According to the proponents of the 'Peak Oil' theory, the world is expected to face severe oil shortages in the near future. Then, how can mankind meet its energy needs?

Peak oil is the point in time when the maximum rate of global petroleum extraction is reached, after which the rate of production enters terminal decline. The concept is based on the observed production rates of individual oil wells, and the combined production rate of a field of related oil wells. The aggregate production rate from an oil field over time usually grows exponentially until the rate peaks and then declines—sometimes rapidly—until the field is depleted. This concept is derived from the Hubbert curve, and has been shown to be applicable to the sum of a
Also, everything is transported by oil (gas/diesel) and will go up in price because of the increase in shipping costs. Many of our homes are heated by heating oil and natural gas. Most electricity is produced from natural gas (propane is liquefied natural gas or LNG) or coal which requires oil (gasoline and diesel fuel) for mining and shipping. Fertilizers and pesticides require oil and/or natural gas for manufacture. Giant agricultural corporations can not feed the world without tractors, fertilizers and pesticides. Industries will not be able to produce our consumer products without oil. Nations will begin fighting (have begun fighting) for oil and natural gas to save their economies. As people are unable to pay higher prices for manufactured products, employers will begin layoffs and unemployment will increase. The unemployed will not be able to buy, and businesses will close creating more layoffs and homelessness. Protests, riots, and crime will increase and the response will be martial law, a police state, and government seizure of weapons, foods, and medicines for emergency relief and control could happen. All of the efforts to control and protect remaining resources will ultimately fail. This spiral of war, failing businesses, and social decay will get worse in all nations as oil and natural gas resources are depleted. Because of easy access to fossil fuel energy there is significantly more population