ORIGINAL CONTRIBUTION Performance Comparison of Microalgae Biodiesel Blends with Petro–Diesel on Variable Compression Ratio Engine Ajeet Kumar Soni 1 • Sunil Kumar 1 • Mukesh Pandey 1 Received: 8 July 2020 / Accepted: 12 October 2020 Ó The Institution of Engineers (India) 2020 Abstract In the present paper, the performance evaluation of a variable compression ratio single-cylinder engine with 20% blend of microalgae biodiesel with petro–diesel is presented. Microalgae biodiesel is prepared at the labora- tory scale from microalgae oil (Schizochytrium sp.), and its evaluated physical and chemical properties are observed to be comparable with petro–diesel. Further, it was observed that at a comparable compression ratio there is no signifi- cant performance variation between petro–diesel and its blended version that contains 20% of microalgae biodiesel. In addition to that, the experiment results show a reduction in the CO, un-burnt HC and smoke emissions with bio- diesel blend as compared to petro–diesel fuel. Keeping the above points into consideration, it can be said that the promotion of microalgae biodiesel for 20% blending with petro–diesel for use in existing diesel engines should be taken up. Thus, the target set to be achieved by present Indian biofuel policy of blending 5% biodiesel with petro– diesel in the existing diesel engines by 2030 seems to be on the lower side and should be considered for the upward revision. Keywords Microalgae biodiesel Á Biofuel policy Á Combustion Á VCR Á Emission Introduction Environmental concerns are major driving force for adop- tion of renewable fuels all over the world. In Indian con- text, huge import dependency on petro-fuels is another crucial factor for searching of alternative fuel sources. National Biofuel Policy (2008) [1] has proposed 20% blending of biodiesel with petro–diesel by 2017. Sinha and Agrawal (2010) [2] have also reported 20% blend as optimal one for existing engine without any modification. In the absence of smart policy initiatives on the issue of taxation, subsidy component and hassle-free long-term remunerative pricing resulted in failure to achieve the 20% blend targets set by 2017 under National Biofuel Policy (2008) [3]. Thereafter, Indian biofuel policy 2018 recom- mends blending of 5% biodiesel with petro–diesel [4]. This recommendation is in divergence with earlier blending targets and thus necessitates a relook on the blending tar- gets with technological perspective using 20% blend. At the same time, the study explores microalgae biodiesel as a possible renewable fuel in Indian context. Biodiesel is produced from natural bio-sources. Microalgae biomass is one of the emerging natural sources for biodiesel as sustainable feedstock. In India, 2% of its total geographical area is sufficient to produce 200 billion gallons of biodiesel, meeting the need of fuel for trans- portation sector [5]. Microalgae can be cultivated in saline/ brackish water/coastal seawater or non-arable land without competing for resources available for conventional agri- culture. This research paper presents the performance of a VCR engine using microalgae biodiesel blended with petro–diesel. Microalgae, due to their higher oil yield and higher growth rate, can be a feasible alternative source for petro– diesel [6, 7]. Microalgae only require nutrients and sunlight & Ajeet Kumar Soni soniajeet92@gmail.com 1 Rajiv Gandhi Proudyogiki Vishwavidyalaya, Bhopal, Madhya Pradesh, India 123 J. Inst. Eng. India Ser. E https://doi.org/10.1007/s40034-020-00183-0