The Natural Energy Engine™, requires no combustion, operates virtually silently, and generates no emissions. It operates by utilizing low level heat energy ~80°C suitable for many applications, from solar, geothermal, or any other heat source, including waste heat from existing processes.
The main components of the engine system are quite simple – a piston/cylinder and a heat transfer system. The cylinder contains a piston and a working fluid, and depending on the application may have a module to reposition the piston after each stroke. The heat transfer system comprises heat exchangers, a system to circulate the heat transfer fluid (typically water), and a simple circulation controller.
The key difference between a traditional combustion engine and the NE Engine is that the NE Engine relies on the transfer of heat to, and its subsequent removal from, a working fluid within the cylinder. As the working fluid is heated it expands, providing the pressure to drive the piston, and is subsequently cooled to complete the cycle.
The Company projects that engine configurations can easily be priced at 60-85% of power systems that produce equivalent output.
The NE Engine creates mechanical energy in a three step process:
Step 2: The hot water enters a heat exchanger where the heat is transferred to a working fluid. The working fluid, typically liquefied CO2, has a very high coefficient of expansion, meaning that it expands and contracts significantly, based on its temperature, while remaining in a liquid state. As the working fluid is heated, it expands, pushing a piston in the engine’s cylinder.
Step 3: Cooling water – generally in the range of 100° F lower than the input water, with varying differentials depending on the application – then enters the heat exchanger causing the working fluid to contract, readying the piston for another stroke.
In typical applications, due to the natural pressure of liquid CO2, the cylinder is constructed such that the CO2 working fluid is on one side of the piston and a pneumatic spring charged with nitrogen (N2) is on the other. Heating the working fluid results in increased pressure on the working fluid side of the piston. The hydraulic pressure of the working fluid must be high enough to overcome the starting torque (static friction) of the piston. When the pressure exceeds this point, the piston moves outward, compressing the pneumatic spring. After a predetermined time period, cooling water is sent through the heat exchanger. As the temperature decreases, the volume of the working fluid shrinks. The backpressure of the pneumatic spring helps push the piston back to its starting position.
The fundamental design of the engine provides the basis for its efficiency and economy. First, the engine has an inherent efficiency because so little energy is dissipated in heat loss and noise generation. In an internal combustion engine, for example, much of the BTU energy in the gasoline is sent out the tailpipe as waste heat, but the NE Engine can actually recycle whatever heat is not used. In part, this is because the engine operates at low temperatures – the NE Engine uses heat differentials of approximately 100° Fahrenheit to produce usable power.