No abstract

No abstract

A study to evaluate the feasibility of using biodiesel fuel in U.S. Army Corps of Engineers (USACE) floating plant operations to reduce environmentally sensitive emissions, increase use of renewable energy, and reduce the use of fossil fuels was conducted with funding from the U.S. Army Corps of Engineers (USACE) Dredging Operations and Environmental Research (DOER) program and the USACE Sustainability and Energy Efficiency Program. This study was conducted by the USACE Engineer Research and Development Center (ERDC) and the USACE Marine Design Center (MDC), in conjunction with support of USACE Headquarters (HQUSACE) and participating USACE Districts. The study began in 2010 with a focus on the methodology to convert four working USACE vessels to biodiesel. Favorable results in regards to mechanical and operational issues cleared the way for evaluating biodiesel on additional vessels. Fourteen vessels were converted to biodiesel use in the expanded study, and additional tests of emissions and fuel usage were conducted on two vessels. This report describes the study that successfully demonstrated that use of certified biodiesel fuel (including biodiesel manufactured from soybeans and from algal oils) by suitable USACE floating plants is feasible to reduce select environmentally sensitive emissions, increase USACE use of renewable energy, and reduce the use of fossil fuels.

Mudbanks have been observed to have an extraordinary calming effect on the sea surface. In certain cases this effect is due primarily to the transfer of energy through the sea/mud interface and its frictional dissipation within the bottom sediments. This paper describes an experiment that measured wave characteristics and the resulting sea floor oscillations in an area where the bottom is composed of fine-grained sediments. The energy lost by the waves at the position of the experimental setup is calculated and compared with a direct measurement of the net energy lost by the waves in going from the point of the experiment to a station 3.35 km inshore. Results show that bottom motions in the range of wave-induced bottom pressures from near zero to 2.39 x 10-3 Pascal have the appearance of forced waves on an elastic half space. The apparent effect of internal viscosity is seen in a phase shift between the crest of the pressure wave and the trough of the mud wave. Measurements show this angle to be 22° (ill") for the peak spectral component (T = 7.75 seconds). The energy lost to the bottom by the waves at the field site was found to be at least an order of magnitude greater than that resulting from the processes of percolation or that caused by normal frictional effects. This newly observed mechanism for the dissipation of wave energy is particularly important for waves in intermediate-depth water and could be a prime factor in determining design wave heights in muddy coastal areas.

No abstract