The application prospect of hydrogen energy in electric power industry

As a kind of clean renewable energy, hydrogen energy has the characteristics of storage and transport, and has important strategic significance for the sustainable development of the world economy. Hydrogen energy can be converted into electricity through a certain way, and hydrogen fuel is gradually used in generators and fuel cells.

According to the data of the International Energy Agency, the total carbon dioxide emissions generated by power generation in the world in 2014 was 32.3 billion tons, of which China has become the world's largest carbon emissions, and the annual growth of carbon emissions has exceeded the combined volume of North America and Europe.

In recent years, although China's power generation technology has made continuous improvement, such as ultra-high pressure, supercritical and ultra-supercritical units have been launched, fluidized bed combustion and integrated gasification combined cycle power generation technology continues to be used, but the entire power industry still has low energy efficiency and excessive carbon emissions. Therefore, developing a low-carbon economy and promoting the wider application of clean energy is still an arduous task.

As an important green and clean energy, hydrogen energy has the advantages of zero emission, high efficiency, high reliability and remote control. Hydrogen energy is a preferred solution to the world's energy problems and can greatly reduce carbon emissions. Hydrogen energy can not only generate heat energy through combustion, produce mechanical work in thermal engines, but also be used as a raw material in fuel cells, and can be converted into homomorphic hydrogen as a structural material. Since the 1970s, developed countries such as the United States and Japan have accelerated the pace of research on hydrogen power generation technology. At present, power generation through hydrogen energy has entered the stage of construction pilot in some developed countries. But for China's power sector. At present, it is still dominated by thermal power generation, and the application of hydrogen energy technology is less, which has lagged far behind developed countries.

Technical feasibility

Hydrogen energy is the energy released during the reaction of hydrogen and the isotopes deuterium and tritium or the state change of hydrogen. Hydrogen energy can be converted into electrical energy, mechanical energy and heat energy. The conversion from hydrogen energy to electric energy can be realized by hydrogen energy generator and fuel cell.

Hydrogen generator

Hydrogen generator refers to the generator with hydrogen as the raw material, the principle is similar to the traditional internal combustion engine, through the suction, compression, explosion, exhaust process, drive the motor to produce current output. Hydrogen generator is an environmentally friendly power generation equipment, which has the characteristics of no noise, zero emission and strong mobility.

When hydrogen generators are integrated into the power transmission line of the grid, they can cooperate with the hydrogen production device to produce hydrogen by electrolyzing water when the electricity consumption is low, and then generate electricity through hydrogen energy when the electricity consumption is high, so as to realize the rational application of electric energy and reduce resource waste. In 2013, Germany built a 500 kilowatt-level mixed energy pilot power station, the power station uses hydrogen energy as a power storage medium, the hydrogen prepared by electrolysis drives hydrogen generators in the form of combustion, and the electricity generated can directly enter the power transmission network, and can also be used for power stations to continue to electrolyze water.

PEMFC fuel cell

PEMFC fuel cell is one of the research and development focuses in the field of hydrogen energy application. The working principle is the electrochemical reaction of hydrogen and oxygen (or air) to produce water and release electrical energy, that is, the reverse reaction of electrolytic water. The structure and working principle of PEMFC fuel cell is as follows: When the anode and cathode supply hydrogen and oxygen (or air) respectively, under the action of catalyst, hydrogen is oxidized and dissociated into electrons and hydrogen atoms on the anode. Oxygen is reduced on the anode and the electrons react to form water. At the same time, electrons form a current under the connection of the external circuit, releasing electrical energy to the outside.

Compared with traditional fuel cells, energy in PEMFC fuel cells is converted into chemical energy to electric energy, and there is no combustion and heat release in the energy conversion process, thus getting rid of the limitation of the classical heat engine theory - Carnot cycle, and the theoretical utilization rate of hydrogen energy can reach 80%. PEMFC fuel cells have the advantages of fast start-up at room temperature, no electrolyte loss, high specific power and long service life.

Market analysis of hydrogen power generation

PEMFC fuel cells can be used in fixed or mobile power stations, standby peak power stations, standby power supplies, cogeneration systems and other power generation equipment. The commercialization prospects of small PEMFC hydrogen generators are also widely optimistic, and PEMFC hydrogen generators with capacity of 3 kW, 5 kW, 10 kW and even 200 kW grade combined heat and power have been applied in hotels, restaurants, commercial buildings and other places.

In terms of larger power stations, in 2010, Italy completed and put into operation a 16-megawatt hydrogen power station, the power station consumes 1,300 tons of hydrogen per hour, the total power generation efficiency is about 42%, and the annual power generation can reach 60 million KWH, not only to meet the electricity consumption of 20,000 households, but also to reduce 60,000 tons of carbon dioxide emissions per year. In 2010, South China University of Technology successfully developed and built a PEMFC fuel cell demonstration power station with an energy utilization rate of 90%. The electricity generated by the station was directly transmitted to the 380V low-voltage power grid of the university, which could meet the normal electricity demand of Huaceng International Academic Center. In addition, in 2012, Dow Chemical Company and General Motors in Texas, the United States to build a large fuel cell power generation system, the power generation system can produce 1 megawatt of electricity, and eventually able to supply 35 megawatts of electricity.

According to statistics, the proportion of hydrogen power generation in the United States in 2012 was 7.9%, which is lower than thermal power generation, hydroelectric power generation and nuclear power generation, but higher than wind power generation. In 2012, the global fuel cell system shipments of nearly 30,000 units, an increase of about 34%, compared to 2008 increased by more than 321%, of which stationary fuel cell growth is the most significant, from 2000 units in 2008 rapidly increased to 25,000 units in 2012. According to the Nikkei BP Clean Technology Institute predicts that with the application of hydrogen energy technologies, the global hydrogen energy market will gradually rise from about 7 trillion yen in 2015 to about 160 trillion yen in 2050. With the expansion of the hydrogen power generation market, hydrogen consumption will also increase, which is expected to rise from less than 1 trillion cubic meters in 2015 to 6.5 trillion cubic meters in 2050.

As early as 2006, the government has listed hydrogen energy technology as one of the priorities of the medium - and long-term scientific and technological development planning strategy, and in recent years, it has continued to increase investment in research and development and demonstration. At present, China has formed a pattern of hydrogen energy utilization from basic research to demonstration, and has initially established a hydrogen energy research and application team including universities, scientific research institutes and power enterprises. For China's power industry, hydrogen power generation technology has broad application prospects in many fields such as distributed wind power generation, photovoltaic power generation, grid energy storage and smart microgrids.

Cost-benefit analysis of hydrogen power generation

At present, the cost of fuel cell power generation is about 2.5-3 yuan/degree, while the price of traditional power generation in China is below 1 yuan/degree, for example, the cost of wind power generation is about 0.5 yuan/degree, the cost of solar power generation is about 0.8-1 yuan/degree, and the cost of thermal power generation is only 0.25 yuan/degree.

The use of platinum in heavy metal catalysts and electrolytic cell installations is one of the reasons for the high cost of fuel cell power generation. It is worth pointing out that the cost of PEMFC fuel cells is on a downward trend. According to the U.S. Department of Energy, the cost of PEMFC fuel cells in 2012 was $47 / kW, down 82.9% from 2002 and close to the U.S. Department of Energy's 2017 target price of $30 / kW.

In terms of power station construction costs, the construction cost of traditional thermal power stations is about $1300 / kW. In the context of the significant decline in the price of stationary fuel cells in North America, the construction cost of fuel cell power stations is currently $1500-2000 / kW, which is not much of a gap compared to traditional power generation methods.

Overall, due to the high cost and imperfect supporting facilities, the popularity of hydrogen power generation technology is not high. It is believed that with the continuous updating of hydrogen power generation technology, the expanding scale of hydrogen energy market, and the continuous support of the government in policy, the cost of hydrogen power generation will be greatly reduced in the future. Considering the many advantages of hydrogen power generation, the future application prospect of hydrogen energy technology in the power industry is still worth looking forward to.

Risk analysis of hydrogen power generation

Technical risk

Hydrogen storage technology is the key technology of hydrogen energy utilization, but also the difficult point. Hydrogen is a gas at room temperature and pressure, and its density is very small, only one-fourteenth of that of air. Compressed hydrogen storage is the most commonly used way of hydrogen storage. At present, the density of hydrogen storage under high pressure is low, and the weight percentage of hydrogen storage under 20.0MPa pressure is only about 1.6.

The use of composite gas tanks can improve the pressure resistance and hydrogen storage, such as glass fiber reinforced aluminum cans, carbon fiber reinforced aluminum cans, etc., hydrogen storage pressure can reach 30MPa, hydrogen storage density can be increased to 3.9 percent by weight. However, the method of compressed hydrogen storage has safety risks such as leakage and hydrogen embrittleness, and more compression work is needed to increase the pressure in the metal tank.

Policy risk

At present, all developed countries in the world are vigorously carrying out research and pilot hydrogen power generation, and some projects have been commercialized, and hydrogen energy utilization is an important content of future sustainable development and the realization of low-carbon economy. China has also introduced a series of favorable policies in the research and utilization of hydrogen energy, and most of China's investment in the field of hydrogen power generation comes from government funds. It can be seen that the government's support is a key factor in the development of China's hydrogen energy industry.

Before the large-scale application of hydrogen energy in the power industry, there are still a series of problems such as incomplete infrastructure construction, high cost of hydrogen power generation, and safety risks in hydrogen production, hydrogen storage and hydrogen transport technologies. The above problems can not be solved overnight, so in the power industry to promote the application of hydrogen energy technology, it is best to adopt the strategy of pilot and then promotion. In particular, large-scale projects should not be carried out blindly, and feasible plans need to be formulated in advance, and scientific research institutions and power enterprises should be encouraged to participate together. Thus accelerate the industrialization of hydrogen energy scientifically and rationally.

peroration

Hydrogen energy is a renewable and clean energy, which has a broad application prospect in the power industry. The use of hydrogen generators and PEMFC fuel cells and other technical means to effectively convert hydrogen energy into electricity, not only provides a feasible way to deal with the depletion of fossil energy, but also effectively solve the environmental problems caused by excessive carbon dioxide emissions.

However, the promotion of hydrogen energy in the power industry faces the following problems: hydrogen power generation cost is high, the infrastructure is not perfect, greatly hindering the marketization process; China's grid structure foundation is weak, the grid connection is unstable, and the progress of grid planning lags behind the development speed of new energy technologies; The development of hydrogen energy technology largely depends on policy guidance, and the internal power is insufficient. Therefore, when China promotes the use of hydrogen energy in the power industry, it needs to carry out scientific planning based on the current situation in China, pilot and then promote, and actively and steadily incorporate hydrogen technology into the low-carbon economic development strategy.