Besides the fossil fuels laid down millennia ago, the earth is full of stored energy, from the sun, from its fiery interior and from the gravity it exerts and the biological food and fuel it nurtures.
Whilst fossil fuels are the most concentrated energy resource, and have served man well as a cheap fuel until now, their depletion from exponential growth in consumption now requires much more effort to find and extract them, making them ever more expensive. This now dominates the world economy since virtually everything is dependent on burning fossil fuels – from food production, water supplies, power production, manufacturing, transport and the maintenance of healthy and comfortable living conditions. All are rendered more expensive and less secure through dependence on fossil fuels.
By contrast the ambient energy stored in the ground is a permanent source of energy, obvious in some places - like Iceland with its hot geysers – and well known to science as the geothermal heat store at about 1metre below the surface everywhere.
There is therefore a sustainable source of heat energy right beneath our feet, which is very cheap to extract once a collection coil has been dug into the ground. Again as with heat pump extraction from air and water, the economics have been distorted by the apparent low cost of fossil fuels, when long term costs of fuel depletion are not taken into account.
As with other alternative energy systems, the ownership of the source of energy is local and cannot be exploited by centralized fuel and power companies.
The other energy resources of the earth are equally ubiquitous – gravity is everywhere, it has driven pendulum clocks for eons and, where it draws water down streams, drives water wheels and turbines today. The latter property is also a valuable means of storing energy in reservoirs of water for release in times of need to drive turbines at times of peak demand, or when variable alternate energy systems are intermittent in production.
The ground is also the source of minerals, which nurture plant life, the plants themselves being the ‘factories’ to convert those nutrients into cellulose through photovoltaic combination with the CO2 of the air. This is the source of bio-fuels which can take the place of fossil fuels. Whilst the quantities are limited by available land area, the cost is already comparable with today’s fossil fuels.
The only restriction on bio-fuels production is the conflict with food production, but there are production methods which make plant growth in areas unsuitable for food production, and also there is a considerable amount of waste vegetation and food that can be utilised.