The steep slope levels off when cell phone market penetration reaches 100 percent, and the only relevant factor after that is the population growth Landlines Only Now we alter our model such that the Initial State of a household still involves having no hones, and the Final State involves having one landline. We take the previous graph and overlay a graph generated from a simulation that assumes the nation's households will adopt landlines instead of cell phone 1400 1200 ,-------:--- Based solely on this graph, the Landlines Only plan seems optimal, since it requires less than half the power of the Cell Phones Only plan. However, we prefer to delay our recommendation First, we examine a way to make cell phone adoption more energy efficient Wasteful Charging and "Vampire"Chargers Although the above comparative analysis of the two plans shows Landlines Only to be a clear winner,we should take into account that the rate at which cell phones consume energy varies depending on the practices of cell phone users. Until now, we have assumed that the energy consumption of a cell phone is equal to the consumption of its charger -even though many people do not use their charger as conservatively as they could. We now relax this assumption and assess the total cost of certain wasteful practices by supposing that our hypothetical mation's citizens never charge a cell phone after it is finished charging The UMAP Journal 30(3)(2009). @Copyright 2009 by COMAP, Inc. All rights reservedThe steep slope levels off when cell phone market penetration reaches 100 percent, and the only relevant factor after that is the population growth. Landlines Only Now we alter our model such that the Initial State of a household still involves having no phones, and the Final State involves having one landline. We take the previous graph and overlay a graph generated from a simulation that assumes the nation’s households will adopt landlines instead of cell phones. 0 200 400 600 800 1000 1200 1400 1600 ’10 ’12 ’14 ’16 ’18 ’20 ’22 ’24 ’26 ’28 ’30 Power Consumption (Megawatts) Time Cell Phone Nation Landline Nation Figure 7. Based solely on this graph, the Landlines Only plan seems optimal, since it requires less than half the power of the Cell Phones Only plan. However, we prefer to delay our recommendation. First, we examine a way to make cell phone adoption more energy efficient. Wasteful Charging and “Vampire” Chargers Although the above comparative analysis of the two plans shows Landlines Only to be a clear winner, we should take into account that the rate at which cell phones consume energy varies depending on the practices of cell phone users. Until now, we have assumed that the energy consumption of a cell phone is equal to the consumption of its charger – even though many people do not use their charger as conservatively as they could. We now relax this assumption and assess the total cost of certain wasteful practices by supposing that our hypothetical nation’s citizens never • charge a cell phone after it is finished charging. The UMAP Journal 30 (3) (2009). ©Copyright 2009 by COMAP, Inc. All rights reserved