Hydropower: renewable? Ecofriendly?

Anyone interested in the important issues around global climate change quickly comes to appreciate that the modes of energy generation vary greatly with respect to the extent to which they contribute to global warming.

Fossil fuels make the largest contribution to global warming for a given amount of energy produced, because greenhouse gases are formed as the fuels are burned, as in coal-fired or natural gas fired power plants that generate electricity.  Fossil fuels of course also power cars, trucks and other things.  Ethanol, a component of automobile gasoline is in the same league; not only is carbon dioxide produced when ethanol is burned, enormous amounts of energy, mostly derived from fossil fuels, is needed to produce the ethanol. The notion that ethanol is a renewable source of energy is a distraction. True, it is a plant product; carbon dioxide was taken from the atmosphere by the corn plants. But the expenditure of all the energy required to get it to the gas pump, and the environmental costs of producing the corn and getting ethanol from it, more than null out that argument.

The urgent need to reduce emissions of carbon dioxide drives the effort to replace fossil fuels with alternative sources of energy. We speak of renewable sources, but what does that mean?  Renewable energy is generated from natural processes that are continuously replenished, such as sunlight, wind, oceanic tides. It's common to include biomass such as wood, plants such as corn or soy and other crops in this category, but the points I made with respect to ethanol apply to many of these sources as well.   

If we had a government more inclined to advance the long-term welfare of the people who put their faith in it, we would have continuing, substantial investments in developing newer, more effective means of generating renewable energy. Unfortunately, government often gets in the way of progress. Nonetheless, the private sector has made substantial advancements in achieving ever more efficient conversion of sunlight into electrical energy, and more efficient and environmentally friendly wind generators.  If we could get certain state governments to enact progressive policies and regulations for deploying solar panels more extensively, we could be even farther along than we are.  What is clear is that the technologies of both solar and wind power are making huge gains.  Our dependence on fossil fuels is shrinking steadily, despite powerful corporate and political fossil fuel interests bent on slowing progress.

 But, we have yet a long way to go, and there remains one big problem with both wind and solar: the wind doesn’t always blow, and the sun sometimes is not to be seen.  It is devilishly difficult to store electrical energy in large quantities so that it can be used later.  Rechargeable batteries might seem like a good solution, but on a large scale, it just isn’t going to work.  We need energy sources that are capable of getting us through the night, as it were. Of course, the sun’s always shining somewhere, and the wind’s always blowing somewhere, but transport of electricity across long distances is difficult, and has its own environmental challenges.

Until now, the two major alternatives to fossil fuels have been hydroelectric and nuclear power. Each of these deserves a discussion. In this blog I’ll confine my comments to hydropower, as it’s commonly called.

Despite increased deployment of solar and wind power generation, hydropower is the largest source of renewable energy worldwide. You get it by creating a large basin, placing a dam at the outlet end of it, and using the energy created by the water’s fall from the top of the dam to the lower level to generate electricity.  As long as we can keep enough water in the basin, and a suitable flow for the water once it’s gone over the top, we should be good.  But there are problems, starting with the fact that the land required to form the basin sometimes displaces people and is taken out of use for food production. Nevertheless, power-hungry China has already built more than 200 gigawatts of hydroelectric power generation, and another 230 gigawatts is under construction, development or permitting.  Taken together this amounts to the capacity of about 85 of the largest coal-fired power plants ever built. Other Asian nations, especially India, are following China’s lead.

In the US, hydropower has long been the most important renewable source of electricity.  It’s interesting in light of this fact that the US is low on the list of nations with large dam projects.  Worldwide, according to size, Grand Coulee Dam is #7, and only 5 other US dams are on the list of the top 70. Many of our largest ones have been controversial in terms of their impacts on the environment and the uses of precious water resources affected by their presences. Hoover dam and Lake Mead, its associated water reservoir, is one of the earliest and largest dam projects.  The dam was completed during the 1930s, and is still the 6^th largest hydroelectric facility in the US. This project is often in the limelight because of the heavy demands made on Lake Mead, the biggest reservoir in the Colorado River system that irrigates Southern California crops and provides drinking water to some 40 million people. A protracted drought in the Southwest has resulted in a drop of more than 140 feet in the lake’s level, to 1080 feet above sea level.  In January 2017, Hoover dam was operating at about only 39 percent of capacity.  Improvements in the design of the turbines will make it possible to operate the dam at lake levels as low as 950 feet, but competition for the water will be vicious.  

The example of Hoover dam illustrates the connection between hydropower and global climate change.  A signature characteristic of global warming is drought in many of the world's settled regions. The Yangtze, China’s longest river, is at its lowest level in the history of recording it. There are water shortages in many parts of China, affecting agriculture and the availability of water for human consumption.  What happens when there’s not enough to sustain needed water levels for the big new dams? Hydropower is a renewable source of energy in that the water it requires is transported globally by the global climate machine, driven by solar energy, that ultimately moves water from tropical regions toward the poles. The workings of that machinery are being altered by global warming, with results that may be dire for humankind.

Before we leave the topic of hydropower, here’s another problem:  dams accumulate silt over time and lose their effectiveness as power sources if that sediment is not removed. Add up all the existing and potential problems, and it’s clear that hydropower is far from a panacea for our energy needs.  Life can be difficult!  The next blog I post will concern itself with the vexing pros and cons of nuclear power. There's some interesting stuff going on in this area.

When will it be too late?

Elizabeth Kolbert is one of the journalist stalwarts of the environmental movement. In her incisive book, The Sixth Extinction,  she shows how human beings have altered life on Earth in ways that no other species has done before. She argues that a massive extinction of higher planetary life forms is likely to be mankind’s legacy. A dozen years ago, in Field Notes from a Catastrophe, she attempted to bring attention to the causes and effects of global climate change.  Her account provides little cause for optimism, nor does her 2017 piece in the New Yorker on the intransigence of human judgment in the face of evidence and logical thought.  The increasing flow of warning signals from climatologists, oceanographers, and soil scientists, to name just a few of the many scientific disciplines involved, gives us strong reasons to believe that the global climate is changing and that the space we have for responsive action is shrinking. But how substantial is this evidence?

The Intergovernmental Panel on Climate Change (IPCC), the UN body for assessing the science related to climate change, is celebrating its 30th anniversary in 2018. Scientists from all over the world contribute to the work of the IPCC, lending their expertise to the many working groups studying one or another aspect of climate change. Individual groups of scientists also publish the results of their studies in peer-reviewed scientific journals. The result is a staggering amount of information that must be correlated and brought into coherence to form a model as reliable as possible of how the global climate is changing, particularly in response to anthropogenic influences—man-made effects. Many of the findings published by the IPCC, inherently conservative because of the need to accommodate different perspectives, point to a dire future unless steps are taken to substantially reduce greenhouse gas emissions within the next couple of decades.  

So we have on the one hand a chorus of voices calling for changes in the ways human society lives, in all locations, and at all levels of wealth, to cooperatively reduce greenhouse gas emissions. On the other hand, the developed world is so heavily invested in carbon-based fuels as sources of energy, and the design of the energy economy, that a massive shift into renewable sources seems out of reach.  It seems that at best, we can anticipate a gradual increase in the use of renewables, a less than forceful research agenda aimed at new ways to store renewable energy, and weak policies addressing energy efficiency.

If we keep on as we have, nature will eventually have its way. For starters, sea levels will rise to drown most of the Solomon Islands, coastal regions all over the globe will suffer frequent disastrous flooding, hurricanes will be more frequent and nastier than ever, heat waves and drought will become regular summer visitors to formerly more verdant and livable lands.  If human society waits to take remedial action when all that has come to pass—well, good luck! The damage will already have been done. Ocean levels will be several feet higher than at present and continuing to rise. High levels of greenhouse gases, notably carbon dioxide, will persist for many decades—we won’t be able to just suck it all back and bury it underground.   I say “we”, but I don’t mean you and me, dear reader. We will have departed and left our progeny with the challenges of coping with a much smaller and poorer world.

Maybe the source of the vexing lack of public interest in global warming, aside from propaganda from the fossil fuel industries, lies in our moral torpor:  it’s not going to be our problem, at least not to a great extent. Someone else will have to deal with it.  Heck, we don’t even know those great-great grandchildren!  They’ll figure something out.  But we can do much better than that.  In my next blog I want to return to a topic I mentioned earlier and bring us up to date on Project Drawdown; a movement of great promise that we can all get behind.