Future energy sources

A lot of attention in Canada has been focused recently on the Kyoto Agreement to limit the emission of greenhouse gases. But scientifically, the goal for preventing possibly catastrophic global warming has been set far higher than Kyoto’s modest reductions.

An article in the November 1 issue of Science sets out the challenges. Entitled “Advanced Technology Paths to Global Climate Stability: Energy for a Greenhouse Planet,” it was written by a team of 18 scientists and engineers from major universities (including McGill), U.S. government laboratories and agencies, and even Exxon Mobil. The U.S. Department of Energy funded the project.

The level of carbon dioxide in the atmosphere has increased from 275 to 370 parts per million in the past century. Unchecked, it will pass 550 parts per million this century. Climate models and the study of past climate changes indicate that that could warm Earth’s climate as much as it cooled during the last Ice Age. Stabilizing the level of CO2 lower than that will require “Herculean efforts,” the authors conclude.

The world today requires 12 terawatts (12 trillion watts) of power generating capacity, of which 85 percent is fossil-fueled. Power requirements continue to soar as the world’s economy continues to grow. Stabilizing the level of CO2 in the atmosphere by mid-century while permitting the current level of economic growth will require 30 terawatts of carbon-free power production, the study estimates–and we don’t have the technology to achieve that.

Possible sources of carbon-free power include hydrogen, biomass, solar thermal and photovoltaic, wind, hydropower, ocean thermal, geothermal and tidal.

Hydrogen sounds good, but doesn’t exist in geological reservoirs, which means it is usually extracted from hydrocarbons–and per unit of heat generated, more CO2 is produced by making hydrogen from fossil fuel than by burning the fossil fuel directly.

The other sources mentioned currently provide less than one percent of the world’s power, and all suffer from the same problem: low power production per area. For example, producing 10 terawatts of energy using biomass would require more than 10 percent of the Earth’s surface, roughly equivalent to the area covered by all of human agriculture, and a solar array that could produce 10 terawatts would cover a square 470 kilometres on a side. (All the photovoltaic cells shipped from 1982 to 1998 would cover a square only three kilometers on a side.)

Even if we could scale up solar arrays and windmill farms to meet our needs, existing power grids, designed for centralized power plants, couldn’t manage the loads. So another challenge we face this century may be the complete reengineering of our electrical distribution systems.

Another way to harness solar energy is the space solar power satellite, a huge solar array in space that transmits power to Earth by microwave. But getting 10 terawatts of power to Earth by this method would require 660 orbiting solar arrays, each the size of the island of Manhattan. Launch costs, note the study’s authors with admirable understatement, are likely to be “high.”

What about nuclear power? Well, fission, our current method of nuclear energy generation, not only creates radioactive waste and lends itself to the proliferation of nuclear weapons, it’s based on a non-renewable resource, uranium. Meeting the mid-century power needs using fission, the study’s authors estimate, would use up the world’s known reserves in just six to 30 years.

The best hope for a long-term energy solution remains fusion. Fission releases energy through by splitting a large atom (that of uranium); fusion, which powers the sun, releases energy by fusing two small atoms (of forms of hydrogen) together. Fusion powers the sun. Current research has brought fusion power close to the break-even point, at which the amount of energy produced by the fusion reaction is equal to the amount of energy required to bring about the fusion reaction. But fusion power plants are still years away.

The study’s authors believe a massive Apollo-style research and development program will be required to ready new power sources for the world in time to stabilize the CO2 levels in the atmosphere at a reasonable level…and time’s a-wasting.

“Combating global warming by radical restructuring of the global energy system could be the technology challenge of the century,” the authors conclude. “…Stabilizing climate is not easy. At the very least, it requires political will, targeted research and development and international cooperation. Most of all, it requires the recognition that…the fossil fuel greenhouse effect is an energy problem that cannot be simply regulated away.”

Primitive, industrial-revolution technology has gotten us into this mess; it will take advanced, futuristic technology to get us out.

Permanent link to this article: https://edwardwillett.com/2002/11/future-energy-sources/

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