The spatial energy spectrum of the 110-150 km region is evaluated using a base case run of the NCAR-TIGCM. Available potential energy, divergent kinetic energy, and rotational kinetic energy are decomposed into spherical harmonic modes and the relative sizes of the reservoirs are compared to those observed in the lower atmosphere. The lower thermospheric spectrum is dominated by the signals of diurnal and semidiurnal tides, but dissipation occurs within the study region. The total potential energy exceeds the available potential energy by three orders of magnitude, but unlike the tropospheric case, more energy resides as kinetic energy than as available potential energy, a result that is typical of propagating tides. A modified definition of available potential energy apprpriate for thermospheric heights is presented.