關于在中國鋼鐵工業降低能耗和減少能源成本的研究

摘要：鋼鐵工業在中國屬于高能耗工業，煤和電又是鋼鐵制造的主要能量來源。目前鋼鐵工業在中國的工業化進程中由于中國經濟的轉型而處于轉型期，而鋼鐵需求近幾年來急速增長也進一步擴大了能源需求。另一方面，由于政府的宏觀調控，煤炭和電的價格自1980年以來也在快速增長。巨大的能源需求導致高能耗，而越來越高的能源價格也進一步增加了鋼鐵制造的成本。激勵于降低能耗和減少能源成本的緊迫需求，本文構建了系統動力學模型來幫助探尋相關政策，目的是為了尋找鋼鐵行業在其轉型期內緩解能源問題的方法。此模型有助于學習一個復雜的動態問題，因此能更好的幫助理解能源相關政策的可行性及有效性。測試結果表明大部分可選擇的政策仍具有成本效益。然而，如何去實踐操作這些政策措施依舊是關鍵，因為某些政策諸如能源稅和研發補貼的可行性在現實世界中仍然面臨質疑。另一個結論發現：發展回收廢鋼的技術有可能有效的緩解二氧化碳排放，且可操作性相對較強。

關鍵詞：中國鋼鐵工業 系統動力學 能源價格 能源需求 轉型期

Abstract:Chinese steel industry is one of the energy intensive industries in China. Coal and electricity are the two main energy sources for steel making. Steel industry in China is experiencing its transition period because of economy transition during the industrialization period. Steel demand has increased significantly in recent years， which correspondingly enlarges the energy demand. On the other hand， energy prices of coal and electricity have been increasing dramatically since 1980 because of the macro-control from the government. Large energy demand leads to high energy consumption and high energy price raises the energy expense of steel making. Motivated by the need to reduce energy use and energy expense， a System Dynamics based model is built to investigate policies in order to help Chinese steel industry ease energy problems during its transition period. The model helps to foster learning about a dynamically complex system， and thus contributes to a better understanding on the effectiveness， validity of energy policies. Results show that most of the investigated policy options are cost-effective. However， implementation remains a critical issue， the viability of energy tax and RD subsidy is still questionable in the real world. Developing the technology of recycling scrapped steel is found to be useful in limiting carbon emission with comparatively easy implementation.

Key Words: Chinese steel industry， System Dynamics， energy price， energy demand， Transition

Introduction

Steel industry is one of the energy intensive industries in China， and is responsible for the country’s 15% of the total energy consumption and corresponding carbon dioxide emissions. Iron and steel production consumes a large quantity of coal， especially in China at its early stage of industrialization where outdated， inefficient technologies are extensively used to produce iron and steel. High energy demand during industrialization transition period and rapidly rising energy price due to resource scarcity and potential government policy adjustment are two challenges for steel industry. The dynamic condition allows us to use some tool which can capture the above features and the interrelationships among them.

1. PROBLEM BACKGROUND

The Chinese steel industry is one of the high energy-intensive industries; the energy problems in steel industry became serious in recent years. Three major issues are of special concern.

1.1 Rapid Development of Steel Industry and Correspondingly High Energy Demand

1.2 Dependence on Coal and Electricity and Problematic Price Increase

1.3 Transition Problem

Rapidly increasing steel demand leads to high energy demand while continuous increasing energy price will lead to high energy expense. The system has already entered into a so-called “transition period” as a result of industrialization transition and price increase since 1980. The transition period will terminate when China has entered the maturity period of industrialization. During this transition period， the steel industry may have to invest more on energy efficiency technology， adjust the steelmaking process structure in order to reduce energy use and expense.

Two main solutions are studied in this research to ease the transition problem:

-Developing Energy Efficiency Technology

“Energy efficiency technology” here refers to efficient utilization of natural resource， waste water， heat and gas recycling， continuous casting， reducing ore to steel ratio and hot metal to steel ratio and any measure that can reduce energy consumption for steel making.

-Improving Steelmaking Process

Electric arc furnace (EAF) using scrap is a process in which， the coke production and pig iron production are omitted， resulting in much lower energy consumption. EAF develops quickly with the development of steel industry， but the share of EAF increases slowly. Only sufficient scrapped steel resource can ensure the possibility of developing EAF， because the increase of EAF production capacity is always limited by scrapped steel resource in China. Cumulative steel decides the source of the scrapped， while the obstacle for developing EAF is lack of scrapped steel resource. EAF in this research is regarded as an energy efficient way of steelmaking. The substitution among different steelmaking ways is another focus of the research， the adjustment dynamics is investigated.

2. REFERENCE MODE

The time horizon for the model is set at 120 years (from 1980 to 2100). Such a long time period could reflect the predicted whole industrialization period which is one driving force behind energy demand for steel industry， showing how steel industry responds and acts during this transition period.

Steel demand increases significantly with the rapid economic development in China during recent years. It is a driving force behind energy demand. Although the energy price increases as well， the energy cost is somehow offset by the improvement of energy efficiency technology. As a result， the cost increases slowly， which can not prevent the rising trend of energy demand. Secondly， energy demand influences the energy consumption directly， which is closely related to the country’s energy conservation.

The energy expense is directly influenced by the energy price variation and energy consumption (In this particular model， to simplify the model structure， we assume that energy consumption is a delay of energy demand.). The energy demand will eventually decrease responding to the decreasing steel demand after the transition period. However， if the energy price continues to increase and due to low potential for the improvement of energy efficiency in a long run， the expense may not decrease as fast as energy demand. Increase of energy expense does create a financial problem for steel industry， exerting pressure on the production cost of steelmaking.

3. RESEARCH METHODOLOGY

The research is about an energy intensive industry. Such an industry in China is complicated by interrelated nature of the elements. System Dynamics is a computer-aided approach for analyzing and solving complex problems with a focus on policy analysis and design. It is a methodology for studying and managing complex feedback systems. The elements described in the above paragraph have feedbacks among each other; one can not study the link between one factor to the other or in the opposite way independently and predict how the system will behave. Only the study of the whole system as a feedback system will lead to correct results.

4. MAJOR MODEL ASSUMPTIONS

All models are wrong. Models are only valid under certain assumptions. Such assumptions and exclusions can radically reduce the size of the model and help to achieve simplicity and clarity.

Once the problem has been identified and characterized over an appropriate time horizon， a dynamic hypothesis can be formulated accounting for the problematic behavior.

When energy price rises and steel demand increases during the economy transition (modeled as reference steel demand)， high energy expense and energy demand are the direct results from the above causes. Energy price and CO2 emission from energy consumption act as two incentives for the steel industry to develop energy efficiency technology. In addition， increasing steel demand lead to more scrapped steel resource which promotes the development of more energy efficient way of steelmaking， namely EAF. By raising the proportion of EAF， energy efficiency is further improved and CO2 emission problem will be well eased.

5. Policy Development

Policies here are categorized into two kinds: energy efficiency technology development policy and steelmaking process improvement policy.

-ENERGY EFFICIENCY TECHNOLOGY DEVELOPMENT POLICY

With respect to energy tax， the government in China so far has not levied carbon tax， namely the CO2 tax. Besides the carbon tax， the energy tax， which is called resource tax in China， is levied at a low rate compared to its real price. While the government thinks that the current energy price can not reflect its economic value and scarcity of natural resources， pollution tax aiming at reduce CO2 is scheduled to be levied and even higher resource tax rate is going to be raised in the near future.

In the real world， the importance of incentives for the steel industry to develop energy efficiency technology varies in terms of different time period or government policies. If the incentive from energy price increases rather rapidly in the future due to resource scarcity or market supply and demand， policies related to energy tax may become more effective.

-STEELMAKING PROCESS IMPROVEMENT POLICY

Among all three steelmaking process， EAF is regarded as the one that promotes energy conservation and environmental protection. Scrapped steel mainly comes from the recycling of depreciated social capitals; the cycle period is around 18 years in China. Taking the loss and recycling rate of the current level into account， the situation described in the former section will be greatly eased in 10 to 15 years. Besides the gradual increment of depreciated steels， the steel industry can raise another technical factor: the scrapped steel recycling rate. The recycling rate has been kept around 40% in the past 2 decades， while this technical parameter in developed countries is high. This condition indicates China has large potential to raise this technical parameter.

The policy at this stage aims to raise the proportion of EAF among steelmaking process. Raising the recycling rate is the main policy of improving steelmaking process for this particular model. Such a technical improvement needs more attention from the industry， and the government may need to make relevant regulations to help the industry recycle more scrapped steels from social capitals.

6. CONCLUSIONS AND IMPLEMENTATIONS

Energy taxes， based either on carbon content or particular fuels， would allow energy users to trade off the relative merits of paying the penalties versus adopting new kinds of energy or technologies to limit scarce and carbon intensive energy use and avoid carbon emissions.

The effect of energy tax is little both in energy conservation and in limiting CO2 emission in this particular model; on the contrary， the expense is high.

Policies related to subsidy can achieve good results with low expense in this particular model.

Raising EAF proportion is a focus that has been concerned about during recent years due to continuously increasing iron ore price and sustainable development. China has large potential to raise its recycling rate compared to the level of advanced steelmaking countries. The policy may take a long time to see the effect， but it can be developed quickly compared to the energy efficiency technology due to low advancement cost. Thus it is worthwhile and beneficial for the steel industry to invest more on recycling technology and adjust its steelmaking way.

Last but not least， the model is a tool to test policy and scenarios instead of a way of forecasting or predicting the future. Policies here provide new ways of thinking something in “what if” manner for the policymakers to move the system outside the limited range of historical experience. Most of these single polices have their limitations to achieve significant reductions in a cost-effective manner with easy implementation， policymakers need to seek a combination of different policies.