The total rate at which power is used by humans worldwide is approximately 15 TW (terawatts). The solar flux averaged over the sunlit half of Earth is 680 W>m2 (assuming no clouds). The area of Earth's disc as seen from the Sun is 1.28 * 1014 m2. The surface area of Earth is approximately 197,000,000 square miles. How much of Earth's surface would we need to cover with solar energy collectors to power the planet for use by all humans? Assume that the solar energy collectors can convert only 10% of the available sunlight into useful power

검증된 단계별 안내

Calculate the total solar power received by Earth by multiplying the solar flux (680 W/m^2) by the area of Earth's disc (1.28 * 10^{14} m^2).

Determine the useful power output from the solar energy collectors by multiplying the total solar power received by the conversion efficiency (10%).

Compare the useful power output from the solar collectors to the total power used by humans worldwide (15 TW) to find the fraction of Earth's disc area needed.

Convert the fraction of Earth's disc area needed into the actual area by multiplying it by the total surface area of Earth (197,000,000 square miles).

Convert the area from square miles to a more convenient unit if necessary, such as square kilometers or square meters, for better understanding.

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주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

Solar Flux

Solar flux refers to the amount of solar energy received per unit area, typically measured in watts per square meter (W/m²). In this context, the average solar flux over the sunlit half of Earth is 680 W/m², indicating how much solar power is available for conversion into usable energy. Understanding solar flux is crucial for calculating the potential energy that can be harnessed from sunlight.

Energy Conversion Efficiency

Energy conversion efficiency is the ratio of useful energy output to the total energy input, expressed as a percentage. In this scenario, the solar energy collectors are assumed to convert only 10% of the available sunlight into usable power. This concept is essential for determining how much solar energy must be collected to meet the total energy demand of humanity, as it directly impacts the required surface area of solar collectors.

Surface Area Calculations

Surface area calculations involve determining the total area available for solar energy collection. The area of Earth's disc as seen from the Sun is given as 1.28 x 10^14 m², which is critical for understanding how much solar energy can be captured. Additionally, knowing the total surface area of Earth helps in assessing the proportion of land that would need to be covered by solar collectors to meet global energy needs.

관련 실천

교과서 질문

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교과서 질문

A 40-lb container of peat moss measures 14 * 20 * 30 in. A 40-lb container of topsoil has a volume of 1.9 gal. (b) How many bags of peat moss are needed to cover an area measuring 15.0 ft * 20.0 ft to a depth of 3.0 in.?

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교과서 질문

Gold is alloyed (mixed) with other metals to increase its hardness in making jewelry. (a) Consider a piece of gold jewelry that weighs 9.85 g and has a volume of 0.675 cm3. The jewelry contains only gold and silver, which have densities of 19.3 and 10.5 g/cm³, respectively. If the total volume of the jewelry is the sum of the volumes of the gold and silver that it contains, calculate the percentage of gold (by mass) in the jewelry. (b) The relative amount of gold in an alloy is commonly expressed in units of carats. Pure gold is 24 carat, and the percentage of gold in an alloy is given as a percentage of this value. For example, an alloy that is 50% gold is 12 carat. State the purity of the gold jewelry in carats.

1427

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