Introduction:

Arguably, energy is one of the most relevant addressable challenges. Due to the current Russia-Ukraine war, there is an energy crisis around the globe. Renewable energy resources have been known for decades now but they are being developed at an exponential scale. Research on 100% renewable energy systems is a relatively recent phenomenon that is directly proportional to achieving sustainable development and fighting climate change. We are aware of what is renewable energy and its advantages over the current non-renewable energy resources like fossil fuels. There are several technological developments in research to obtain better and more efficient technology in the renewable energy sector. In this article, we discuss interesting emerging renewable energy innovations to target net zero emissions.

The high dependence of global industries on fossil fuels contributes to the majority of CO2 emissions, especially in the transportation, power, heating, and industry sector. Nevertheless, many countries have implemented the application of renewable energy technologies that have led to the electrification of a majority of processes with a clean source of energy. However, due to the high dependency on fossil fuels due to their diverse applications, there are many important sectors that are yet to be transformed into electric energy.

Energy-related CO2 emissions grew to 36.3 Gt in 2021, a record high. Compared to the pre-pandemic levels in 2019, the CO2 emissions in 2021 rose to around 180 megatonnes (Mt) above the levels in 2019. The 6% increase in CO2 emissions in 2021 corresponded to increased global economic output of 5.9%. These facts explain the rise of energy-related CO2 is directly proportional to the global economic output. It clearly states that businesses running the global economy needs to adopt a net zero carbon emission, affordable and sustainable source of energy urgently, for instance, Hydrogen energy systems. In this article, we highlight a few renewable energy technologies that are currently being studied widely around the globe.

There are three emerging renewable energy technologies we will address in the following part of the article.

Green Hydrogen

The concept of using water to produce energy is too good to be true. But it is a reality. Hydrogen is a universal, light, and highly reactive fuel that can be produced from water by the chemical process of electrophoresis. This method uses an electrical current to separate the hydrogen from the oxygen in the water. If this electric current used is obtained from renewable sources we will, therefore, produce energy without emitting carbon dioxide into the atmosphere, hence called green energy. When the energy used for the electrophoresis is from natural gas, then the hydrogen produced is called Blue Hydrogen which produces carbon emissions. Next is Gray Hydrogen which is produced by using methane but emitting carbon dioxide. There are more colors of hydrogen production, but these are sone of the crucial ones. Out of these, green hydrogen is the most sustainable and renewable.

            Research and development have been exponential in making hydrogen energy available for industries and for common people. There is a startup called Enapter in Europe that has developed a technology to produce affordable hydrogen energy and the product they have introduced in the market is like the size and shape of an electricity inverter. They want to transform the energy industry into a Hydrogen economy that runs 100% on Hydrogen energy.

Figure 1: Green Hydrogen Production (https://technetics.com/ )

Artificial Photosynthesis

A very recent application of solar energy is in artificial photosynthesis. In simpler words, it is converting solar energy into chemical energy and storing it in the bonds of the fuel. Such fuels that can be produced by this process include hydrocarbons like formic acid (HCOOH), methanol (CH3OH), carbon monoxide (CO), methane (CH4), or even pure hydrogen fuel. These processes are achieved by a few device designs, including photoelectrochemical cells or photovoltaic coupled electrolyzers. Every function in this process is driven by energy extracted from sunlight photons as well as by using suitable catalysts.

The concept of artificial photosynthesis is like that of the solar panels you can see on the top of the roofs of houses and buildings. But the photovoltaic cells applied in solar panels are made such that they can utilize solar energy and convert it into electricity and use it directly. But there is a limitation to this process as it is completely dependent on weather and time. In contrast, although artificial photosynthesis devices also rely on sun exposure, the semiconductors can absorb solar energy and store it in the chemical bonds of fuel for later use. This is a process where energy is stored concentrated and inexpensively in the form of fuel, in contrast to the highly-priced and unsustainable way of storing it in batteries.

A recent development in artificial photosynthesis is a research paper that proves the use of renewable energy harvesting during wastewater treatment. In this research, microorganisms are used in a photoelectrochemical (MPEC) system. This system is integrated with microbial electrochemical Wastewater Treatment with artificial photosynthesis (APS). The figure below gives a clear prospect of the concept which could be an emerging and promising approach to tackle water-energy-carbon challenges at the same time. In this case, the concept emphasizes the significance of implementing energy recovery during WWT to achieve the carbon neutrality target as well as using that energy in running artificial photosynthesis.

     Figure 2: Recent Application of Artificial Photosynthesis (Li and Lu, 2022)  

Algae biofuels

Algal biodiesel is one of the alternative technologies to reduce the application of fossil fuels. There is a comparative advantage between algal to classical bioenergy crops. To start with, algae cultivation has much higher yields. Algae species (Schizochytrium sp., Nitzschia sp., and Botyococcus braunii) can produce approximately 50% of oil, which is then extracted and processed into fuel. Different types of fuels produced by algae are bioethanol, biodiesel, methane, aircraft fuel (kerosene), biobutanol, biogas, and green diesel.

Microalgae can easily grow in fresh and saltwater additionally also in extreme conditions. They can yield significantly high amounts of lipids that form the biodiesel produced. These microalgae are like trees that use sunlight to generate biomass in the presence of water and CO2 by photosynthesis. To produce thousands of barrels of diesel per day requires less than 1% of the land used for soybean and corn cultivation. For instance, to compare, algae yields 30% oil in dry biomass up to 58,700 L/ha/year, which is much higher compared to oilseed rape or soybeans. There are several technologies coming up in support of utilizing algae as a source of biofuel, if the reader is interested to learn more, there are many articles in the literature to go through and understand this technology.

There are many companies working and developing Algae biofuel and commercializing these biofuels for various applications. Some of the known companies are: Manta Biofuels, Viridos Biofuels, Algenol; Solazyme Inc.; Sapphire Energy; Origin Oils Inc.; Genifuels; Algae Systems; Solix Biofuels; Production Systems; Reliance Life Sciences; Alga Energy; Cellana; Culture Biosystems; Proviron etc.

These are three new trends in renewable energy systems. There are many more such renewable energy sources that are under development and could one day transform the world from fossil fuel dependent to fossil fuel independent. Renewable energies are integral part of sustainability and climate change. It is high time we start thinking to change our conventional ways of producing energy and inventing sustainable ways of living.

Reference:

1. Purchase R, De Vriend H, De Groot H. Harmsen P, Bos H, editors. Artificial Photosynthesis For the conversion of sunlight to fuel. 2015Dec;
2. Li Z., Lu L. Wastewater treatment meets artificial photosynthesis: Solar to green fuel production, water remediation and carbon emission reduction. Front. Environ. Sci. Eng. 16, 53 (2022). https://doi.org/10.1007/s11783-022-1536-5
3. Artificial Photosynthesis as a Renewable Energy Source Dr. Raj Shah, Ms. Eliana Matsil, Ms. Gabrielle Massoud, Koehler Instrument Company 12/22/21, Solar Power, Other Renewables, Photosynthesis
4. Bošnjaković, M.; Sinaga, N. The Perspective of Large-Scale Production of Algae Biodiesel. Appl. Sci. 2020, 10, 8181. https://doi.org/10.3390/app10228181
5. Amin M., Shah H.H., Fareed A.G., Khan W.U., Chung E., Zia A., Farooqi Z.U.R., Lee C.  (2022) Hydrogen production through renewable and non-renewable energy processes and  their impact on climate change, International Journal of Hydrogen Energy, 47, Issue 77, Pages 33112-33134, ISSN 03603199, https://doi.org/10.1016/j.ijhydene.2022.07.17
6. Capurso T., Stefanizzi M., Torresi M., Camporeale S.M. (2022) Perspective of the role of  hydrogen in the 21st century energy transition, Energy Conversion and Management,  Volume 251, 114898, ISSN 0196-8904, https://doi.org/10.1016/j.enconman.2021.114898