!!!!!

**Amount of Water Solar Thermal Power Produces/ Amount of Water it can Generate** Produces no amount of water pollution!!!!

**Aspects of Solar Thermal Power** <span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;">There are two ways to generate electricity directly from the sun: solar thermal power, and solar photovoltaic. Both have their advantages, and the cost of both is falling.

<span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;">__Solar thermal power__ (also known as "concentrating solar power" or CSP) is currently cheaper, and can generate electricity into the night by storing heat.

<span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;">__Photovoltaic panels__ can be used anywhere, solar thermal power only works in areas with plenty of direct sunshine.

<span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;"> Solar thermal power stations use mirrors to concentrate the sun's heat, boil water and drive a conventional steam turbine. This is a CHEAP and EFFECTIVE way of producing power/energy!

<span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;"> Solar thermal electricity has been generated on a modest scale for more than 20 years in California’s Mojave Desert, and the technology has worked without problems. New power stations have recently been built in Spain and Nevada, with more in planning or under construction. The Australian-American company Ausra, which recently established itself in Silicon Valley, has signed agreements to produce 1,000 MW of electricity for two major US utilities. Spain is building up its solar thermal power industry with a special feed-in tariff. India has recently announced plans for initial incentives to encourage the development of CSP there.

<span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;">The amount of energy from the sun that travels to the Earth's surface is enormous. All the energy stored in Earth's reserves of coal, oil, and natural gas is matched by the energy from just 20 days of sunshine. Outside Earth's atmosphere, the sun's energy contains about 1,300 watts per square meter. About one-third of this light is reflected back into space, and some is absorbed by the atmosphere (in part causing winds to blow).

<span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;">By the time it reaches Earth's surface, the energy in sunlight has fallen to about 1,000 watts per square meter at noon on a cloudless day. Averaged over the entire surface of the planet, 24 hours per day for a year, each square meter collects the approximate energy equivalent of almost a barrel of oil each year, or 4.2 kilowatt-hours of energy every day. Deserts, with very dry air and little cloud cover, receive the most sun—more than six kilowatt-hours per day per square meter. Northern climates, such as Boston, get closer to 3.6 kilowatt-hours. Sunlight varies by season as well, with some areas receiving very little sunshine in the winter. For example, a one square meter solar electric panel with an efficiency of 15 percent would produce about one kilowatt-hour of electricity per day in Arizona.

<span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;"> The best place for generating solar thermal power is dry regions that have little cloud cover, as the power stations need direct sunshine. Best of all are <span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;"> deserts, which have the advantage that there is plenty of land that is not being used for other purposes.

__<span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;">Some of the bests places throughout the world for generating solar thermal power are shown on the map below: __



**<span style="color: #000000; font-family: 'Times New Roman',Times,serif; font-size: 110%;">How Critics Would Discuss Solar Thermal Power ** __**<span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;">Cost: **__ <span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;">Solar energy is more expensive than other renewable energy sources and fossil fuels. The cost of a two-kilowatt (kW) solar energy system is approximately $45,000, and it cannot fulfill more than half of a typical American household's requirements. So, it is not as useful when it is compared to electric generation costs and other fuel sources, such as coal and gas. Furthermore, solar energy prices vary according to geographical variation in the amount of light available. Photovoltaic power is driven up in price by the high costs of the materials and the manufacturing process.

<span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;">Photovoltaic cells only have a short lifetime. They are expensive as well. The initial set up cost is high. The price of solar thermal systems for residential use varies, depending on the size of household it costs between $8,000 and $10,000 for a 1kW system anywhere in the United States. In 2010, a conventional water heating system that uses gas or electricity would be cheaper ($2,000 to $4,000).

__<span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;">Efficiency: __
<span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;">Although the technology has been gradually improving, solar energy is not efficient. The most efficient photovoltaic systems reach an efficiency of about 30 percent. Concentration technologies, such as parabolic troughs (a kind of solar thermal energy collector), reach 20 percent efficiency.

__<span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;">Storage: __
<span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;">Solar energy can only be used intermittently, according to the weather and time of the day. There is no adequate means of storing the energy for later use, although technologies are being developed. The current storage equipment is currently expensive and can contribute 70 to 80 percent of the cost of a system if it is required.

__<span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;">Size and Appearance: __
<span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;">Some homeowners associations have attempted to prevent people from incorporating solar energy technologies into their homes, citing concerns about damaging the neighborhood's aesthetic appeal. People have also objected to large solar plants that would cover large areas of ground.

__<span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;">Hazardous Materials: __
<span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;">The manufacture of photovoltaic cells involves the use of toxic and hazardous chemicals. These present a risk to workers during production and are an environmental hazard. The manufacturing process produces a small amount of potentially harmful waste that contains such chemicals as selenium and cadmium. The solar panels themselves contain these toxic materials too and need to be disposed of carefully at the end of their lifetime.

**<span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;">What would it take to make Solar Thermal Energy on a larger Scale? ** <span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;">Studies in the US have calculated that if an area in the Southwestern United States 92 miles by 92 miles square were to be covered with solar thermal power stations, it would produce as much electricity as the entire US produces today. Naturally, the power stations do not all have to be built in one location and not all of a country’s power needs to come from one technology.

**Who uses this technology?** There are more architects and contractors realizing that the value of passive solar is very great and are starting to incorporate it into buildings. Solar hot water systems can compete economically with conventional systems in some areas, and federal tax incentives are making them even more affordable for homes and businesses.

Thermal Energy’s World’s Fuel/Energy Supply <span style="font-family: 'Times New Roman',Times,serif; font-size: 110%; margin: 0in 0in 0pt;">The Thermal Energy’s World supply is would most likely be described as well-developed. However, at the same time the World supply could be described as a work in progress. Although there has been significant progress from the beginning of Solar Thermal Energy in the late 1900’s, there is still a lot of improvements and expansion possible for this technology in the twenty first century. Regardless, it is expected that the growth and use of this technology is imminent.

<span style="font-family: Arial,Helvetica,sans-serif; margin: 0in 0in 0pt;">

**<span style="font-family: 'Times New Roman',Times,serif; font-size: 110%; margin: 0in 0in 0pt;">How can we change how Thermal Energy is used? ** <span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;">At present the solar thermal power plants are still more of in the experimentation stages, though a few commercial solar thermal power plants have also been installed. In future there are greater chances of erecting solar power plants of around 10 MW capacities. The solar power plants hold a great promise for our future power requirements. A number of small solar thermal power plants installed in various parts of the country are a definite possibility in the near future. These can be installed by the government or private agencies or in partnership between the two.


 * What People don't usually know about Solar Thermal Energy**

__<span style="font-family: 'Times New Roman',Times,serif;">SOLAR ENERGY: __

<span style="font-family: 'Times New Roman',Times,serif;">It's a fact that all life depends on and comes from the sun The production of oxygen and food would be impossible without solar energy. Farmers know the value of a large field with a plentiful supply of sunlight, and now individuals all around the world are taking this boundless source of diffuse energy more seriously as the finite supply of fossil fuels dwindle. <span style="font-family: 'Times New Roman',Times,serif;">Today less than 0.1% of our heating, transportation and power energy comes from direct sunlight although it is now possible to meet all our energy needs with this simple, renewable resource.

__<span style="font-family: 'Times New Roman',Times,serif;">SOLAR HOUSE: __

<span style="font-family: 'Times New Roman',Times,serif;">A solar house is any house that makes good use of the suns energy. It's a solar energy fact that an ordinary house becomes a solar house when it gains more energy than it looses. Do you think the addition of skylights and large picture windows facing south make an ordinary house into a solar house? If these additions add a net heating value to a house that might be so, but if they lose more heat than they gain that will not be the case. passive solar greenhouse additions can transform ordinary houses into solar houses, but these additions are best suited for arid sunny areas. Active solar, hydronic systems are best suited for cold climates where sunlight is minimal and extended heat storage is critical.

__<span style="font-family: 'Times New Roman',Times,serif;">SOLAR COLLECTORS AND SOLAR PANELS: __

<span style="font-family: 'Times New Roman',Times,serif;">Solar Collectors transform short wavelengths into long wavelengths and trap this energy in the form of heat which is transferred and transported into a heat storage vault. Solar panels convert selected wavelengths of light into electricity.

__<span style="font-family: 'Times New Roman',Times,serif;">ENERGY IN SUNLIGHT: __

<span style="font-family: 'Times New Roman',Times,serif;">The energy from the sun varies from place to place and is very dependent on weather conditions. Without an atmosphere 1.4 KW/m2 per hour is available, but with an atmosphere we can only count on 1KW/m2 per hour in the absence of clouds. So, if asked how much 3 hours of sunlight on one square meter is worth what would you say?

__<span style="font-family: 'Times New Roman',Times,serif;">$ VALUE OF SUNLIGHT $: __

<span style="font-family: 'Times New Roman',Times,serif;">How much is one hour of sunlight on three square meter worth? Let’s see, if we’re talking about electricity and we say that electricity is worth $0.10 per KWH than 3KWH’s are worth $0.30. The problem is that PV panels have a radiant energy conversion rate of about 20% or less so three hours of sunlight on one square meter of a solar panel is worth less than $0.06 <span style="font-family: 'Times New Roman',Times,serif;">How about heat? How much is 3 hours of sunlight on one square meter of a solar collector worth if we’re talking about heat? Well 1KWH = 3400 BTU so 3KWH = 10,200 BTU. Since one gallon of fuel oil contains 150,000 BTU 10,200 BTU’s are the equivalent of .07 gallons of fuel oil. <span style="font-family: 'Times New Roman',Times,serif;">Now if fuel oil is selling for $2.00/gallon which it soon will be the value 10,200 BTU’s is about $0.14. You might think this is an unfair assumption since we're not taking into account the heat conversion efficiency factor like we did with the solar panel. I’m glad to see you’re paying attention and you are right about this. The heat transfer efficiency of a solar hot water system is between 50% and 70% the same as oil burner heat transfer efficiency. Since the heat transfer efficiency for an oil burner is about the same as solar collector and the price of oil is $2.00/gallon than the value of 3 hours of sunlight on one square meter is worth actually $0.14.

<span style="font-family: 'Times New Roman',Times,serif;">The surface area of the roof is 1000 sq ft or 95m2. <span style="font-family: 'Times New Roman',Times,serif;">The solar energy available (for north central USA ) over the period one year on one square meter is 1500KWH. So on 95m2 we’d have:95x1500 or 142,500KWH or 484,500,000 BTU or the fuel oil equivalent of 3,230 gallons of #2 fuel oil. At $2.00/gallon our solar roof could save us as much as $6,460/yr. If half this energy is used for heating and half is used for electric power we could meet the residential requirements for energy independence. The question that you should now be asking is: How much would a house like this cost?

__<span style="font-family: 'Times New Roman',Times,serif;">$ COST OF SOLAR ENERGY $: __

<span style="font-family: 'Times New Roman',Times,serif;">Let’s take a close look at the cost requirements for a typical energy independent house in a northeastern area of the United States where the total energy bill is $3,500/yr. Let’s use $2,000 for heating and hot water and $1500 for electricity.

__<span style="font-family: 'Times New Roman',Times,serif;">ELECTRICITY: __

<span style="font-family: 'Times New Roman',Times,serif;">We’ll need to produce 15,000KWH’s to meet our yearly household electrical requirements. That’s about 40KWH per day. Since an average of 4KWH/day is available we’ll need a 10KW system to meet our yearly electrical requirements. The electricity produced by this 10KW system would have a value of about $4.00/day and require about twenty five 2 m2 panels that would occupy a surface area in excess of 600 square feet. An installed system like this could easily cost $100,000 at $10/watt. Incentive rebates could cut this cost in half, but even at a cost of $5/watt the payback period would be about 30years. If your good friends with an electrical contractor or if you do your own work you might be able to do a little better, but this is still a major investment for a product that has a live expectancy of 20 years. If the price per watt comes down to $1/watt or the price of electricity increases to $1/KWH I’m sure the ugly power lines that cut across our towns would soon be replaced by roofs decorated with PV panels. Until that time I’ll be exploring the possibilities of solar thermal energy

__<span style="font-family: 'Times New Roman',Times,serif;">HEAT: __

<span style="font-family: 'Times New Roman',Times,serif;"> For our well insulated house in the north east we’ll need 1000 gallons of oil per year. Some people will need more, but remember our budget is only $2,000/year for heat and hot water and we’re paying $2.00/gallon. OK the first thing we need to do is convert 1000 gallons of fuel oil into an energy equivalent expressed in terms of KWH’s. You should do this with me to make sure my calculations are correct. I like to round my numbers off to keep things simple. I hope you don’t find this confusing. <span style="font-family: 'Times New Roman',Times,serif;">1000 x 150,000 = 150,000,000 BTU <span style="font-family: 'Times New Roman',Times,serif;">150,000,000 BTU/3400 = 44,200 KWH <span style="font-family: 'Times New Roman',Times,serif;">442,000 KWH is our heat energy requirement for a year. <span style="font-family: 'Times New Roman',Times,serif;">Since 1 m2 collector will harvest 1500 KWH/year. <span style="font-family: 'Times New Roman',Times,serif;">44,200 KWH will require a surface area of 29.5 m2 to harvest this much energy. Since winter sunlight is more difficult to come by than summer sunlight lets change this estimate to 40 m2. Since most commercial collectors are 2 square meters you’d need 20 of them spread out over an area of 450 square feet to collect this much heat. This many commercial collectors installed with a sufficient number of commercial solar hot water tanks and a radiant heating system would cost about $100,000. If you built and installed your own solar heating system it would cost you about $10,000.

__<span style="font-family: 'Times New Roman',Times,serif;">SUMMARY: __

<span style="font-family: 'Times New Roman',Times,serif;">To summarize. I am saying that it will typically cost a person between $100,000 and $200,000 to convert their house into an energy independent house using commercially available solar application retrofit products and commercial installers. Even at a cost of $200,000 this kind of retrofit may not be feasible if the roof is too small or oriented in the wrong direction. Sounds like a lot of money huh? It is a lot of money. This is why most people don’t take solar energy seriously. You could dabble with a few solar toys if you like, but if you are seriously interested in declaring energy independence at a reasonable price you should consider designing and building an energy independent house from the ground up for not much more than a conventional house. The more involved you get with the process the more you will save. <span style="font-family: 'Times New Roman',Times,serif;">Why solar energy so expensive: <span style="font-family: 'Times New Roman',Times,serif;">There are many reasons why solar energy is so expensive. I’ll try to shed light on a few of them. <span style="font-family: 'Times New Roman',Times,serif;">a. Competition is minimal. <span style="font-family: 'Times New Roman',Times,serif;">b. Government regulations will not allow house owners to install their own systems. <span style="font-family: 'Times New Roman',Times,serif;">c. Architects are reluctant to approve innovative unproven solar house designs. <span style="font-family: 'Times New Roman',Times,serif;">d. Builders find that it is not profitable for them to spend excessive architectural fees on designs that are not mainstream and salable. <span style="font-family: 'Times New Roman',Times,serif;">e. Our government, who should be demonstrating a leadership position in the promotion and use of solar energy, is the primary offender of energy conservation and has no interest in the promotion of a sustainable culture that might threaten the aristocracy. <span style="font-family: 'Times New Roman',Times,serif;">f. The price of oil is maintained at an artificially low price by government subsidies and special interest groups. <span style="font-family: 'Times New Roman',Times,serif;">g. Most people are too busy dealing with the problems of day to day survival to be concerned with the headache of a long range investment like solar energy. <span style="font-family: 'Times New Roman',Times,serif;">h. Fossil fuel oil corporations, who control our economy are doing all they can to discourage the proliferation of alternative energies. <span style="font-family: 'Times New Roman',Times,serif;">i. We have become addicted to fossil fuel energy concentrates the way a child becomes addicted to candy.

__<span style="font-family: 'Times New Roman',Times,serif;">Why other countries use more solar energy than the America: __

<span style="font-family: 'Times New Roman',Times,serif;">Oil is three or four times more expensive in many non American countries. Solar energy alternatives are less expensive than fossil fuels and grid power. It’s as simple as that. If you had to pay $7 gallon would you consider the possibilities of solar?

__<span style="font-family: 'Times New Roman',Times,serif;">Could you install my own solar electric system? __

<span style="font-family: 'Times New Roman',Times,serif;">Legally speaking, most state regulations prohibit individuals from installing their own system even though these installation fees are excessive. If you do install your own system you could easily cut your bill in half, but than you wouldn’t be entitled to a rebate.

__<span style="font-family: 'Times New Roman',Times,serif;">Could you install my own solar hot water system? __

<span style="font-family: 'Times New Roman',Times,serif;">Legally speaking, most state regulations prohibit individuals from installing their own solar hot water system but the rebates are at best minimal and very difficult to apply for. The penalty for installing your own system could be as harsh as an order to remove it when you sell your house. If you think you have the necessary plumbing skills go for it, but don’t expect your insurance company to cover any plumbing damages.

__<span style="font-family: 'Times New Roman',Times,serif;">Could you heat my house with sunlight? __

<span style="font-family: 'Times New Roman',Times,serif;">Most definitely. If you live in the south west all you need is a simple passive solar greenhouse. Northern climates require lots of insulation as well as an entire solar thermal roof dedicated to the process of gathering heat and an enormous heat storage vault for storing it. The labor and materials required to heat a house with sunlight are minimal compared with the government regulations and the building permit headaches.

__<span style="font-family: 'Times New Roman',Times,serif;">How does a solar cell work? __

<span style="font-family: 'Times New Roman',Times,serif;">I can show you how it works and even show you how it’s made, but the equipment needed to produce a practical solar cell is very, expensive so unless you’re a millionaire with a bottomless pit of money or a talented, dedicated machinist I’d shoot for a different profession.

__<span style="font-family: 'Times New Roman',Times,serif;">How does a solar hot system work? __

<span style="font-family: 'Times New Roman',Times,serif;">Most hot water systems are designed to preheat water before it enters a conventional hot water heating system. The five parts of the system include a collector, a pump, a heat storage tank and a differential thermostat.

__ How does a solar heating system work? __

hydronic solar heating systems work the same way as solar hot water systems except that the stored hot water is used for house heating rather than domestic hot water systems. Hydronic solar heating systems are typically ten or more times larger than domestic hot water systems. In mild, sunny areas the hot air from solar greenhouses are often used for house heating, but hydronic systems are more suited for cold climates.

__ Is an integrated system possible? __

Solar heating and solar hot water systems may share the heat from the same heat storage vault. Radiant solar heating radiant heating is a method of heating slab of material. Since the temperature of stored solar hot water is low radiant heating is preferred. This is true because the large surface area of a radiant heating system is required to obtain the same results of a conventional concentrated heat source. A warm floor is a warm house. Radiant solar heating systems circulate hot water through a network of plastic tubes into the flooring of a concrete slab. Plastic tubes are used because they will not corrode in the presence of concrete.

__ Solar greenhouse retrofit __

A retrofit is sort of an after thought. After a house is built the owner decides to add something. If a house is oriented properly and landscaping permits a fair amount of sunlight into the proposed solar greenhouse a practical method of heat gain is possible. Solar greenhouses are different than standard greenhouses in that they have a net heat gain effect on the house.

__ What is an energy independent house? __

An energy indepentdent house is exactly what you think it is. It’s a house without power lines hanging over the back yard. It’s a house without an oil tank attached to the side of the house, buried in the ground or occupying valuable basement space. A well planned solar house can supply all the electrical household needs and 80% of the heating requirements. Additional heating requirements can be supplemented with a well insulated, wood stove designed to burn (wood, cardboard, cereal boxes, milk cartons, and other household waste products) at a high temperature. High temperature burning results in complete oxidation without polluting the atmosphere. A well insulated wood stove releases most of its heat through the chimney. This is where heat should be collected and added to the multi tank heat storage vault.

__ What is a multi-tank heat storage vault? __

A heat sorage vault system is a practical, efficient, method of collecting, storing and distributing large quantities of heat at low cost.

__ What is a solar thermal roof? __

A solar thermal roof is basically a roof converted into one giant collector. A solar thermal roof 50’x20’ or 1000 sq ft could easily harvest the fuel oil equivalent contained in 3,000 gallons of fuel oil/year. The materials needed to make a solar thermal roof of this size cost about $4,000. It takes two men two days to assemble. A 3,000 gallon heat storage vault takes a full day to build. The plumbing and radiant heating system could take another day. The material cost of the entire system would be about $6,000. The problem is that most roofs are not oriented south with the steep pitch needed to maximize winter heat gain so a radical roof and house reconstruction might be necessary to make a solar thermal roof practical. This is why more thought should go into new construction and house builders should be educated about the possibilities of a solar thermal house.

__ What is a solar thermal power? __

Commercial solar power plants use superheated steam to generate electricity. A residential solar hot water storage vault stores hot water system operates at a much lower temperature. Is it possible to use this low temperature to generate electricity? As long as a there's a temperature difference electricity may be generated. Sterling engines can operate at temperature differences of less than 150 F although the power they generate is not very significant. To increase the efficiency of power generation and use the waste heat to generate hot water for house heating we need a low temperature turbine generator but that could take a lot of government research dollars to develop. Another possibility is that we could pool our efforts and come up with with a viable low temperature solar thermal engine.


 * References Cited **

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