Glass Melting Technology: A Technical and Economic ... - OSTI

development and capital investment for energy reduction. The assumption is that the energy
needed for glass melting will be available in the quantity and form that the technology requires.
Since the energy crisis of the late 1970s, except for brief volatile periods, the United States has
been in a 25-year period of low energy cost escalation. Energy has been readily available during
this period. The value of the energy saved at the current cost of energy with an assumed low rate
of cost escalation is not sufficient to justify many energy-saving technologies, particularly
technologies that require a substantial investment of capital.
An “Annual Energy Outlook,” published by the Energy Information Administration in the US
Department of Energy, projects energy costs for 20 to 25 years in the future. These projections
consider multiple low-growth and high growth economic scenarios. The January 2003
“Outlook,” which projects energy demand, supply, and cost to 2025, forecasts relatively low
energy cost escalation, even for the higher growth and greater energy demand scenario. This
forecast, like any forecast of future events and expectations, may prove to be inaccurate. Glass
industry experts who participated in a national workshop in connection with this study concluded
that if the cost of energy were to increase three to five times over current levels, the glass
industry’s interest in energy-saving technologies would increase dramatically. But without
reliable forecasts for future energy costs, the economic impetus is not present for the aggressive
pursuit of revolutionary, energy-saving technology for glass melting.
Overall, energy consumed for glass melting has been reduced over the last 30 years. This energy
conservation has been achieved by:
• conversion from coal producer gas to high-caloric fuel, or fuel oils and natural gas;
• application of fuse cast AZS refractories instead of low-grade aluminosilicate refractories for
glass containment has allowed higher glass melting temperatures, greater use of insulation, and
longer furnace campaigns between cold repairs
• larger regenerators with improved checker design and structure;
• recycling post-consumer glass; average cullet percentage in the US increased from 15 to 35
percent, and in Europe from 45 to 50 percent;
• production with greater throughput from larger furnaces.
The amount of energy that can be saved in the future is proportionally less today than it was in
past years. For further energy savings, the conservation strategy must be practical. In the last 10
years, the cost of energy did not justify the cost of capital investment required for further
savings. The low cost of available energy has not warranted the investment in development of
technology to save energy.
To justify a furnace capital expenditure of $1 million if the cost of capital were 10 percent, a
container-glass producer would need to save 6.5 percent of the batch and melting energy. If
capital costs were 20 percent, the producer would need to reduce energy costs by nearly 12
percent. The energy cost reduction required to justify capital expenditure varies with cost of
energy. An investment of $1 million requires an annual before-tax savings of $150,000 to earn a
10 percent cost of capital, and a savings of $270,000 to earn a 20 percent cost of capital. These
levels of savings can relate to cost reduction in batch, melting and refining energy costs.
(See Table II.12 for energy reduction required for return on investment.)
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