There is a great deal of interest in developing cost-effective, energy-efficient and environmentally-friendly ways of producing hydrogen. If hydrogen-powered vehicles are to catch on, it is essential.
Zinc-air batteries are metal-air batteries powered by oxidizing zinc with the oxygen from the air. They have high energy densities (as much as five times more energy than lithium-ion batteries) and are more environmentally friendly. Since they are based on abundant zinc, they are potentially much cheaper to produce than the lithium-ion batteries that are used in so many current applications. But because it is difficult and expensive to produce rechargeable versions of these batteries, they have only found limited use in hearing aids, in some film cameras, and in large form to power navigation instruments, oceanographic experiments and railway signals.
Trees are nature’s way of removing carbon dioxide from the atmosphere. Growing plants take up CO2 and store it in the form of their roots, stems and leaves. And in fact, a significant factor in the growing levels of carbon dioxide in the atmosphere has been the extensive deforestation that has gone on over the past couple of centuries.
Biofuels are considered to be a sustainable alternative to fossil fuels. However, they are generally more expensive than competing fossil fuels. Government subsidies, such as we have for ethanol in this country, have been necessary to make biofuels competitive in the marketplace.