Analysis shows that there is enough land on Earth to grow food and fuel as well, if the crop has high productivity (yeld) – for use in liquid biofuels and for direct combustion. Direct combustion of biomass allows 24h electricity generation – Solar energy only when the sun shines and Wind energy only when the wind blows…
If we hold an empty plastic bottle under water, we can feel it pushing back. This works because the bottle is, despite seeming empty filled with air. Air is considerably lighter than water. Therefore, the water presses the air-filled bottle upwards.