Energy is main topic in the 'Grand Challenges of Engineering'

The top three challenges in this list are related to energy

What are the grand challenges that await engineering solutions in the century ahead? How can engineers put knowledge into practice to ensure sustainability, health, safety and quality of life for the generations to come?

The U.S. National Academy of Engineering (NAE) assembled a diverse panel of experts from around the world to answer these questions. The members are some of the most accomplished engineers and scientists of their generation. They proposed fourteen 'challenges for engineering' that they consider both achievable and sustainable.

It is significant that the first three challenges mentioned in the report are all related to energy. This focus is immediately apparent in the report’s Introduction: 'The Earth is a planet of finite resources, and its growing population currently consumes them at a rate that cannot be sustained. Widely reported warnings have emphasised the need to develop new sources of energy, at the same time as preventing or reversing the degradation of the environment.' The expert panel saw three main engineering challenges that could satisfy this need:

1. making solar energy with energy storage economical;
2. providing energy from nuclear fusion;
3. developing carbon sequestration methods.

Making solar energy economical

The energy of the sun’s radiation on earth is abundant, but the challenge is how to convert this solar energy into a useful form in an economic way. Today, electricity from solar energy still costs roughly three to six times more than the average grid electricity price.

According to the expert panel, engineering could boost solar energy in three ways:

• The efficiency of photovoltaic (PV) panels could be improved. The silicon cells currently used only convert sunlight into electricity at an efficiency rate of 10 to 20 per cent. New materials, arranged in novel ways, have the potential to double that rate, and by making use of nano-crystals, efficiencies of 60 per cent could theoretically be reached.
• The manufacturing costs of PV panels could be reduced. To enable the flow of electrons, the silicon used in PV panels must be of high purity, resulting in high manufacturing costs. The challenge is to construct PV cells out of a thinner layer of material without conceding levels of efficiency.
• New efficient energy storage systems could be developed. Energy storage becomes critical when high amounts of intermittent sources, such as solar power, are connected to the electricity grid. The development of new materials could improve capacitors, superconducting magnets, and flywheels. Other new materials could enhance the efficiency of thermal storage systems for use in thermal concentration solar power stations. Another possible future solution is to use sunlight to power the electrolysis of water, generating hydrogen that can power fuel cells.

Providing energy from nuclear fusion

Along with making use of the sun’s radiation for our energy needs, we could also artificially re-create its power source, namely nuclear fusion. Although the theory of nuclear fusion has already been well known for more than fifty years, using fusion for commercial purposes stretches the limits of current engineering ingenuity.

A major test facility, the International Thermonuclear Experimental Reactor (ITER) is currently being built in the south of France. It aims at producing a long pulse of energy release out of the fusion of deuterium and tritium. The required deuterium can be produced from water. Tritium — a radioactive material — can be produced out of lithium. The fuels are heated to a plasma state and compressed by magnetic forces.

It is hoped that the new test facility will enable the solving of various technical and safety issues. Among other things, superconducting magnets will have to be improved and advanced vacuum techniques developed. Methods will also be needed for confining the radioactivity from fast flying neutrons within the reactor. Moreover, releases of radioactive tritium fuel will have to be prevented. In a later stage, one of the challenges will be to replace tritium with a new generation of fuel and thus reduce radioactivity by several orders of magnitude.

Developing carbon sequestration methods

Until engineers are able to overcome the practical barriers of solar power and nuclear fusion, fossil fuels will remain the primary source of energy. To limit the impact on climate change of this continued use of fossil fuels, methods are being developed for capturing the carbon dioxide from combustion emissions and storing it underground.

The NAE panel of experts sees three principal avenues to be investigated for carbon capture:

• Using chemicals to isolate the carbon dioxide from the other gasses, and then separating the carbon dioxide from the absorbing chemicals.
• Burning coal in pure oxygen, making the separation of carbon dioxide from the exhaust gases much easier. This shifts the problem to discovering an economically viable method of mass producing pure oxygen.
• Making use of coal gasification, producing hydrogen and carbon monoxide. By adding steam and a catalyst, the carbon monoxide can be transformed into additional hydrogen and carbon dioxide. The latter can be filtered out of the system, while the hydrogen can be burned in a gas turbine to produce electric power.

For carbon storage, the following tracks are being investigated:

• Storing the carbon dioxide in old gas and oil fields. However, those fields do not presently have enough capacity if carbon sequestration would become common practice.
• Storing it in sedimentary brine formations more than 800 metres underground. This kind of storages will have to be secure enough to store the carbon dioxide for centuries or millennia. It will be an engineering and geological challenge to choose and monitor such sites carefully.
• Injecting the carbon dioxide in sediments beneath the ocean floor. High pressure from the ocean will keep the carbon dioxide inside the sediments. In this case, the challenge is mainly to develop a cost effective technique.

Apart from the above tracks, new techniques for sequestering carbon dioxide could solve both the capture and the storage issues. One such proposed technique is to fix carbon dioxide in limestone rocks.

Harvard geoscientist Daniel Schrag declares in the NAE report that the chances of success for carbon sequestration are high. 'Scientific and economic challenges still exist,' he declares, 'but none are serious enough to suggest that carbon capture and storage will not work at the scale required to offset trillions of tons of carbon dioxide emissions over the next century.'

Reference

Website on the Grand Challenges of Engineering by the U.S. National Academy of Engineering (NAE)

Comments

The higher cost of solar energy is only partly a problem of engineering or technology. Public policy also needs to change. Starting by placing a value on one of the key advantages of solar energy -- close to zero pollution outputs. Right now no monetary value is placed on this tremendous advantage. We also need to look at direct and indirect subsidies for the oil, coal, and nuclear industries. If we phased out those subsidies over time, solar energy would seem much more price competitive.

John Howley
President & CEO
Davies Energy Systems, Inc.
www.daviesenergy.com

• Log in to post comments

By john.howley 28/10/2010