The Geothermal Power Plants of Amiata Volcano, Italy: Impacts on Freshwater Aquifers, Seismicity and Air

Production of geothermal energy for electricity at Amiata Volcano uses flash-type power plants with cooling towers that evaporate much of the geothermal fluid to the atmosphere to condense the geothermal vapour extracted. Because the flash occurs also within the geothermal reservoir, it causes a significant depressurization within it that, in turns, results in a drop of the water table inside the volcano between 200 and 300 m. The flow rates of natural springs around the volcano have also substantially decreased or ceased since the start of geothermal energy exploitation. Continuous recording of aquifer conditions shows substantial increases in salinity (>20%) and temperature (>2°C) as the water table falls below about 755–750 m asl. In addition to hydrologic impacts, there are also a large numbers of induced earthquakes, among which the ML 3.9, April 1, 2000 earthquake that generated significant damage in the old villages and rural houses. Relevant impacts on air quality occur when emissions are considered on a per-MW basis. For example, CO2+CH4 emissions at Amiata are comparable to those of gas-fired power plants (1), while the acid-rain potential is about twice that of coal-fired power plants. Also, a significant emission of primary and secondary fine particles is associated with the cooling towers. These particles contain heavy metals and are enriched in sodium, vanadium, zinc, phosphorous, sulphur, tantalium, caesium, thallium, thorium, uranium, and arsenic relative to comparable aerosols collected in Florence and Arezzo (2). Measurements have shown that mercury emitted at Amiata comprises 42% of the mercury emitted from all Italian industries, while an additional comparable amount is emitted from the other geothermal power plants of Tuscany (3). We believe that the use of air coolers in place of the evaporative cooling towers, as suggested in 2010 by the local government of Tuscany (4), could have and can now drastically reduced the environmental impact on freshwater and air. On the opposite side of the coin, air-coolers would increase the amount of reinjection, increasing the risk of induced seismicity. We conclude that the use of deep borehole heat exchangers could perhaps be the only viable solution to the current geothermal energy environmental impacts.

Hydrologic Impacts of Climate Change in Relation to Ontario’s Source Water Protection Planning Program

Water management activities are currently predicated on the assumption of a stationary climate, despite the reality of climate change. Hydrologic impacts of climate change for three sub-watersheds north of Toronto for 2041-70 were investigated using the Precipitation-Runoff Modeling System to model six GCM projections from each of RCP 2.6, RCP 4.5, and RCP 8.5. Annual groundwater recharge, evapotranspiration, and the 7Q20 low streamflow statistic were projected to change from 1976-2005 conditions by -2.2% to +20.5%, +0.9% to +14.4%, and -25.5% to +9.8%, respectively. Seasonal shifts included an earlier date of peak streamflow for the majority of simulations and a +14.0% to +103.9% increase in winter recharge. A steady-state MODFLOW model was employed as a preliminary assessment into the effects of climate change on Source Water Protection outputs. The results of this research further the understanding of climate change impacts on human and ecological systems in southern Ontario.

IMPACTS OF BEETLE KILL ON MODELED STREAMFLOW RESPONSE IN THE NORTH PLATTE RIVER BASIN

A beetle epidemic across the western United States has resulted in the death of millions of acres of forests. This beetle outbreak, referred to as “beetle kill”, has caused many to believe that such dramatic changes in land cover could potentially alter the hydrology of the impacted regions. One of the most important hydrological processes that beetle kill has the potential to impact is streamflow. This research evaluates the hydrologic impacts on streamflow from land cover change due to beetle kill in the North Platte River Basin (NPRB) (Colorado and Wyoming, USA) by utilizing the Variable Infiltration Capacity (VIC) hydrologic model. Utilizing the National Agricultural Imagery Program (NAIP) dataset from 2005 / 2006 (onset of “beetle kill”) to more current conditions (2009), a decrease in tree cover of 16% to 40% was estimated. This decrease in tree cover was applied to VIC modeled streamflow from 1950 to 2000. The VIC model predicted a minimal increase in streamflow of approximately 5% which was not statistically significant.