Answer to Question 1
Although hydrogen could possibly be an inexhaustible resource for energy, determining a cost-effective, safe, and efficient way to use hydrogen as a fuel presents a major challenge. New solutions on the horizon, as discussed in this chapter, do present promise.
Answer to Question 2
If producers were killed in an ecosystem, the entire ecosystem would suffer greatly, because they provide energy in the form of food to the various consumers in the ecosystem. In very quick order the consumers in every trophic level would be unable to find adequate food sources for their survival and would perish.
If decomposers and detritus feeders were eliminated from an ecosystem, nutrient cycling would not happen at the rates necessary to replenish the soil and provide nutrients necessary for the producers to survive. This scenario would eventually feed back to all of the consumers in the ecosystem as well.
Due to the fact that all organisms in the ecosystem are closely tied together by way of the food web and predator-prey relationships, the loss of any type of organism will cause a great disturbance and an accumulation of negative events in the ecosystem.