Assessment of biomass for electricity generation in China

Guangling Zhao, Per Christensen, Søren Løkke

Aalborg University, Denmark

In December 2009, China’s State Council announced that the country will cut its carbon emissions by 40-45% from 2005 levels by 2020. The increasing concentrations of greenhouse gases in the atmosphere are gradually affecting the climate. The main contributors to the global climate change issue are CO2 emissions from the combustion of fossil fuels. Biomass, as the substitution of fossil fuel, can significantly contribute to reducing CO2 emissions and mitigating climate change.

The object of this paper is to identify the potential supply of biomass for energy and to assess the impact of power generation from biomass in China.

China is a big agriculture country which has large quantities of biomass energy in the rural area. In this paper, biomass source for power generation includes are agricultural crop and process residues (bagasse and so on), forest wood, organic waste and livestock waste. There were 748.16 Million tons agricultural residues, total forest residues amount to 104748.6 thousand tons and total animal manure energy was 922286.5 thousand tons in 2007. Biomass energy has the potential to replace 10% of the primary energy consumption all over the country.

This paper employed life cycle assessment method to address the impact of electricity generation from biomass in China. Life cycle assessment investigates the environmental impacts throughout the full life cycle of biomass. In the assessment, it considered not only four biomass sources but also three primary technology categories used for combustion which are direct combustion of biomass, biomass gasification and waste incineration. Scenarios are made based on the biomass sources and technologies. The aim of this part is to provide information of emissions during which stage of the life cycle of biomass.

Development and application of a LCA model for coal conversion products (Coal to Y)

Christian Nissing, Loïc Coënt, Nathalie Girault

TOTAL Gas & Power, France

TOTAL Gas & Power launched a series of development studies in order to investigate the potentials for coal conversion projects (Coal to Y) for the production of fuels and primary products for the petrochemical industry. A crucial role is played by the aspects of Carbon Capture and Storage (CCS).

Based on these studies, a methodology and a model for life cycle analysis (LCA) were developed in order to understand the environmental impacts associated with Coal to Y conversion routes, especially regarding GHG emissions and energy efficiency. The model was designed around the need for adaptability to a) the geographic location of the coal mine and the coal conversion plant, and b) the final products and their respective markets in the fuel and petrochemical sectors.

By applying the model to a potential Coal to Methanol application by utilising original data and in-house expertise, first results were generated, giving valuable insights especially into the critical elements of the CO2 management system. Results showed that the developed LCA model is a powerfull tool that can give guidance in the development of future Clean Coal projects.

Life cycle assessment of a solar PV/T concentrator system

Maurizio Cellura¹, Vito Grippaldi², Valerio Lo Brano¹, Sonia Longo¹, Marina Mistretta²

¹Università di Palermo, Italy; ²Università di Reggio Calabria, Italy

Technological advances in the field of renewable energy systems and the requirement of climate change mitigation have developed an increasing attention on innovative energy technologies. In particular a growing interest has risen for the hybrid Photovoltaic/Thermal (PV/T) solar systems, in which typically photovoltaic cells (PV) are integrated with the solar thermal collectors (T) to provide simultaneous production of thermal and electrical energy from solar radiation. An internal refrigeration system allows to control the cell temperature and to transfer the heat to air or water employed for several application (air conditioning, warm water demand, industrial processes). A significant solution to maximize the solar inputs is given by the concentration of solar radiation by means of mirrors and reflecting surfaces. A parabolic reflecting system concentrates the solar radiation to a narrow surface covered by PV cells, increasing their outputs. The higher temperature of the collectors allows to reach higher temperatures of the thermal fluid. That allows to reduce the employed surface of PV cells that in the photovoltaic technology involves the highest energy and environmental impacts.

In this paper the authors will present the energy and environmental analysis of a hybrid solar concentration system characterized by five interconnected parabolic PV/T modules, installed on the DREAM building in Palermo (Italy).

The analysis is carried out by means of Life Cycle Assessment (LCA) methodology, in order to assess the whole life-cycle of the energy conversion plant, including the production process, the transport of materials, the installation and the operation phases. Data survey from the producing company concerns the consumption of energy sources and raw materials. Impacts related to the end-life of the plant are estimated on the basis of future possible disposal and recycling scenarios.

The results will allow to identify the steps and the system components which are responsible of the highest environmental impacts. The assessment of the energy and environmental benefits and drawbacks related to PV/T plant, in comparison with traditional devices, will be carried out accounting for the energy and CO2eq payback indices. These indices represent the time period needed for the benefits got in the use phase to equal the life-cycle energy consumption and CO2eq emissions of the whole system.

The results showed in the paper derive from the framework of the Italian Project PRIN 2008 ‘‘Definition of innovative criteria for the environmental oriented design and production of Energy Using Products in the civil sector”.

Energy efficiency and renewable energy in need of life cycle management: The cases of compact fluorescents and solar water heaters

Harro von Blottnitz

University of Cape Town, South Africa

Energy efficiency interventions and renewable energy installations might be viewed as being inherently green and therefore not in need of further life cycle assessment and management interventions.That is not necessarily so, as illustrated by the cases of compact fluorescent lightbulbs (CLFs) and solar water heaters (SWH), both in the South African context.

CFLs were first introduced in large quantities into the South African market in response to an electricity crisis in Cape Town in 2007, when an accident at the country's only nuclear power station resulted in several months of supply shortages. 5 million bulbs were distributed for free within just a few months. Only after the crisis was a programme established to develop an end-of-life infrastructure equipped to deal with the mercury toxicity threat. Four years later, with CFLs now the mainstream household lighting choice, consumers are still in the dark about the appropriate management of their broken bulbs. At the same time, with electricity shortages again looming, more than 40 million bulbs have again been distributed nationwide.

Solar water heaters have recently been recognised as a cost effective electricity-saving renewable energy option for installation by homeowners and housing project developers. The state-owned South African electricity supply company has set a target of 250000 installations and is offering subsidies, but less than 3000 requests were received in 2010. A life cycle analysis for this technology deployed in Cape Town conditions indicates energy and carbon payback times of less than 6 months. Financial payback, on the other hand, is still in the 5-10 year range. The implication is that increasing the collector area would make immediate sense from a GHG emission reductions perspective, but not necessarily from a financial position. Solar water heating rollout programs should thus be reinspected, and measures introduced to convince installers to optimise collector areas, possibly by harnessing additional carbon finance.

It may be concluded that LCA can identify and quantify both new environmental risks and additional environmental opportunities associated with "green technologies", but that management interventions need to be planned and executed to mitigate such risks and harness such opportunities.

Analysis on correlation relationship between life cycle greenhouse gas emission and life cycle cost of electricity generation system for energy resources

Heetae Kim, Tae Kyu Ahn

Sungkyunkwan University, South Korea

In this work, we analyzed correlations between life-cycle greenhouse gas (GHG) emissions and life-cycle cost of energy resources. Energy resources studied in this paper include coal, natural gas, nuclear power, hydropower, geothermal energy, wind power, solar thermal energy, and solar photovoltaic energy, and all of them are used to generate electricity. We calculated the mean values, ranges of maximum minus minimum values, and ranges of 90% confidence interval of life-cycle GHG emissions and life-cycle cost of each energy resource. Based on the values, we plotted them in two dimensional graphs to analyze a relationship and characteristics between GHG emissions and cost. Besides, to analyze the technical maturity, the GHG emissions and the range of minimum and maximum values were compared to each other. For the electric generation, energy resources are largely inverse proportional to the GHG emission and the corresponding cost.