 Solution

ID: past-exam-of-the-short-options-paper-shared-by-prelims-and-parts-a-and-b-of-the-physics-course-of-the-university-of-oxford/2012/s4/1/4/solution

Three advantages of biomass energy are:

Sustainable regrowth can replenish the fuel and recycle its biogenic carbon, unlike depletion of fossil carbon stocks.
Chemical fuel can be stored and transported, permitting dispatchable heat, electricity or liquid-fuel production rather than requiring use at the instant of sunlight capture.
Suitable agricultural residues and organic wastes can supply useful energy while recovering value from material that would otherwise need disposal.

Three disadvantages are:

Dedicated energy crops compete for land and water, potentially displacing food production and damaging biodiversity.
Low annual areal productivity, bulky feedstock and moisture increase collection, transport, drying and conversion costs.
Combustion produces local air pollutants, and processing emissions or land-use carbon debt can undermine the claimed climate saving. A life-cycle assessment and a regrowth timescale are necessary; “renewable” alone does not prove low net emissions.

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