**6. Conclusions**

The utilization of HDRD as CI fuel is to assist in energy security and provide sustainable and environmentally friendly alternatives to the use of PBD fuel. Though the use of biodiesel, bioethanol, and biogas have been well established with notable advantages, HDRD is to help fill the performance gap created by these renewable fuels. The use of HDRD ensures better engine performance creating more options for running a CI engine. One of the disadvantages of using biodiesel in an unretrofitted CI engine is the emission of NOx. The use of HDRD emits less NOx in most cases. In other to reduce the emission of NOx, the concentration of hexadecane and dodecane in the fuel should be increased. This can be achieved during production by altering the feedstock after production by the addition of additives. This however negates the idea of the carbon chain length effect on NOx emission [48].

In the current effort, the performance and emission characteristics of using HDRD in a CI engine have been presented. HDRD is a sustainable replacement for PBD fuels and a more effective renewable fuel than biodiesel. The application of HDRD in CI engines allows improved mechanical efficiency, BTE, and reduced fuel consumption across all engine loads and speeds. CI engines fueled with HDRD are reported to generate less CO, CO2, NOx, and PM when compared with PBD fuel. Though the production process for HDRD is more complex and expensive than biodiesel due to the high temperature and pressure involved, the overall advantage of using HDRD surpasses that of biodiesel.

Going forward, more investigations are needed to simplify the production process of HDRD to domesticate the procedure. More awareness is needed to popularize the production and utilization of HDRD among the population. There should be tax holidays and other incentives for the producers of HDRD as a way to encourage its production and utilization. Governments, across jurisdictions, should provide more funds for R & D in the feedstock, production techniques, standardization, and utilization of HDRD for various applications.

*Performance and Emission Characteristics of Hydrogenation Derived Renewable Diesel… DOI: http://dx.doi.org/10.5772/intechopen.104820*
