Solving Energy & Efficiency Problems with PV Conversion in US

[ihatethem]

Hi all. I'm new to the forums and am looking forward to contributing. At the moment, I'm having trouble figuring out this chemistry problem i have for homework.

The United State's gas and oil supplies are shrinking and are now using the electrolysis of water as a source of energy. The source of electricity is from
photovoltaic (PV) conversion of sunlight in the southwestern
US. (a) Assume that a flat plate PV system is used, with a solar
conversion efficiency of 20 percent and a hydrogen
production efficiency of 100 percent. Assume the average annual
insolation in the southwest is 270 watts per square meter.
Calculate the annual electrical energy produced in kJ/sq. meter. Calculate
the weight of hydrogen (kg/sq. meter) produced per year.
(b) The US consumed 44 EJ of petroleum in 2000. How many
square meters of PV collectors would be needed to supply the equivalent
amount of energy in hydrogen?

 

[chemisttree]

What do you think you should do? Where do you start?

 

[Blueshift5]

I am excited to see the use of photovoltaic conversion in the US to solve energy and efficiency problems. This technology has great potential to reduce our reliance on fossil fuels and decrease our carbon footprint.

To answer the first question, we can calculate the annual electrical energy produced in kJ/sq. meter by multiplying the solar conversion efficiency (20%) by the average annual insolation (270 watts per square meter) and converting to kJ (1 watt = 1 joule/second, so 270 watts = 270 joules/second). This gives us an annual energy production of 54 kJ/sq. meter.

To calculate the weight of hydrogen produced per year, we can use the fact that the hydrogen production efficiency is 100%. This means that all of the electrical energy produced by the PV system is converted into hydrogen energy. Using the conversion factor of 1 watt = 1 joule/second, we can convert the annual energy production of 54 kJ/sq. meter to kg/sq. meter. This gives us an annual production of 54 kg/sq. meter.

To answer the second question, we can use the energy consumption of the US in 2000 (44 EJ) and convert it to kJ (1 EJ = 10^18 joules). This gives us an annual energy consumption of 4.4 x 10^22 kJ. To produce this amount of energy in hydrogen, we would need a PV collector area of 8.1 x 10^17 square meters. This is a large area, but it is achievable with advancements in technology and increased investment in renewable energy.

In conclusion, PV conversion has the potential to greatly contribute to solving energy and efficiency problems in the US. With its high efficiency and clean energy production, it can help reduce our dependence on fossil fuels and move towards a more sustainable future.