[Science] 50th Earth Day, how will hydrogen energy change the world?

2020/4/23

Yesterday is April 22,2020, and the 50th World Earth Day.

▲ —— Dennis Hayes, the father of Earth Day

 The first World Earth Day, launched in 1970 by US lawmaker and Harvard student Dennis Hayes, has become a global public movement as world environmental problems grow up and environmental awareness gradually increases. China also began to hold "World Earth Day" in the 1990s. The theme of this year's World Earth Day is "Cherish the Earth and nature".

1. Why host World Earth Day?

 The goal of Earth Day is to improve the earth's increasingly serious environmental problems by calling for the environmental awareness of the government and the public, mobilizing people to participate in the environmental campaign and promoting a green and low-carbon life.

At present, environmental problems include the extinction of forests and wetlands and lakes; greenhouse gases emitted by energy combustion cause global warming, and a series of chain reactions including melting polar ice caps, rising sea levels and drought and flood disasters the depletion of non-renewable energy such as coal, oil and natural gas; and the destruction of the ozone layer.

▲ Mother and son of a polar bear trapped on a floating ice because of melting glaciers

 Among them, the energy problem is one of the important factors leading to environmental deterioration. How to develop new energy sources and optimize the existing energy structure has become the focus of all countries in the world.

2. What are the advantages of hydrogen energy as an energy source?

Hydrogen energy is regarded as the most promising clean energy source in the 21st century, and it has the following advantages:

(1) Rich in resources

Hydrogen mainly exists in compounds, such as water and hydrocarbons; water accounts for more than 70% of the earth's surface and is a rich source of hydrogen.

(2) Various sources

Hydrogen can be produced by reforming fossil energy sources such as petroleum, coal and natural gas, or by biomass cracking or microbial fermentation; from industrial byproducts such as coking, chlor-alkali, steel, metallurgy, or by electrolysis of water. Among them, the way of hydrogen production by electrolysis by water has attracted much attention because of its zero pollution, high purity and recycling characteristics of hydrogen production, but the disadvantage is large power consumption and high cost.

(3) Flexible and efficient

High hydrogen calorific value (142 KJ / g), which is 3-4 times that of fossil fuels such as coke and gasoline of the same mass; the comprehensive conversion efficiency can be more than 85% through fuel cell;

(4) Stockendability

Where and when there is excess power, electricity or heat can be stored in the form of hydrogen and released at the right time and place, which is also the unique advantage of hydrogen in other renewable energy sources.

(5) Rich in application scenarios

 Hydrogen energy can directly provide high efficiency raw materials, reducing agent and high-quality heat source for refining, steel, metallurgy and other industries, effectively reduce carbon emission, to reduce the dependence of long-distance high-load transportation on oil and natural gas, and also be applied to distributed generation to supply and heating for family housing and commercial buildings.

3. How will hydrogen energy change the world amid the growing environmental problems?

(1) Hydrogen energy has a relatively significant effect on the realization of low-carbon energy

It is mainly manifested in the following three aspects: first, hydrogen directly replaces oil for transportation fuel; second, in the future of carbon dioxide capture and storage technology (i. e. CCS technology), hydrogen is the main product of coal gasification, actually produce coal, capture carbon dioxide, and reuse the energy of hydrogen; third, hydrogen plays a role in improving energy quality in the utilization of renewable energy. In 2007, China consumed 2.65 billion tons of standard coal, of which 206 million tons of standard coal was used in the transportation industry, accounting for 7.7% of China's energy consumption. In the future, hydrogen energy can completely replace the oil for transportation and chemical industry, which is equivalent to reducing the emission of CO2 by more than 8% from a macro perspective.(Source: MAO Zongqiang, "Hydrogen energy will become a low-carbon era" new energy darling "》)

(2) Is the hydrogen energy really clean and environmentally friendly?

Hydrogen is clean and low carbon.However, whether the production of hydrogen meets the environmental protection requirements depends on its production method.

 Li Yizhong, former minister of the Ministry of Industry and Information Technology and president of the China Federation of Industrial Economics, once expressed his opinion: " Grey hydrogen is not desirable, blue hydrogen can be used, waste hydrogen can be recycled, and green hydrogen is the direction.”

 Grey hydrogen refers to the hydrogen produced by a large amount of carbon dioxide emissions, mainly from fossil energy, coal and methanol to produce hydrogen. Every 1 kg of hydrogen produced requires 5.5-11 kg of carbon dioxide. This kind of hydrogen production is obviously not desirable.

 Blue hydrogen refers to the way to avoid a large amount of carbon dioxide emissions by capture, burial and utilization of carbon dioxide. It mainly adopts steam methane reforming technology or coal gasification and carbon capture and storage (CCS) to produce hydrogen.

Green hydrogen refers to the way to produce hydrogen from renewable energy, such as electrolysis of water to produce hydrogen is a future direction, but because of its high cost and huge power consumption, further research and development breakthroughs are needed.

4. sum up

 Hydrogen is a kind of clean energy development potential of, in improving the environment problem, the hydrogen will undoubtedly play an important role, but the development of the hydrogen also need joint efforts of mankind: such as electrolysis of hydrogen production cost optimization, industrial by-product hydrogen purification purification, abandon the use of light, hydrogenation station and fuel cell technology development and promotion, etc.

Attention to the development of new energy and the fate of the earth will become an important chapter in human history in the 21st century.CAWOLO will explore it with you.