5.2. Impact of carbon incentives A key benefit e and driver e for renewable energy projects is that there is little to no carbon dioxide emission associated with the electricity generating process. This is in stark contrast to electricity produced from fossil fuels, which can range between 100 and 250 g/kWh of electricity generated. In 2008 2359 million metric tons of carbon dioxide were emitted from electricity generating processes, accounting for over 40% of the total carbon dioxide emissions. Along with reducing energy consumption, renewable energy technologies will also play a key role in reducing carbon dioxide emissions. In order to curb carbon dioxide emissions, a series of incentives have been developed including renewable energy (REC) and carbon emission21 credits. In each case, the owner of a renewable energy system earns credits for every 1 kWh of electricity generated, or for every ton of carbon that is offset. Excess credits can then be sold to other entities as a commodity. In this analysis I did not investigate the impact of these credits due to the lack of a developed and coherent REC or carbon credit trading scheme in the United States. Both of these markets have been volatile, particularly because of recent global financial concerns. Furthermore, carbon credits and REC trading remain largely voluntary in the United States. Another alternative is to implement a carbon tax. This concept is not new, and is based on the economic principle of negative externalities. Externalities are costs or benefits generated by the production of goods and services. Negative externalities are costs that are not paid for. When utilities, businesses or homeowners consume energy generated from fossil fuels, they create pollution that has a societal cost; everyone suffers from the effects of pollution. Countries in the European Union have implemented carbon taxes as early as 1990. Even in the United States there are two examples of cities that have implemented carbon taxes e San
Francisco, California in200822 and Boulder, Colorado in 200623. It is likely that as carbon taxes become commonplace, installing RES may become more attractive and viable options for carbon management. Currently, the United States on a national level does not have a carbon tax in place. However, the effects of such a tax can be modeled using CO2 prices from various carbon exchanges such as the Chicago Climate Exchange (CCX), European Climate Exchange, or even national carbon taxes from countries around the world. Examples of existing national carbon taxes are shown in Fig. 5. Again, in this analysis, we did not examine the impact of introducing a carbon tax on the financial viability of the solar PV arrays. Throughout this analysis, we operated with the assumption that the objective was to examine whether a moderately sized college campus could achieve net-zero energy operations using only solar PV.