Can your city run on plants?
We get energy from plants all the time. In fact, we are energy from plants. But what new ways can we use plant energy, or biomass, on a large scale. Scientists and engineers are working on that right now. They're developing syngas for large-scale production of electricity, liquid fuel for use in cars and trucks, and compressing industrial waste sawdust for use as biomass heating pellets.
It may sound strange, but the CO2 released from biomass is better than CO2 released from fossil fuels. How so? Like water in the water cycle, carbon has its own natural cycle. First, plants take in CO2 from the air as food. When they die, that CO2 returns to the atmosphere. But growing plants absorb a roughly similar amount of CO2, essentially trading CO2 back and forth. By contrast, the carbon in coal, oil and gas is trapped outside this cycle and therefore outside the atmosphere. Digging and burning these fossil fuels increases total CO2 in the atmosphere.
How do fuel cells work?
To begin, natural gas (usually methane) is supplied to the fuel cell. Steam (which is a by-product of the system, see below) is used to reform the natural gas into hydrogen-rich gas.
A catalytic reaction converts the hydrogen into protons and electrons with the positively charged protons passing through the fuel cell electrolyte.
The negatively charged electrons flow through an external circuit to produce electricity. This DC power is then conditioned to provide high-quality AC output power.
The electrons and protons then recombine with oxygen from the air to create water, which is put back into the system as steam. That leaves the remaining by-product - heat.
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