A clear objective of NHES is better to utilize our natural resources, reducing withdrawals from the environment and impact on the environment due to waste stream emissions. One aspect of this environmental stewardship is the reduction of greenhouse gas (GHG) emissions. This is commonly measured in terms of the equivalent amount of CO2 emitted when all GHG are summed and adjusted based on their energy adsorption capacity.

Total water withdrawal for an ecosystem is becoming increasingly important, especially in consideration of the impact of erratic weather patterns and atmospheric temperature excursions that affect the available surface water at a given location. In arid climates where surface waters are practically nonexistent or where ground water withdrawals have already drained subterrain aquifers, water conservation is an essential requirement. Higher-temperature advanced reactors (non-water cooled) operate at higher efficiencies than traditional LWR systems, resulting in less waste heat that must be ejected to the environment. This not only reduces the thermal output to the environment, but it also reduces the water loss in the condenser cooling loop.

Land withdrawals are defined as permanent alteration to land that results from installation of the facility, such as modification of mountain tops to install wind capacity, disposal of coal ash waste that results from coal combustion (typically dumped into landfills or ash ponds near coal-fired power plants), or clearing land based on the required plant footprint and associated exclusion zone. These modifications can impact an ecosystem just as much as waste emissions, including long-term life­cycle impacts on resident species. The adverse effects of ejecting waste heat to the environment are an additional environmental consideration.

Environmental impacts could be due to resource or feedstock extraction or production; impact of emissions, including both gaseous emissions and ejection of high-temperature water; or impact of energy transmission requirements. Electricity production located at some distance from the end user may require the installation of a new long-distance high-voltage power line in some regions, but rail transportation of an energy product (e. g. hydrogen, synthetic fuels) might have fewer regulatory constraints and lower environmental impact.

Environmental stewardship requires that the build-out of modern energy infrastructure consider the long-term outlook for scarce resources, such as water, land, carbon feedstock, etc. Unfortunately, the long-term horizon is often overlooked or underemphasized. Evaluation and design of tightly coupled, small-scale hybrid energy systems focus on selecting system configurations that are environmentally responsible while meeting the demand for a variety of energy commodities.