Full Length Research Article 

Feasibility analysis of bioethanol produced from Ceratophyllum demersum L. aquatic weed utilizing solar energy  

Dmoua Kamil Hashim, Husam M. Kredy*

Adv. life sci., vol. 12, no. 3, pp. 509-514, August 2025
*^- Corresponding Author: Husam M. Kredy (Email: hmk20001999@sci.utq.edu.iq) 
Authors' Affiliations

Abstract
Introduction
Methods
Results
Discussion
References 

Abstract

Background: Biofuels have gained significant attention due to the growing demand for sustainable energy and concerns over greenhouse gas emissions. A promising candidate is Ceratophyllum demersum L., a nuisance aquatic weed common in Iraqi water systems, which potentially can be utilized in the generation of bioethanol.

Methods: In this study, the possibility of using Ceratophyllum demersum L. as raw material for the generation of ethanol was investigated through the process of acid hydrolysis accompanied by fermentation. To test the accuracy and reliability of the data, the experiments were repeated in duplicate. Solar pond systems have also been utilized to provide heat for the pre-treatment and fermentation process, hence reducing the requirement for conventional sources of energy.

Results: The findings revealed that Ceratophyllum demersum L. has high potential to serve as a feedstock for bioethanol production. The highest concentration of ethanol in the first trial was 82.48% at a 3M acid concentration and 2.5% substrate quantity and was 89.80% under the same conditions in the second trial. The ethanol yield represents percentage purity (v/v) determined post-fermentation.

Conclusion: The study findings affirm that Ceratophyllum demersum L. is a potential raw material for the production of bioethanol. Furthermore, the combination of solar thermal systems with biomass treatment maximizes overall efficiency in energy. By so doing, this strategy lessens traditional energy requirements while striving for ecological and economic sustainability through the harvesting of untapped plant material and the harnessing of solar heat, fundamental aspects to the sustainability of bioethanol production.

Keywords: Bioethanol, Solar Thermal Energy, Biofuel, Ceratophyllum demersum L.   

Introduction

With a main emphasis on lowering the reliance on fossil fuels, sustainable development has emerged as one of the most pressing worldwide objectives of the 21st century [1]. Fossil fuels are finite, non-renewable resources, and the world’s stock of these fuels is fast running out without being replaced [2]. The need of locating alternative energy sources has become increasingly pressing as fossil fuels keep running out. Furthermore, one of the most pressing issues for mankind nowadays has been climate change. Primarily driven by the great dependence on fossil fuels, this age-old problem, acknowledged since the last century, affects the whole planet. Nearly 80% of the world’s energy use is from fossil fuels [3], whose burning emits greenhouse gases, including carbon dioxide (CO2), the primary driver of global warming [4]. The effects of global warming are evident, including drastic changes to ecosystems, such as rising sea levels caused by glacial melt, and extreme weather conditions due to greenhouse effect. Reducing CO2 emissions by switching to cleaner, more sustainable energy sources is essential to offset the negative consequences of global warming and help to create a livable future for future generations. Renewable biofuels have surfaced as a viable substitute for fossil fuels in reaction to the environmental and energy crisis [5].

Living organisms such as plants, microbes, and animals contribute and produce a non-hazardous and renewable energy source known as biofuel. Among the many kinds of biofuels are biogas, pyrolysis oil, biodiesel, and bioethanol [6]. Of these, bioethanol is the most often used renewable travel fuel. Biomass is processed by means of a biochemical technique called microbial fermentation [7]. Biofuel production is the fermentation of plant or animal-based feedstocks containing fermentable carbohydrates, lipids, and sugars [8]. As they offer a realistic answer to the depletion of fossil fuels, consumer interest in liquid biofuels has risen significantly lately. Compared to gaseous fuels, liquid biofuels like bioethanol and biodiesel have higher calorific values per volume and are safer, easier to transport, and store. Furthermore, because they share characteristics with traditional petroleum-based fuels like gasoline and diesel, their application in the transportation sector could result in a significant 70 to 90% decrease in greenhouse gas emissions. Furthermore, to improve the sustainability of conventional fossil fuels, bioethanol and biodiesel are frequently combined with them [9].

Bioethanol is produced by fermentation, while biodiesel is produced by transesterification [10]. Bioethanol has garnered a lot of interest and is regarded as one of the most promising green fuels [11]. Its superior oxygen content and octane number in comparison to other fuels, as well as its sustainability and renewability, are the main reasons for this [12]. The conventional biofuel feedstocks, like corn and sugarcane, are hampered in the global bioethanol capacity due to their priority function being that of food crops [13]. This has spurred research for the discovery of alternative biomass that is not food in origin, mainly lignocellulosic materials, for the generation of ethanol. Ethanol that is produced from this raw material is second-generation (2G) fuel. The process of generation is biochemically done, where techniques for fermentation and hydrolysis convert the cellulose fraction of the different lignocellulosic feedstocks to consumable alcohol [14].

The recent literature identifies aquatic plant life as a potential lignocellulosic biomass resource for the production of ethanol [15]. The aquatic plants offer several advantages for biofuel uses: they naturally purify water systems, are less costly to process, are not in competition with food-producing resources, and have low farm inputs in comparison to traditional crops [16].

Figure 1 illustrates Ceratophyllum demersum L., commonly known as Coontail or Hornwort. As a rootless floating plant, this organism has inhabited the water bodies across the various aquatic ecosystems worldwide [17]. It is often classified as an invasive aquatic species due to its ability to cover vast areas of freshwater bodies, such as rivers and lakes. The plant’s rapid propagation and high abundance have led to various environmental concerns in both freshwater and wastewater ecosystems [15]. However, invasive plant species present significant potential for bioresource utilization due to several factors, including their high photosynthetic efficiency, fast growth rate, rich carbohydrate content, minimal land requirements, and lack of competition with food crops. The plant biomass is divided into lipids, proteins, and carbohydrates, with fermentable carbohydrate fraction capable of converting into liquid bioethanol [18].

Sunlight is one of the most abundant resources on Earth's surface. However, it is rarely considered as a primary solution to energy crises or as a "fuel" capable of improving air quality in urban areas. Thermodynamic principles indicate that the higher the temperature at which solar energy is utilized in a process, the greater the efficiency and effectiveness of the final output [19]. Solar energy is a clean and renewable energy source with the potential to drive environmental remediation and energy conversion processes. Consequently, utilizing solar-driven chemistry to address energy and environmental challenges appears to be a promising approach [20].

A steady supply of raw materials is essential for most power production methods, including electricity generated from conventional fuels or biofuels. While solar energy does not require any raw materials, advanced technologies are used to convert solar energy into usable forms. One of the various applications of solar energy is solar ponds, which provide a quick and inexpensive way to collect and store incident solar radiation. The most common type of solar pond is the salinity gradient solar pond (SGSP), which has a high storage capacity and can supply thermal energy year-round for various applications requiring low-grade heat [21].

Solar energy can also serve as a medium for biofuel production by supplying the necessary heat for processes like acid hydrolysis and fermentation. In this context, this study combines two renewable energy sources—solar energy and biomass energy from Ceratophyllum demersum—to produce clean and sustainable biofuels (bioethanol).

The primary aim of this research is to capitalize on natural resources, marking the first time biofuels have been produced using solar energy in Iraq. 

Methods