Advances toward green fuels

Scientists have made several advances in the quest for green fuels or rather renewable energies.

They said renewable energy sources such as hydro, solar, biomass and wind have significant potential to improve and make a difference on the low level access of electricity in Nigeria.

Several researches indicate that the global mindfulness of the phenomenon of climate change together with the anticipated scarcity of conventional energy resources have prompted many countries around the world to develop a more sustainable energy systems to cater for development and growth.

According to studies, renewable energy provides a safe and feasible option for the provision of a clean and environment friendly energy. There exists a vast biomass potential in the form of bio-crops and fuel-wood, biogas, wind, solar and small hydro in Nigeria, albeit being grossly underutilized.

It is believed that the sustainable production of transportation fuels from biomass resources in Nigeria requires alternative feedstock and new technology development. Currently it is not clear that non-food biomass feedstock will be established, as current research provides no evidence for this take up.

According to a study published in the journal Renewable and Sustainable Energy Reviews, the co-processing of bio-intermediate oil with petroleum in conventional refinery infrastructure is dependent on a number of factors, among which are the feedstock type and availability, the energy potential, the capital cost of integrating the biomass pre-conversion facility to the existing conventional refinery infrastructure against the cost of a stand-alone bio-refinery, the location of the petroleum refinery and technology transfer.

The study is titled “Biomass resources and biofuels potential for the production of transportation fuels in Nigeria.”

The researchers include Juliet Ben-Iwo, Vasilije Manovic and Philip Longhurst.

They argued that transformation of Nigeria to a bio-based economy, where non-food biomass replaces crude oil, would emerge if the identified research gaps, policy shortfall and sustainability issues are addressed. They said the materializing of the 10 per cent ethanol blending in the nation’s refineries to 100 per cent domestic biofuels production in the country by 2020 would be possible if the biomass processing routes and sustainability issues are well defined.

The researchers concluded: “This review identifies the biomass resource available in Nigeria and the potential to use these resources to meet the country’s biofuel demand. Biomass is obtainable from a wide variety of sources: energy crops, agricultural crop residues, forest resources, urban and other wastes, which are distributed throughout the country based on the climatic and vegetative zones. With rising demands for clean energy and recurrent fuel scarcity, Nigeria needs to diversify its fuel supply and maximize its use of natural resources. Biofuel is an attractive alternative to substitute for fossil fuel.

“Nigeria is a net oil importer of transportation fuel. This makes the country vulnerable to volatility in global fuel prices and dependent on foreign exchange to meet its domestic energy needs. The goal therefore is to reduce the high dependence on imported petroleum by maximizing domestic biomass resources for biofuel production. However, this should be achieved sustainably with minimal environmental and socio-economic impact.

“With location of the existing petroleum refineries in the Niger Delta region of Nigeria, and the large biomass resources obtainable in the same area, it is pertinent for the Nigerian National Petroleum Corporation to consider as part of its biofuels programme if it is better to produce finished biofuels at the new bio-refineries and transport it to the existing refineries for blending, or if it would be better for existing refining infrastructures in the country to be expanded to process raw biomass into bio-intermediate oil for blending.”

Another study published in Renewable and Sustainable Energy Reviews concluded: “A significant proportion of the Nigerian population is living in rural communities, located quite far off the nearest connection to the national grid. These rural communities have no proven deposits of natural gas, crude oil or large rivers, but are, however, blessed with abundant renewable energy (RE) resources. Apart from large hydro and conventional biomass, RE resources in Nigeria are presently not given any consideration in the country’s energy supply mix and are even marginalized in future energy plans.

“Notwithstanding the fact that, Nigeria is generally blessed with ample conventional and renewable energy resources, the demand is significantly higher than the energy generated. Because of the abstruse inefficiencies associated with electric energy provision in Nigeria, it is increasingly harder for rural Nigerians to have access to the electricity service.

“The adoption of RE technologies will unambivalently lead to a better allocation of energy resources among the population, which would in turn alleviate the misfortunes of the rural communities currently groaning under acute shortage of electricity. It will eventually ameliorate the energy outlook of Africa’s most populous nation.”

The study is titled “Renewable energy potentials in Nigeria: Meeting rural energy needs”

The researchers include Mohamed Shaaban from the Centre of Electrical Energy Systems (CEES), Faculty of Electrical Engineering, Universiti Teknologi Malaysia (UTM), Johor, Malaysia; and Faculty of Engineering, Port Said University, Port Said, Egypt.

The lead researcher, J.O. Petinrin, is also from Centre of Electrical Energy Systems (CEES), Faculty of Electrical Engineering, Universiti Teknologi Malaysia (UTM), Johor, Malaysia; and Electrical/Electronic Engineering Department, Federal Polytechnic, Ede, Osun State, Nigeria.

Yet another study published in Journal of Applied Sciences and Environmental Management noted that the depleting reserves of petroleum and attendant environmental issues have led to the search for more eco – friendly and renewable fuels. Biodiesel obtained from various renewable sources have been recognized as one of the alternative fuels due to its biodegradability, high cetane number, no sulphur emissions and low volatility.

The study titled “Alternative Energy Source in a Developing Country: Biodiesel Option in Nigeria” was conducted by A.S. Uzoekwe, S. Omorogbe, and A. Hamolton Amachree.

Also, an international collaboration led by scientists at Tokyo University of Agriculture and Technology (TUAT), Japan, has developed a two-step method to more efficiently break down carbohydrates into their single sugar components, a critical process in producing green fuel.

The researchers published their results in the American Chemical Society journal, Industrial & Engineering Chemical Research.

The breakdown process is called saccharification. The single sugar components produced, called monosaccharides, can be fermented into bioethanol or bio-butanol, alcohols that can be used as fuel.

“For a long time, considerable attention has been focused on the utilization of homogenous acids and enzymes for saccharification,” said Eika W. Qian, paper author and professor in the Graduate School of Bio-Applications and Systems Engineering at the Tokyo University of Agriculture and Technology in Japan. “Enzymatic saccharification is seen to be a reasonable prospect since it offers the potential for higher yields, lower energy costs, and it’s more environmentally friendly.”

The use of enzymes to break down the carbohydrates could actually be hindered, especially in the practical biomass such as rice straw. A byproduct of rice harvest, rice straw consists of three complicated carbohydrates: starch, hemicellulose and cellulose. Enzymes cannot approach hemicellulose or cellulose, due to their cell wall structure and surface area, among other characteristics. They must be pre-treated to become receptive to the enzymatic activity, which can be costly.

One answer to the cost and inefficiency of enzymes is the use of solid acid catalysts, which are acids that cause chemical reactions without dissolving and becoming a permanent part of the reaction. They are particularly appealing because they can be recovered after saccharification and reused.

Still, it is not as easy as swapping the enzymes for the acids, according to Qian, as the carbohydrates are non-uniform. Hemicellulose and starch degrade at 180 degrees Celsius and below, and if the resulting components are heated further, the sugars produced discompose and are converted to other byproducts. On the other hand, degradation of cellulose only happens at temperatures of 200 degrees Celsius and above.

That is why, in order to maximize the resulting yield of sugar from rice straw, the researchers developed a two-step process – one step for the hemicellulose and another for the cellulose. The first step requires a gentle solid acid at low temperatures (150 degrees Celsius and below), while the second step consists of harsher conditions, with a stronger solid acid and higher temperatures (210 degrees Celsius and above).

Overall, the two-step process not only proved effective, it produced about 30 percent more sugars than traditional one-step processes.

“We are now looking for a partner to evaluate the feasibility of our two-step saccharification process in rice straw and other various materials such as wheat straw and corn stoke etc. in a pilot unit,” Qian said. “Our ultimate goal is to commercialize our process to manufacture mono-saccharides from this type of material in the future.”