Elsevier

Energy

Volume 36, Issue 9, September 2011, Pages 5640-5648
Energy

Metal requirements of low-carbon power generation

https://doi.org/10.1016/j.energy.2011.07.003Get rights and content

Abstract

Today, almost 70% of the electricity is produced from fossil fuels and power generation accounts for over 40% of global CO2 emissions. If the targets to reduce climate change are to be met, substantial reductions in emissions are necessary. Compared to other sectors emission reductions in the power sector are relatively easy to achieve because it consists mainly of point-sources. Carbon Capture and Storage (CCS) and the use of low-carbon alternative energy sources are the two categories of options to reduce CO2 emissions. However, for both options additional infrastructure and equipment is needed. This article compares CO2 emissions and metal requirements of different low-carbon power generation technologies on the basis of Life Cycle Assessment. We analyze the most critical output (CO2) and the most critical input (metals) in the same methodological framework. CO2 emissions and metal requirements are compared with annual global emissions and annual production for different metals. It was found that all technologies are very effective in reducing CO2 emissions. However, CCS and especially non-fossil technologies are substantially more metal intensive than existing power generation. A transition to a low-carbon based power generation would require a substantial upscaling of current mining of several metals.

Highlights

► We analyze CO2 emissions and metal requirements of low-carbon power through LCA. ► CCS and renewables both substantially reduce CO2 emissions from power generation. ► Both require substantially more metals than the current mix. ► Transition to a low-carbon power generation requires a substantial upscaling of current mining.

Introduction

The demand for electricity has been rising steadily ever since its introduction in the late 19th century [1]. Since 1980 the average annual growth in demand has been over 3% and this growth is projected to continue in the future [2]. The expected introduction of new technologies such as electric vehicles and heat pumps may even accelerate this demand growth in the future. In 2007 the installed capacity for power generation was over 4000 GW and the world electricity production in that year was almost 20,000 TWh [2]. Almost 70% of this electricity is produced from fossil fuels [3] mainly coal (41%) and natural gas (21%). Power generation accounts for over 40% of global CO2 emissions with an annual emission of 29 Gt in 2007 [4]. Hence, power generation is one of the major contributors to climate change.

If the targets to reduce climate change are to be met, the share of electricity in the energy sector should increase while the emissions from this sector should be substantially reduced. According to the IPCC, emissions need to be reduced by 50–85% below 2000 levels by 2050, in order to stabilize atmospheric CO2 concentrations at 450–490 ppm [5]. This is estimated to correspond with a temperature increase of 2–2.4 °C. More than half of this decrease can be achieved by efficiency improvements, the remainder would have to come from Carbon Capture and Storage (CCS) and non-fossil alternatives [2].

In this paper we explore how and to what extent material requirements may constrain the scale up of low-carbon power generation technologies. In an earlier study we found that for some specific technologies the use of minor metals may prevent them from growing to a significant global scale [6]. The requirements of minor metals will not be discussed here. Next to these minor metals it is also clear that in general the material intensity of new energy technologies is higher than for existing technologies. For CCS this is a logical consequence of the additional infrastructure that is needed for the capture, transport and storage of CO2 in combination with the loss of efficiency in power plants. For non-fossil technologies this is related to the relatively high material intensity that is needed for harvesting energy from diffuse sources, such as wind and sunlight.

In this article we will present an analysis of the effectiveness of CO2 emission reduction and the requirements of selected metals in low-carbon electricity technologies: iron, aluminum, nickel, copper, zinc, tin, molybdenum, silver and uranium. These metals are chosen as a mix of major metals that are important for the general infrastructure: iron, aluminum, copper and zinc; metals that are important for special alloys: nickel, tin and molybdenum; and metals that are important for specific technologies: silver and uranium.

The main research questions addressed here are:

  • 1.

    to what extent can CCS and current non-fossil technologies contribute to CO2 emission reduction targets of 50–85%?

  • 2.

    what are the metal requirements of these CCS and non-fossil technologies?

  • 3.

    how does this metal demand compare to current mine production?

We will start by comparing CO2 emissions and metal requirements of different electricity producing technologies on a life cycle basis. After that CO2 emissions and metal requirements of four cases will be compared:

  • the current electricity mix [3]

  • the current electricity mix but with the assumption that all fossil fuel based electricity would be fitted with CCS

  • an electricity mix consisting of only existing non-fossil technologies

  • the 2050 electricity mix as described in the IEA Blue Map Scenario [7].

The emissions and metal requirements are then compared with annual global CO2 emissions and annual mine production for different metals. Possible bottlenecks are identified and possible solutions are discussed.

Material availability is only one of several factors that might constrain the scale up of the low-carbon electricity technologies. Although these are not the subject of this paper, the most important constraints are briefly discussed in this section: economic constraints, constraints of industrial capacity and spatial and infrastructure planning.

Under the existing economic regime, low-carbon electricity technologies are often more expensive than the dominant fossil fuel based technologies. Only large scale hydropower, nuclear power and wind turbines can compete with fossil fuel based electricity under specific circumstances, while the production price solar electricity is much higher per kWh produced [8], [9]. Furthermore, massive investments are needed for additional infrastructure, either in power transmission for non-fossil energy sources or in CO2 pipelines for the CCS [10]. Subsidies, feed-in-tariffs and other economic instruments are used to overcome this price-gap but this requires considerable shifts in tax regimes and legislation.

However, even if new technologies are competitive with the existing ones, it takes time to build the human and industrial capacity to scale them up to substantial levels i.e. more than 10% of current production [11]. In 2007 world installed power generation capacity was around 4500 GW and this is projected to increase to around 7800 GW by 2030 [2]. Around 37.5 GW newly installed wind capacity was added in 2009 [12]. With a capacity factor of around 0.25–0.4 [13] this is equivalent to about 15 GW installed coal or nuclear capacity (assuming capacity factors of between 0.7 and 0.9) [14]. PV solar is still far from this level with a newly installed capacity of 5.4 GW in 2008 [15]. With a capacity factor of around 0.14 [16] this is equivalent to 1.5 GW installed coal or nuclear power. In order to contribute significantly to the global power generation capacity in 2030 the production of both wind and PV solar need to be scaled up dramatically.

Next to the economic issues and industrial capacity, discussions on spatial and infrastructure planning are common when new nuclear power plants, wind turbines and CCS projects are planned and this can slow down the implementation of these technologies considerably [17], [18].

Section snippets

Analysis of CO2 emissions and metal requirements of different technologies

Life Cycle Assessment (LCA) is used here to analyze the CO2 emissions and metal requirements of different technologies for power generation. In an LCA all emissions and extractions over the whole life cycle of products and services are considered. In this article we limit the scope to CO2 emissions and the metal requirements. Furthermore, we limit the study to the production of the electricity. This means that the transmission, distribution and use of the electricity are not included. This

Implications for mass deployment – three cases

In order to assess the effectiveness with regard to CO2 emission reduction and the metal requirements, three cases for world electricity supply will be compared with a reference case (Table 1). The reference case is based on the 2007 energy mix for power generation as given by the IEA [3]. We defined two alternative cases based on different technologies to reduce global CO2 emissions: CCS and non-fossil energy sources. The cases are not meant to represent a realistic future electricity mix but

Methods & data sources

LCA is used to calculate CO2 emissions and metal requirements per kWh electricity produced with different technologies. The LCA was performed using version 5.0 of CMLCA [23]. EcoInvent 2.0 (Frischknecht et al., 2007) was used as the LCA database for all electricity technologies and all background data and it was supplemented with additional data for Carbon Capture and Storage [24]. Abbreviations, descriptions and data sources of the different technologies are given in Table 2. The basic data

Analysis of the CO2 emissions and metal requirements of individual technologies

The results of the calculations of CO2 emissions and metal requirements of the different electricity producing technologies are given in Fig. 1, Fig. 2, Fig. 3. Fig. 1 shows the CO2 emissions of different technologies. The application of CCS, will reduce CO2 emissions from fossil fuel based power plants with a factor 10. For biomass the emissions related to the use of rape seed oil are about half of those of natural gas fired power, without CCS. For the CHP with waste wood the emissions are a

Conclusions and discussion

About 40% of global CO2 emissions originates from the production of power. In this paper, we have analyzed to what extent these emissions can be reduced, by the use of low-carbon technologies (CCS, nuclear and renewables) and what the consequences would be with regard to the metal requirements. All three electricity mixes presented here (CCS, non-fossil and IEA BLUE Maps) result in a reduction of about 80–90% of CO2 emissions, if comparable reductions would be achieved in other sectors the

Role of funding source

This study has partly been funded by a research grant from Shell. Shell has provided some of the information on CCS technologies. This data has been combined with data on CCS from literature. One of the co-authors, Gert Jan Kramer, is a Shell employee, next to his affiliation as a full professor at the faculty of Science at Leiden University.

References (43)

  • World energy outlook 2009

    (2009)
  • IEA statistics online

    (2009)
  • CO2 emission from fuel combustion

    (2009)
  • B. Metz et al.

    Technical summary

  • R. Kleijn et al.

    Resource constraints in a hydrogen economy based on renewable energy sources

    Renewable and Sustainable Energy Reviews

    (2010)
  • Energy technology perspectives

    (2008)
  • D.M. Kammen et al.

    Assessing the costs of electricity

    Annual Review of Environment and Resources

    (2004)
  • G.J. Kramer et al.

    No quick switch to low-carbon energy

    Nature

    (2009)
  • Global wind power boom continues despite economic woes

    (2009)
  • Large scale integration of wind energy into electricity grids

    (2010)
  • Electric power industry 2008: year in review

    (2010)
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