Energy governs the world - our development is driven by energy transformations. In order to ensure optimal solutions for all-embracing energy issues, we elaborated scientifically based (mainly on Thermodynamics) Strategy of Sustainable Energy Development (3D-Strategy), founded on three principles: Decentralization, Diversification and Decarbonization. Our credo is - only complex, integrated approach can ensure optimal, sustainable solutions for all energy related problems. It is because the Universal law of energy conservation integrates all nature phenomena. Thermoaccumulation is an indispensable component of energy-efficient systems. It refers to accumulation of both - high-potential, and low-potential thermal energy (secondary energy, or “waste” heat). Intermittence of renewables (especially, of solar radiation), necessity of daily and seasonal temperature variations’ utilization - these are additional arguments for thermoaccumulation development. From large amount nomenclature of thermoaccumulators we especially highlight two - most important - types of thermoaccumulators: related to accumulation of natural (“winter”) cold, and the secondary energy (“waste heat”) accumulation, coming from the thermal machines (heat engines). Both mentioned types of thermoaccumulators have extremely large potential field of application and - respectively - can drastically change (improve) energy problems solving. For both cases we propose efficient principles and constructions for thermoaccumulation. Intelligent application of the advanced low temperature (cold) accumulators permits realization of the competitive advantages for the relatively high latitudes’ countries - with continental climate. These advantages derive from Thermodynamics (apropos, nowadays - mainly because of the adequate thermoaccumulation technologies absence - seasonal cold and heat are usually irrationally treated as important disadvantages, which finally cause immense damages to economy). We developed non-traditional thermal machine, based on the frozen water (ice) expansion. Unique property of the frozen water to expand by approximately 9% - ensures obtaining of the additional high-potential energy during freezing process, the quantity of which is a strong function of the operating pressure. Large-scale application of the low-temperature thermoaccumulation can decisively improve the economy indices for all the related technologies air-conditioning, freeze- and vacuum drying, cryoconcentration, cold (refrigeration) storage, etc. The original solution of the “active wall” is applied for the efficient on-board utilization (accumulation) of the “waste heat” coming from the transport’s heat engines. Rational utilization of this - relatively low-potential - thermal energy of a really huge quantities can change entire energy issue, and first of all - the pressing district heating task. It is worth to mention different adsorbents and absorbents (silica-gel, CaCl2, LiCl, LiBr, etc.) - as non-traditional, open-cycle accumulative heat generators. Such accumulative heat generators also can be treated as no-movable parts accumulative open-cycle heat pumps.