What does this question mean?
'how efficient can this resource be compared to fossil fuels? '

It means:  Compared to coal, oil, and natural gas, would you need to spend
more or less on this resource to heat a house, or to heat 10,000 houses, or
to generate the electricity for a city ?

The 'efficiency' of a resource boils down to how much energy you can get
from it, use for living, and then clean up after, for a dollar.

Mantle convection is the process that drives plate tectonics. the theory of plate tectonics states that the crust is divided into plates that float on the semi molten mantle below. the circular motion of the magma as it slowly rises and falls or move though convection cells drags the plates along causing them to move. the heat source in the lamp would represent the earth's core. the core is the source of energy that drives convection in the mantle. the lava represents molten magma under the earth's surface. if the lava lamp had floating pieces they would move as the circular motion of the lava in the lamp as it rises and falls would move them along the surface. these floating pieces would represent pieces of the earth's crust. 

The answer is itprovides information about locationis a network of satellites orbiting the earth