Cogeneration and On-site Power Production

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Investing in distributed energy in China

The Global Environment Facility is the world’s largest public fund to protect the global environment. On-site renewables and cogeneration have been one of its main focuses in recent years – here, the GEF’s Dimistrios Zevgolis, Dr Robert K Dixon and Dr Zhihong Zhang describe projects to encourage power generation based on recovered waste heat in two large industrial sectors in China.

As the financial mechanism of the United Nations Framework Convention on Climate Change (UNFCCC), the Global Environment Facility (GEF) works towards reducing and avoiding greenhouse gas emissions through investing mainly into renewable energy, and energy efficiency practices in developing countries and emerging economies. The GEF supports the transformation of energy markets in developing countries by creating enabling policy and regulatory frameworks, designing innovative financial instruments, building local capacities, and transferring knowledge.

The GEF’s work has been substantial not only in the field of market transformation, but also in paving the way for the deployment and diffusion of innovative, environmentally sound technologies. For example, in developing countries such as Egypt, Mexico and Morocco GEF has pioneered concentrating solar power technologies, as well as bringing distributed PV technology to Africa, biomass gasification and cogeneration to Asia, and fuel cell buses powered buses to China and Brazil.

By 2009, the GEF had invested $2.7 billion to support climate change mitigation projects in developing countries and economies in transition, and has leveraged another $17.2 billion in co-financing. More than 1 billion tonnes of greenhouse gas emissions, an amount equivalent to nearly 5% of annual human emissions, have been avoided with GEF support.

On-site renewable energy production and cogeneration of heat and power, has been the main focus of the renewable energy and energy efficiency portfolio of the GEF during the last 19 years. The GEF has invested more than $390 million, leveraged by $2.3 billion, in 79 projects that achieve on-site power generation or cogeneration of heat and power, mainly through the use of biomass resources (landfill gas, agricultural and municipal waste, and forest residues), waste heat recovery, and the use of solar energy. Some of these investments are quite innovative, such as the promotion of solar concentrator based process heat applications in India, the biomass integrated gasification/gas turbine project in Brazil, or the application of microturbine cogeneration in Indonesia.

DISTRIBUTED ENERGY IN CHINA

China is the single largest partner of the GEF with an impressive track record of projects. During the past 19 years, the GEF has invested $450 million for mitigation activities in China, leveraged by $4.08 million. More than $100 million out of this GEF funding has been directed to investments in distributed energy, such as on-site power production and cogeneration in the industrial sector. The agricultural sector is another partner of the GEF in China, with several projects in the field of distributed power and heat production from biomass resources.

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With GEF support, Shenhe Cement Company in Zhejang constructd this fuel free power plant in China using waste heat from rotary clinker kilns.

POWER FROM RESIDUAL HEAT AT CEMENT PLANTS

Cement manufacture causes significant environmental impacts at all stages of the process. In particular, these include the need for large energy inputs (in China primarily from coal) during cement manufacture, and the release of dust from mining and cement plant operations (the dust production depends on the degree of clean-up provided). Cement manufacture contributes about 5% of global anthropogenic carbon dioxide emissions. Cement is primarily manufactured from limestone to produce clinker which is then ground and mixed with other materials to give Portland or other types of cement.

China accounts for nearly 50% of world cement production and demand. In 2003, there were 4700 cement plants in China, primarily serving local markets, although this number is shrinking as smaller plants are closed. In 2003, more than 83% came from small producers that average less than 150,000 tonnes annually, compared with the world average of 600,000 tonnes a year per producer. These small producers use small output mechanical shaft kilns which have a high energy use per output, whereas more than 90% of output in developed countries is produced by larger capacity modern rotary kilns.

When the project was being implemented, 5-stage pre-heater ‘new dry process’ kilns were being developed and introduced in China as it caught up with world best practice in the design of NDP rotary kilns. Such 5-stage pre-heater NDP kilns give a lower pre-heater exit temperature for waste heat recovery (WHR), and hence are more efficient in terms of cement production, but need to use improved WHR technology compared to the older 4-stage cyclone pre-heater kilns that were the previously highest technological level cement kilns used in China.

The project’s pilot demonstration – Zhejiang Shenhe Cement Co’s 5-stage cyclone pre-heater WHR and power generation plant, recovers waste heat from the kiln outlet cooler and inlet pre-heater through a waste heat boiler, and uses a steam turbine to generate electricity from the otherwise rejected waste heat, with no added fuel being used. The Shenhe WHR and power generation plant was designed by the Tianjin Cement Industry Design and Research Institute, and was the first in China to use a 5-stage cyclone pre-heater at its time of introduction.

The first generation cement WHR power generation unit designed in 2004 and as used at Shenhe on its 2500 tpd NDP line achieved 26 to 28 kWh per tonne of clinker, and saved nearly 20,000 tonnes of CO2 per year by replacing electricity from coal fired power plants. The third generation cement 5-stage cyclone pre-heater with WHR plant, designed by the Tianjin Cement Industry Design and Research Institute was installed at the Shenhe 1000 tpd NDP line produces 35 to 38 kWh per tonne of clinker.

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With GEF support, Xinggao Coking Group in Shanxi has successfully demonstrated the state-of-the-art clean coking technology in China, while recovering waste heat from the coke ovens for power generation.

For the cement industry, the successful pilot of power generation utilizing residual heat from the new rotary kiln process facilitated the promotion of this technique in China. A preferential policy to this effect has been issued in Zhejiang Province, and seems to be effectively applied as well. Under national policy the technology is in principle mandatory in new NDP kilns of over 2000 tpd. Furthermore, in the medium and long-term National Conservation Plan issued by NDRC in December 2004, this technology is now on the list of encouraged techniques.

WASTE HEAT RECOVERY AT COKING PLANTS

Traditionally, coking plants are large and heavily polluting industrial plants that are either stand-alone or integrated with steel works. China is a major coke producer and exporter. The project supported the Gaoping Xinggao pilot coking plant in Shanxi Province as a pilot demonstration project. This plant has demonstrated the successful use in China of the new clean-type coking technology with heat recovery being used for electricity power production (the clean-coking technology was apparently first demonstrated in the US in 1997).

Partly due to the successful pilot project, the innovative ‘Clean Type’ coking oven technique has been listed in a national programme for industrial sector technology improvement. The government of Shanxi province (the dominant coke producing province in China) is promoting both this type of oven and residual heat power generation.

In contrast to mechanical plants, the clean-type technology plants running at negative pressure use less coal to produce the same quantity of coke, and produce essentially no local pollution. The clean-type technology burns up the coal liquids and gases, and can then use the resulting hot coking oven exhaust gas to generate electricity. The clean-type technology also supports the use of flue gas clean-up equipment that can remove nearly all of the dust, ash, and eliminate the sulphur emissions that are normally associated with coke production.

Also, the project demonstrates the waste heat power generation through a 15 MW condensing steam turbine with an entry temperature of 420°C. The coking oven waste gas is at a temperature of 850-1050°C, depending on coking oven output levels. This is compatible with modern steam turbines which can operate at over 550°C turbine entry temperature. The power plant can generate 120 million kWh annually, which is equivalent to recovering 92,000 tonnes of coal, or reducing CO2 emissions by 229,000 tonnes. The coking plant achieved a nearly 20% improvement in power output per level of coking production over its initial design, from a range of heat recovery process refinements.

The Xinggao plant was designated by the State Economic and Trade Commission (now incorporated in NDRC) as a key national technical renovation project. The ‘clean-type’ coking oven and waste heat power generation technology has been listed by the Shanxi (the main coke producing province in China) government as the key encouraged technology in the coking industry.

The Gaoping Xinggao coking pilot plant has successfully demonstrated (in technical and financial terms) heat recovery power generation for clean-type coking plants in China. In addition, the Xinggao coking pilot plant has no visible pollution from any aspect of its operation when one visits its site. This is because, in addition to the lack of coking oven pollution, the waste heat recovery facilitates the use of desulphurization and ash removal from the coking oven waste gases when they are just discharged at high temperature, as is the normal situation with clean-type coking ovens without waste heat recovery.

The Gaoping Xinggao clean coking plant has provided commercial training for personnel from coking plants in China and India. There has also been considerable publicity generated by this pilot, and Xinggao clearly has worked hard at generating publicity and providing training on the technology that they have successfully demonstrated. The Xinggao Clean Coking pilot has attracted considerable international attention, with hosted visits for Australian, German, Iranian, Japanese, Ukrainian, and US coking experts. This publicity and commercial training seems to have been the single most important factor behind the large and highly significant self-replication potential of this clean-type coking technology.

With GEF support, Xinggao Coking Group in Shanxi has successfully demonstrated the state-of-the-art clean coking technology in China, while recovering waste heat from the coke ovens for power generation.

CONCLUSIONS

The impressive record of the GEFs investments, not only in China but also in the rest of the developing countries and emerging economies, demonstrates that distributed energy is the most efficient and effective option to achieve sustainable development. The GEF will continue supporting distributed energy technologies that are commercially available but face barriers and require market pull to achieve widespread adoption and diffusion. In parallel, the GEF will keep focusing on innovative, emerging low-carbon technologies at the stage of market demonstration or commercialization where technology push is still critical.

Dimistrios Zevgolis, Dr Robert K Dixon and Dr Zhihong Zhang are all with the Global Environment Facility, Washington DC, US: Dimistrios Zevgolis as Program Manager and Climate Specialist, Dr Robert K Dixon as Climate Change Team Leader and Dr Zhihong Zhang as Climate Change Mitigation Cluster Coordinator.
Email:
dzevgolis@thegef.org  Web: www.thegef.org

 


 

Case study: Waste heat recovery at cement and coking plants in China

During the last decade, GEF invested in a project for the adoption of energy efficiency measures and waste heat recovery technologies in brick, cement, metal casting and coking plants in China.

These four sectors account for one-sixth of China’s carbon dioxide emissions. The project was implemented by the United Nations Development Programme (UNDP) between 2001 and 2007, and jointly executed by the United Nations Industrial Development Organization UNIDO and the Ministry of Agriculture.

The project planned a wide and deep involvement of stakeholders, who came from relevant state and local governments, industry associations, financing organizations, research institutes, universities, private sector enterprises, NGOs, and international organizations and institutions.

The use of the PIC and LPICs – national and local Policy Implementation Committees – was a particularly relevant project design element – in particular in China’s current stage of social market development. The use of formal cooperation Voluntary Agreements (VAs) between the project, local government agencies (through the LPICs), relevant industry associations and pilot and formal replication sites proved to be very effective in China.

In the eight pilot-demonstration projects implemented, greenhouse gas savings of 193,000 tonnes CO2/yr have been achieved compared with the 85,000 tonne/yr CO2 savings anticipated in the project’s design. In addition, 111 formal replication projects achieved carbon dioxide reductions of 1.3 million tonnes/yr.


 

The GEF

The Global Environment Facility (GEF) unites 181 member governments, in a unique partnership with international institutions, non-governmental organizations, and the private sector, to address global environmental issues. The GEF provides financial and technical assistance to developing countries and countries with economies in transition for projects related to climate change, biodiversity, international waters, land degradation, the ozone layer, and persistent organic pollutants. These projects benefit the global environment, linking local, national, and global environmental challenges and promoting sustainable livelihoods.

The GEF has allocated $8.8 billion, supplemented by more than $38.7 billion in co-financing, for more than 2400 projects in more than 165 developing countries and countries with economies in transition.

The GEF also serves as financial mechanism for the following conventions:

  • United Nations Framework Convention on Climate Change (UNFCCC)
  • Convention on Biological Diversity (CBD)
  • Stockholm Convention on Persistent Organic Pollutants (POPs)
  • UN Convention to Combat Desertification (UNCCD)
  • The GEF, although not linked formally to the Montreal Protocol on Substances That Deplete the Ozone Layer (MP), supports implementation of the Protocol in countries with economies in transition.

Working through a network of 10 different agencies that implement its projects allows the GEF to stimulate constructive competition, and select the best and most cost-effective initiatives from a larger pool. These 10 GEF agencies are: the UN Development Programme; the UN Environment Programme; the World Bank; the UN Food and Agriculture Organization; the UN Industrial Development Organization; the African Development Bank; the Asian Development Bank; the European Bank for Reconstruction and Development; the Inter-American Development Bank; and the International Fund for Agricultural Development. nstruction and Development; the Inter-American Development Bank; and the International Fund for Agricultural Development.

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