The main reasons for the decrease in power of natural gas vehicles are related to the fuel's characteristics and the engine's construction.

Regarding fuel properties, gasoline is a liquid fuel, whereas natural gas is a gaseous fuel. When using gasoline, the volume of liquid gasoline compared to the intake volume is negligible. However, with natural gas as fuel, a significant portion of the intake is occupied by the gas itself, reducing the amount of air entering the cylinder and lowering the inflation coefficient, resulting in reduced engine power.

In terms of engine structure, the primary factor determining engine power is the compression ratio. A higher compression ratio leads to higher thermal efficiency and effective power. However, a higher com-pression ratio also increases the tendency for engine knocking. Therefore, the engine's compression ratio must suit the fuel's knock resistance. Gasoline's knock resistance limits the compression ratio in gasoline engines. Conversely, natural gas exhibits good knock resistance, allowing for higher compression ratios, thus enhancing power output. However, the application of natural gas vehicles is still in its early stages, and its supply is not as widespread as gasoline. Consequently, it's challenging to promote specially designed natural gas engine vehicles. Presently, most operational natural gas vehicles are dual-fuel vehicles capable of using both natural gas and gasoline. These dual-fuel vehicles haven't significantly improved their compression ratios to accommodate gasoline use. Hence, the high knock resistance of natural gas remains underutilized, resulting in decreased engine power.

Gas-fired generator sets operate by burning gas to generate energy, subsequently converting it into elec-trical energy. They fall into the following two main categories.

(1) BIOGAS GENERATOR SETS

Biogas is produced from self-built biogas tanks, providing a source of energy.

It's essential to emphasize that currently, there are government subsidies. With numerous farms established, the government subsidies surpass the money invested in biogas tanks and purchasing biogas generators. Many farms are adopting this approach.

(2) NATURAL GAS GENERATOR SETS

Natural gas generator sets, on the other hand, exclusively use natural gas for power generation. Requirements for natural gas usage in gas-fired generator sets:

The primary fuel for gas engines is natural gas, although other combustible gases like associated gas from oilfields, liquefied petroleum gas, biogas, etc., can also be used. The gas used should undergo drying and dehydration processes to eliminate free water, crude oil, and light oils. The lower calorific value should not be less than 31. 4 MJ/m3, the total sulfur content should not exceed 480 mg/m3, and the hydrogen sulfide content should be no more than 20 mg/m3. Additionally, the gas transmission pressure should be within the range of 0. 08-0. 30 MPa.