For efficient energy, do you want solar panels or biofuels?

● By Daniel Tan, University of Sydney ● About 80% of the world’s total energy consumption is derived from fossil fuels, with only 12.5% from renewable resources. Replacing fossil fuels with renewable energy sources derived from sunlight – such as photovoltaic solar panels, wind or biomass – is very challenging because these energy sources have a lower energy density and are generally more expensive. So if you want to maximise the efficiency of converting solar energy to renewable energy, what should you choose: solar panels or biofuels? Energy conversion efficiency of solar panels The total power from sunlight reaching the earth’s surface is about 101,000 terawatts (~2,500,000 EJ). However, solar energy is geographically diffuse – some places are sunnier than others. This makes it important to efficiently convert sunlight, capturing its energy in useful forms. The maximum conversion efficiency theoretically possible for sunlight is 93% – of all the power generated by sunlight, only 93% can be turned into electricity. Photovoltaic cells in solar panels have efficiencies of around 15–20% for converting sunlight into electricity, but won’t ever reach that theoretical 93%. They are limited to a maximum conversion efficiency of ~30%, largely because we only have technology to convert some parts of the spectrum to electricity. This limit is described by the Shockley-Queisser limit. Recent discoveries may expand this limit somewhat. Energy conversion efficiency of photosynthesis Photosynthesis is the source of the world’s food, animal feed, fibre and timber. It is also the source of biomass-based biofuels that can be a source of renewable energy. Starch and sucrose are the main products of photosynthesis. Photosynthesis occurs in cyanobacteria, algae, phytoplankton and plants and is summarised by the equation: CO₂+ H₂O + light energy = [CH₂O] + O₂ The maximum efficiency of converting solar energy to biomass energy is estimated at about: 4.5% for algae 4 ...Zum vollständigen Artikel

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