Congress is examining numerous energy sources to determine their contribution to the nation's energy portfolio and the federal role in supporting these sources. Hydropower, the use of flowing water to produce electricity, is one such source. Conventional hydropower accounted for approximately 6% of total U.S. net electricity generation in 2010. Hydropower has advantages and disadvantages as an energy source. Its advantages include its status as a continuous, or baseload, power source that releases minimal air pollutants during power generation relative to fossil fuels. Some of its disadvantages, depending on the type of hydropower plant, include high initial capital costs, ecosystem disruption, and reduced generation during low water years and seasons. Hydropower project ownership can be categorized as federal or nonfederal. The bulk of federal projects are owned and managed by the Bureau of Reclamation and the U.S. Army Corps of Engineers. Nonfederal projects are licensed and overseen by the Federal Energy Regulatory Commission (FERC). Considered by many to be an established energy source, hydropower is not always discussed alongside clean or renewable energy sources in the ongoing energy debate. However, hydropower proponents argue that hydropower is cleaner than some conventional energy sources, and point to recent findings that additional hydropower capacity could help the United States reach proposed energy, economic, and environmental goals. Others argue that the expansion of hydropower in the form of numerous small hydropower projects could have environmental impacts and regulatory concerns similar to those of existing large projects. Congress faces several issues as it determines how hydropower fits into a changing energy and economic landscape. For example, existing large hydropower infrastructure is aging; many of the nation's hydropower generators and dams are over 30 years old. Proposed options to address this concern include increasing federal funding, utilizing alternative funding, privatizing federally owned dams, and encouraging additional small-capacity generators, among other options. Additionally, whether to significantly expand or encourage expansion of hydropower is likely to require congressional input due to the uncertainty surrounding the clean and renewable energy portfolio within power markets. Potential expansion of hydropower projects could take place by improving efficiency at existing projects or by building new projects, or both. Congressional support for this approach is evident in the House passage of the Bureau of Reclamation Small Conduit Hydropower Development and Rural Jobs Act of 2012 (H.R. 2842). Senate activity on this matter includes the Hydropower Improvement Act of 2011 (S. 629), which proposes to establish a grants program for increased hydropower production, and to amend the Federal Power Act (FPA) to authorize FERC to exempt electric power generation facilities on federal lands from the act's requirements, among other things. Another issue is the rate at which FERC issues licenses for nonfederal projects, which is slower than some find ideal. The licensing process can be delayed significantly as stakeholders and the approximately dozen federal and state agencies involved give their input. FERC responded by developing a more streamlined licensing process in 2003. Still, some object to "mandatory conditions" that federal agencies can place on new or renewed hydropower facilities. The 112th Congress has introduced roughly 25 bills regarding hydropower, a quarter of which are state- or site-specific legislation.

Research on climate change has identified a wide array of sources that emit greenhouse gases (GHGs). Among the six gases that have generally been the primary focus of concern, methane is the second-most abundant, accounting for approximately 8% of total U.S. GHG emissions in 2008. Methane is emitted from a number of sources. The most significant are agriculture (both animal digestive systems and manure management); landfills; oil and gas production, refining, and distribution; and coal mining.

Climate change policies at both the national and international levels have traditionally focused on measures to mitigate greenhouse gas (GHG) emissions and to adapt to the actual or anticipated impacts of changes in the climate. As a participant in several international agreements on climate change, the United States has joined with other nations to express concern about climate change. However, in the absence of a national climate change policy, some recent technological advances and hypotheses, generally referred to as "geoengineering" technologies, have created alternatives to these traditional approaches. If deployed, these new technologies could modify the Earth's climate on a large scale. Moreover, these new technologies may become available to foreign governments and entities in the private sector to use unilaterally-without authorization from the United States government or an international treaty-as was done in the summer of 2012 when an American citizen conducted an ocean fertilization experiment off the coast of Canada. The term "geoengineering" describes this array of technologies that aim, through large-scale and deliberate modifications of the Earth's energy balance, to reduce temperatures and counteract anthropogenic climate change. Most of these technologies are at the conceptual and research stages, and their effectiveness at reducing global temperatures has yet to be proven. Moreover, very few studies have been published that document the cost, environmental effects, sociopolitical impacts, and legal implications of geoengineering. If geoengineering technologies were to be deployed, they are expected to have the potential to cause significant transboundary effects. In general, geoengineering technologies are categorized as either a carbon dioxide removal (CDR) method or a solar radiation management (SRM) method. CDR methods address the warming effects of greenhouse gases by removing carbon dioxide (CO2) from the atmosphere. CDR methods include ocean fertilization, and carbon capture and sequestration. SRM methods address climate change by increasing the reflectivity of the Earth's atmosphere or surface. Aerosol injection and space-based reflectors are examples of SRM methods. SRM methods do not remove greenhouse gases from the atmosphere, but can be deployed faster with relatively immediate global cooling results compared to CDR methods. To date, there is limited federal involvement in, or oversight of, geoengineering. However, some states as well as some federal agencies, notably the Environmental Protection Agency, Department of Energy, Department of Agriculture, and the Department of Defense, have taken actions related to geoengineering research or projects. At the international level, there is no international agreement or organization governing the full spectrum of possible geoengineering activities. Nevertheless, provisions of many international agreements, including those relating to climate change, maritime pollution, and air pollution, would likely inform the types of geoengineering activities that state parties to these agreements might choose to pursue. In 2010, the Convention on Biological Diversity adopted provisions calling for member parties to abstain from geoengineering unless the parties have fully considered the risks and impacts of those activities on biodiversity. With the possibility that geoengineering technologies may be developed and that climate change will remain an issue of global concern, policymakers may determine whether geoengineering warrants attention at either the federal or international level. If so, policymakers will also need to consider whether geoengineering can be effectively addressed by amendments to existing laws and international agreements or, alternatively, whether new laws and international treaties would need to be developed.

Wildfires are getting more severe, with more acres and houses burned and more people at risk. This results from excess biomass in the forests, due to past logging and grazing and a century of fire suppression, combined with an expanding wildland-urban interface-more people and houses in and near the forests-and climate change, exacerbating drought and insect and disease problems. Some assert that current efforts to protect houses and to reduce biomass (through fuel treatments, such as thinning) are inadequate, and that public objections to some of these activities on federal lands raise costs and delay action. Others counter that proposals for federal lands allow timber harvesting with substantial environmental damage and little fire protection. Congress is addressing these issues through various legislative proposals and through funding for protection programs. Wildfires are inevitable-biomass, dry conditions, and lightning create fires. Some are surface fires, which burn needles, grasses, and other fine fuels and leave most trees alive. Others are crown fires, which are typically driven by high winds and burn biomass at all levels from the ground through the tree tops. Many wildfires contain areas of both surface and crown fires. Surface fires are relatively easy to control, but crown fires are difficult, if not impossible, to stop; often, crown fires burn until they run out of fuel or the weather changes. Homes can be ignited by direct contact with fire, by radiative heating, and by firebrands (burning materials lifted by the wind or the fire's own convection column). Protection of homes must address all three. Research has identified the keys to protecting structures: having a nonflammable roof; clearing burnable materials that abut the house (e.g., plants, flammable mulch, woodpiles, wooden decks); and landscaping to create a defensible space around the structure. Wildland and resource damages from fire vary widely, depending on the nature of the ecosystem as well as on site-specific conditions. Surface fire ecosystems, which burn on 5- to 35-year cycles, can be damaged by crown fires due to unnatural fuel accumulations and fuel ladders (small trees and dense undergrowth); fuel treatments probably prevent some crown fires in such ecosystems. Stand-replacement fire ecosystems are those where crown fires are natural and the species are adapted to periodic crown fires; fuel treatments are unlikely to alter the historic fire regime of such ecosystems. In mixed-intensity fire ecosystems, where a mix of surface and crown fires is historically normal, it is unclear whether fuel treatments would alter wildfire patterns. Prescribed burning (intentional fires) and mechanical treatments (cutting and removing some trees) can reduce resource damages caused by wildfires in some ecosystems. However, prescribed fires are risky, mechanical treatments can cause other ecological damages, and both are expensive. Proponents of more treatment advocate expedited processes for environmental and public review of projects to hasten action and cut costs, but others caution that inadequate review can allow unintended damages with few fire protection benefits.

The use of biomass as an energy feedstock is emerging as a potentially viable alternative to address U.S. energy security concerns, foreign oil dependence, rural economic development, and diminishing sources of conventional energy. Biomass (organic matter that can be converted into energy) may include food crops, crops for energy (e.g., switchgrass or prairie perennials), crop residues, wood waste and byproducts, and animal manure. Most legislation involving biomass has focused on encouraging the production of liquid fuels from corn. Efforts to promote the use of biomass for power generation have focused on wood, wood residues, and milling waste. Comparatively less emphasis has been placed on the use of non-corn-based biomass feedstocks-other food crops, non-food crops, crop residues, animal manure, and more-as renewable energy sources for liquid fuel use or for power generation. This is partly due to the variety, lack of availability, and dispersed location of non-corn-based biomass feedstock. The technology development status and costs to convert non-corn-based biomass into energy are also viewed by some as an obstacle to rapid technology deployment. For over 30 years, the term biomass has been a part of legislation enacted by Congress for various programs, indicating some interest by the general public and policymakers in expanding its use. To aid understanding of why U.S. consumers, utility groups, refinery managers, and others have not fully adopted biomass as an energy resource, this report investigates the characterization of biomass in legislation. The definition of biomass has evolved over time, most notably since 2004. The report lists biomass definitions enacted by Congress in legislation and the tax code since 2004 and definitions contained in legislation from the 111th Congress (the American Clean Energy and Security Act of 2009, H.R. 2454; the American Clean Energy Leadership Act of 2009, S. 1462; the Clean Energy Jobs and American Power Act, S. 1733; and the discussion draft of the American Power Act). Comments on the similarities and differences among the definitions are provided. One point of contention regarding the definition is the inclusion of biomass from federal lands. Some argue that removal of biomass from these lands may lead to ecological harm. Others contend that biomass from federal lands can aid the production of renewable energy to meet certain mandates (e.g., the Renewable Fuel Standard) and that removal of biomass can enhance forest protection from wildfires. Factors that may prevent a private landowner from rapidly entering the biomass feedstock market are also included in the report. Bills were introduced in the 112th Congress that would modify the biomass definition (e.g., S. 781, H.R. 1861). However, debates about the definition have not been as extensive in the 112th Congress as they were in previous Congresses. Forthcoming discussions about energy, particularly legislation involving the Renewable Fuel Standard or energy tax incentives, may prompt further discussion about the definition of biomass.