MANY ALTERNATIVES FOR CO2 CUTS, SAYS IPCC PANEL

Substantial cuts in global emissions of carbon dioxide (CO2), the leading greenhouse gas implicated in climate change, can be achieved over the next 30 years through a variety of technology and policy options at little or no increase in cost over business as usual, according to Working Group II of the Intergovernmental Panel on Climate Change (IPCC).

In its new “Summary for Policymakers,” released in November, the panel examines several alternatives for world energy supply through the year 2100. All options reviewed envision very large growth in energy from “intermittent renewables” (wind and solar) over the next century.

Global energy use is a major contributor to the increase of greenhouse gases in the atmosphere. According to the report, 385 EJ exajoules; one exajoule is equal to 45 million tons of coal or 170 million barrels of oil of energy were consumed worldwide in 1990, resulting in the release of six billion tons of carbon 22 billion tons of carbon dioxide into the atmosphere. Added the report, “Future energy demand is anticipated to continue to grow, at least through the first half of the next century. The IPCC . . . projects that without policy intervention, there could be significant growth in emissions from the industrial, transportation, and commercial/residential buildings sectors.”

In 1992, the IPCC developed six energy scenarios based on different supply assumptions. All but one (a case with very low population and economic growth) showed substantial increases in CO2 emissions, from 22 billion tons in 1990 to a range of 36 billion tons to 128 billion tons per year in 2100.

Working Group II, however, found that emissions could be restrained well below all of the 1992 IPCC projections, even with high future energy demand. It developed five new scenarios of a Low CO2-Emitting Energy Supply System (LESS), which it said are “‘thought experiments’ exploring possible global energy systems.”

In the LESS scenarios, world population grows from 5.3 billion in 1990 to 10.5 billion by 2100. Economic growth, in terms of gross domestic product (GDP), jumps to 25 times 1990 levels by 2100, with 13-fold increases in industrialized countries and 70-fold increases in developing countries. Heavy use is made of energy efficiency measures in all scenarios. According to the working group, “Analysis of these variants leads to the following conclusions:

o “Deep reductions of CO2 emissions from energy supply systems are technically possible within 50 to 100 years, using alternative strategies.

o “Many combinations of the options identified in this assessment could reduce global CO2 emissions from fossil fuels from about 22 billion tons to about 15 billion tons by 2050, and to about seven billion tons by 2100.

o “Higher energy efficiency is underscored for achieving deep reductions in CO2 emissions, for increasing the flexibility of supply side combinations, and for reducing overall energy system costs. . .”

Added the report, ” . . . Within the wide range of future energy prices, one or more of the scenarios would plausibly be capable of providing the demanded energy services at estimated costs that are approximately the same as estimated future costs for current conventional energy.”

The report spoke in positive terms of renewable energy sources, noting in part, “Solar, biomass, wind, hydro, and geothermal technologies already are widely used. In 1990, renewable sources of energy contributed about 20% of the world’s primary energy consumption, most of it fuelwood and hydropower.

“Technological advances offer new opportunities and declining costs for energy from these sources. In the longer term, renewable sources of energy could meet a major part of the world’s demand for energy. Power systems can easily accommodate limited fractions of intermittent generation, and with the addition of fast-responding backup and storage units, also higher fractions.”

Each of the LESS scenarios sees substantial growth in intermittent renewables. By the year 2025, in the nuclear- intensive LESS forecast–the worst of the five for intermittent renewables–wind and solar would deliver 34.8 EJ (about 3.2 trillion kWh annually, or more electric power than the U.S. uses today), worldwide, and by the year 2100, 103.9 EJ (9.5 trillion kWh). In the biomass-intensive, gas-intensive, and coal- intensive scenarios, intermittent renewables are projected to deliver 37.1 EJ (3.4 trillion kWh) annually by 2025 and 163.2 EJ (15 trillion kWh) by 2100. And in the high-demand LESS scenario, intermittents deliver 37.1 EJ in 2025 and 318.3 EJ (29 trillion kWh) in 2100.

Continues the report, “The literature provides strong support for the feasibility of achieving the performance and cost characteristics assumed for energy technologies in the LESS constructions, within the next two decades, though it is impossible to be certain until the research and development is complete and the technologies have been tested in the market.

“Moreover, these performance and cost characteristics cannot be achieved without a strong and sustained investment in research, development, and demonstration (RD&D). Many of the technologies being developed would need initial support to enter the market, and to reach sufficient volume to lower costs to become competitive.”

“Second Assessment Report, Summary for Policymakers: Impacts, Adaptations and Mitigation Options” is available from IPCC Working Group II Technical Support Unit, 300 D Street, SW, Suite 840, Washington, DC 20024, USA, phone (202) 651-8260, fax (202) 554-6858, e-mail <ipcc@usgcrp.gov>.

(The preceding is from the electronic edition of WIND ENERGY WEEKLY, Vol. 14, #678, 25 December 1995, published by the American Wind Energy Association.)