Energy Futures and Urban Air Pollution Challenges for China and the United States (2008) / Chapter Skim
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7 Renewable Energy Resources
7 Renewable Energy Resources
Pages 207-228
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From page 207... ...
Their benefits are well known: in most cases, they produce little or no pollution emissions and because the resources are renewable, they reduce dependencies on foreign supplies and more importantly on finite resources of any kind. This chapter provides a brief discussion of the candidate renewable sources/technologies that could have an important impact in the medium to long term.
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From page 208... ...
A separate discussion of renewable liquid fuels (biofuels) will follow.
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From page 209... ...
Figure 7-3 shows trends in renewable energy consumed in the United States by sector, 1949-2005, and illustrates that: • Most renewable energy is consumed in the industrial sector, followed by consumption in the residential sector. • Consumption in the transportation sector (alcohol fuels)
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From page 210... ...
In both countries, conventional hydroelectric power is the dominant renewable resource, although the scale of plants differs in many cases. In the United States, most hydroelectric plants are large-scale plants; in Municipal solid waste, landfill gas, sludge waste, tires, agricultural by-products, and other b iomass.
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From page 211... ...
As of 2004, domestic hydropower generation (including small-scale hydropower) capacity was 108,260 MW, with total energy production of 328,000 GWh (15 percent of total production)
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From page 212... ...
SOURCE: China Electric Power Yearbook, 2005.
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From page 213... ...
Wind Wind energy is an electric generation option that has received considerable interest in recent years, and is a well-established proven technology that generates few environmental emissions. Wind is one of the most rapidly growing energy technologies in the United States.
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From page 214... ...
, local industrial capacity, and local political will, the city has increased household solar water heater use to 99 percent in the central urban district, and most traffic signals and outdoor lighting are powered by PV cells. It appears that one key element in Rizhao's reliance on solar power has been the provincial government's support for R&D, which helped improve the technologies and ultimately to lower costs to consumers, while strengthening the local manufacturing capacity (Bai, 2007)
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From page 215... ...
In China, geological surveys suggest that geothermal energy resources are abundant and widely distributed. However, of the estimated 5,800 MW of potential capacity, only 30 MW is currently being exploited (CREIA, 2007)
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From page 216... ...
of biogas was utilized, providing energy to 14 million rural residents. In China, direct burning is the primary use for biomass; much of this takes place in central and western rural China, and its low thermal efficiency (10 Additional infrastructure will be required to assure adequate consumer access to biomass derived liquid fuels.
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From page 217... ...
Thus, a major challenge for China will be capitalizing on its abundant biomass resources by upgrading the conversion technologies used, in order to limit the damages caused to human health and the environment. The government has set a target of 3 GW of biomass
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From page 218... ...
To meet the growing demand for liquid fuels, it is apparent that lignocellulosic forms of biomass will need to supplant the Itshould be noted that there continues to be debate over the issue of net energy gain or loss with the production of liquid fuels from biomass. A recent study suggested that, from a life-cycle energy balance perspective, ethanol derived from corn is only slightly positive; ethanol from sugarcane shows a slightly better net positive balance, but wide-scale use of ethanol as an alternative to petroleum-based liquid fuels will almost certainly require cellulosic technology (Farrell et al., 2006)
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From page 219... ...
Small-scale operations are well distributed, but are not producing fuel ethanol; China's four state-owned large-scale fuel ethanol manufacturers produced 1.02 million tons (340 million gallons) of ethanol using stale grain as a feedstock (Wu et al., 2007)
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From page 220... ...
. Additionally, the Ministry of Science and Technology is funding research on cellulosic conversion, in order to make use of China's abundant cellulosic resources.
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From page 221... ...
The total resource potential is based on an increase of over seven times current biomass production levels. However, the authors believe that the 1.3 billion tons can be produced with relatively modest changes to land use and agricultural and forestry practices. The values in the report should not be thought of as upper limits, but just one scenario for a set of assumptions.
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From page 222... ...
Nevertheless, a realistic technological and economic assessment of the characteristics of these options for generating electricity reveals challenges, as well as the more advertised opportunities. Most major hydroelectric capacity options in the United States have long since been exploited, and proposals for new or expanded hydro facilities often encounter resistance.
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From page 223... ...
Biomass gasification significantly reduces air pollution emissions and provides opportunities to extract high-value chemicals and other by-products, but it is not yet commercial in the United States or in China, and it will face challenges in terms of feedstock uniformity and gas cleanup. The remaining two renewable energy options for large-scale electricity generation are central receiver solar thermal power and utility-scale PV.
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From page 224... ...
However, Figure 7-9 projects that levelized costs would stay above avoided costs for other sources of power generation through 2015 (aside from limited areas with geothermal resources) , and that solar thermal generation may still be prohibitively costly in 2030 (EIA, 2007)
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From page 225... ...
There is a reverse distribution of the most promising renewable energy resources, relative to population. This is beneficial for remote areas in early stages of urbanization, for they have an opportunity to meet their rapidly increasing energy needs with clean renewable sources.
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From page 226... ...
DOE's National Energy and Technology Laboratory. Hydrogen as a fuel source is appealing because it holds the potential to replace gasoline in the transportation sector, exclusively using domestic resources, thereby significantly reducing dependence on foreign oil.
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From page 227... ...
First, it must prove to be cost-effective. Hydrogen is currently produced at reasonable cost for industrial purposes, but large-scale use would require production using renewable energy, which is still often prohibitively costly.
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From page 228... ...
2002. An economic analysis of biomass gasification and power generation in China.
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