Research Status and Development Prospects of Hydrogen Production

The limited reserves of fossil fuels are confronting mankind with an unprecedented energy crisis. At the same time, their combustion products are emitted into the atmosphere to accelerate the greenhouse effect. Hydrogen has the advantages of rich content, high calorific value of combustion, high energy density, high thermal efficiency, clean and pollution-free, as well as low transportation cost and wide range of uses, etc., and is considered to be the most likely to become an alternative energy source to fossil fuels. Hydrogen is an ideal energy source with the advantages of high conversion rate, renewable and non-polluting. Compared with traditional hydrogen production methods, biological hydrogen production technology has low energy consumption and is environmentally friendly, among which anaerobic fermentation biohydrogen production has been increasingly emphasized. The method and mechanism of anaerobic fermentation bio-hydrogen production are mainly introduced, the feasibility of bio-hydrogen production is analyzed, and the future development direction is proposed in the light of the current research situation at home and abroad. Global oil reserves are decreasing. The latest research shows that: according to the current global consumption trend, the ball on the harvestable oil resources can be used at most until the end of the 21st century. Petrochemicals, coal-fired energy use, but also bring serious air pollution, people increasingly feel the development of green renewable energy urgency, research and development of new energy sources was mentioned in the urgent agenda. 2000 July-August U.S. "Futurist" magazine published the U.S. George Washington University experts on the 21st century within the first 10 years of the top ten scientific and technological development trends predicted that the second is the introduction of fuel cell cars. The second one is the introduction of fuel cell cars, and the experimental fuel cell cars of Ford and Toyota will be on the market in 2004. The ninth is the challenge of alternative energy sources to petroleum energy, wind, solar, thermal, biomass and hydroelectric power will account for 30% of all energy demand. These two articles are actually new energy development and utilization. China's "Tenth Five-Year" national key development technology projects will also be new energy development and utilization of an extremely important position. At present, people on the wind, solar energy development has been considerable research, and has reached the stage of direct use, bio-energy research has also made important progress, how to store the energy obtained, how to convert energy into transportation can be used for clean and efficient energy, is an urgent solution to an important issue. Abstract

2 Biological nitrogen technology research progress

2.1 Traditional hydrogen production process methods

Traditional hydrogen production process methods are: electrolysis of water; hydrocarbon water vapor reforming hydrogen production methods and heavy oil (or residual oil) partially oxidized reforming hydrogen production methods. Water electrolysis method of hydrogen production is currently more widely used and one of the more mature methods. Water as raw material for hydrogen production project is hydrogen and oxygen combustion to generate water inverse process, to provide a certain form of a certain amount of energy, then the water can be decomposed into hydrogen and oxygen. Provide electricity to make water decomposition hydrogen production efficiency is generally 75% -85%. One of the process is simple, non-polluting, but the consumption of electricity is large, its application is subject to certain restrictions. At present, the electrolysis of water process, equipment are constantly improving, but electrolysis of water to make hydrogen energy consumption is still very high. Hydrocarbon water vapor reforming hydrogen production reaction is a strong heat-absorbing reaction, the reaction requires external heat supply. The thermal efficiency is low, the reaction temperature is high, the reaction process has a large excess of water, the energy consumption is high, resulting in a waste of resources. Heavy oil oxidation hydrogen reforming method, the reaction temperature is higher, the purity of hydrogen production is low, conducive to the comprehensive utilization of energy.

2.2 The development of new biological hydrogen production process

Hydrogen is increasingly widely used, and its demand is rapidly increasing. The traditional hydrogen production methods need to consume a lot of non-renewable energy, which is not suitable for social development needs. Bio-hydrogen technology as a sustainable development strategy in line with the subject, has attracted widespread attention in the world. For example, Germany, Israel, Japan, Portugal, Russia, Sweden, the United Kingdom, the United States have invested a lot of human and material resources to research and develop this technology. In recent years, the U.S. annual bio-hydrogen technology research costs an average of several million U.S. dollars, while Japan's annual investment in this field of research is about 5 times the U.S., Japan and the United States and other countries for this purpose also set up a specialized agency and the establishment of the bio-hydrogen development plan, with a view to the bio-hydrogen technology, basic and applied research, so that in the mid-21st century to make the technology to achieve commercial production. In Japan, the Ministry of Energy hosts the Hydrogen Action Plan, which sets the ultimate goal of establishing a worldwide energy network for the efficient production, transportation and utilization of hydrogen, a renewable energy source. The program spans 28 years, from 1993 to 2020.

The topic of biohydrogen production was first proposed by Lewis in 1966, and the energy crisis of the 1970s drew widespread attention to and research on biohydrogen production. Biomass is rich in resources and is an important renewable energy source. Biomass can be gasified and microbial catalyzed dehydrogenation methods to produce hydrogen. The physiological metabolic process produces molecular hydrogen, which can be divided into two main groups:

l, including algae and photosynthetic bacteria within the photosynthetic organisms; Rhodbacter8604, R.monas2613, R.capsulatusZ1, R.sphaeroides and other photosynthetic organisms have been carried out and taken some results.

2, such as parthenogenetic anaerobic and specialized anaerobic fermentation hydrogen-producing bacteria. At present, glucose, sewage, cellulose as a substrate and constantly improve the operating conditions and process research more. China's research in this area has also taken some progress, Ren Nanshaped Qi began to carry out research on biological hydrogen production technology in 1990, and in 1994 proposed anaerobic activated sludge as hydrogen raw material for organic wastewater fermentation hydrogen technology, the use of carbohydrates as raw material for the fermentation method of biological hydrogen production technology. This technology breaks through the biological hydrogen production technology must use pure strains and fixed technology limitations, creating a new way to use non-immobilized strains of hydrogen production, and for the first time to achieve the pilot-scale continuous flow long-term production of continuous hydrogen production. On this basis, they have successively discovered the type of ethanol fermentation with high hydrogen production capacity, invented the continuous flow biohydrogen technology reactor, initially established the theory of biohydrogen fermentation, and put forward the best engineering control countermeasures. The technology and theoretical results of the pilot study has been fully verified: pilot hydrogen production capacity of 5.7m3H2/m3.d, hydrogen production scale of up to 500-1000m3/m3, and the production cost is significantly lower than the cost of water electrolysis method of hydrogen production is currently widely used.

Biological hydrogen production process can be divided into five categories:

(1) the use of algae cyanobacteria bio-photolysis of water;

(2) organic compounds photosynthesizing bacteria (PSB) photodecomposition;

(3) organic compounds fermentation of hydrogen production;

(4) photosynthesizing bacteria and fermentation bacteria coupling method of hydrogen;

(5) enzyme catalyzed hydrogen.

Currently, fermentative bacteria have higher hydrogen production rates and lower requirements for conditions, which have direct application prospects. However, the photosynthetic hydrogen production rate of PSB is faster than that of algae, and the energy utilization rate is higher than that of fermentation bacteria, and it can be coupled with the utilization of light energy and the removal of organic matter organically, and the related research is also the most, and it is also one of the most promising methods for potential application. In the whole process of biological hydrogen production, hydrogen purification and storage is also a very critical issue. Biological method of hydrogen content is usually 60%-90% (volume fraction), the gas may be mixed with CO2, O2 and water vapor. Traditional chemical methods can be used to, such as 50% (mass fraction) KOH solution, benzenetriol base solution and a dryer or cooler. Of the several storage methods for hydrogen (compression, liquefaction, metal hydrides and adsorption), adsorption storage of hydrogen on nanomaterials is currently considered the most promising.

2.3 Problems in the current research Throughout the various stages of biotechnology research, comparatively speaking, the research on algae and photosynthetic bacteria is much more than the research on fermentation hydrogen-producing bacteria. The traditional view is that the microbial hydrogen production system (the main hydrogenase) is very unstable, and cell immobilization is possible to achieve continuous hydrogen production. To date, pure strain immobilization techniques have been used in most biological hydrogen production studies.

There are also shortcomings in this technology that cannot be ignored. First of all, the bacterial embedding technology is a very complex process, and the requirements of the production of compatible strains and bacterial immobilization material processing technology, which makes the cost of hydrogen production increased substantially; second, cell immobilization to form particles of the internal mass transfer resistance is greater, so that the cellular metabolism product particles inside the accumulation of the biological feedback inhibition and deterrent effect, so that the biological production of hydrogen capacity is reduced; third, the use of embedding agent or other substrates, which will inevitably occupy a large amount of effective space. Third, the use of embedding agent or other substrates will inevitably occupy a large amount of effective space, which limits the bioreactor biological holdings and restricts the hydrogen production rate and total yield increase. Most of the existing studies are small-scale experiments conducted in the laboratory, and the batch culture method is mostly used, while the hydrogen production using continuous flow culture is less reported. The experimental data are also short-term results, and few studies have been reported with a continuous stable operation period of more than 40 days. Even if the instantaneous hydrogen production rate is high, it is still to be explored whether long-term continuous operation can achieve higher hydrogen production. It will take many years for the biotechnology to reach the industrialized production level.

3, outlook hydrogen is efficient, clean, renewable secondary energy, its use is becoming more and more extensive, the application of hydrogen energy will be inevitable into all areas of social life. Hydrogen application is becoming more and more widespread, hydrogen demand is increasing, the development of new hydrogen production process is imperative, from the point of view of long-term planning for the application of hydrogen development of bio-hydrogen technology is an inevitable trend of historical development.

Development of China's bio-hydrogen technology needs to do the following policy and software support:

(1) Reed large publicity. People are the main body of bio-energy production and consumption, it is necessary to public opinion propaganda to strengthen people's understanding of bio-energy;

(2) increase government investment and support. New bio-energy initial commercialization phase should be carried out tax breaks and other preferential policies;

(3) Drawing on foreign experience. Fully mobilize the party and industry enthusiasm eight

(4) Strengthen the university on bioenergy education and research. People's understanding of bioenergy continues to deepen, government support to increase and research in-depth, bio-hydrogen green energy production technology will show its greater potential for development and application value.

This article is from: Guangzhou Linglong Electronic Technology Co., Ltd, hydrogen, hydrogen fuel cell (www.liongon.com)