Commodities / Renewable Energy Oct 28, 2012 - 06:53 AM By: Nicole_Foss
In recent years, there has been more and more talk of a transition to renewable energy on the grounds of climate change, and an increasing range of public policies designed to move in this direction. Not only do advocates envisage, and suggest to custodians of the public purse, a future of 100% renewable energy, but they suggest that this can be achieved very rapidly, in perhaps a decade or two, if sufficient political will can be summoned. See for instance this 2009 Plan to Power 100 Percent of the Planet with Renewables:
A year ago former vice president Al Gore threw down a gauntlet: to repower America with 100 percent carbon-free electricity within 10 years. As the two of us started to evaluate the feasibility of such a change, we took on an even larger challenge: to determine how 100 percent of the world’s energy, for all purposes, could be supplied by wind, water and solar resources, by as early as 2030.
See also, as an example, the Zero Carbon Australia Stationary Energy Plan proposed by Beyond Zero Emissions:
The world stands on the precipice of significant change. Climate scientists predict severe impacts from even the lowest estimates of global warming. Atmospheric CO2 already exceeds safe levels. A rational response to the problem demands a rapid shift to a zero-fossil-fuel, zero-emissions future. The Zero Carbon Australia 2020 Stationary Energy Plan (the ZCA 2020 Plan) outlines a technically feasible and economically attractive way for Australia to transition to a 100% renewable energy within ten years. Social and political leadership are now required in order for the transition to begin.
The Vision and a Dose of Reality
These plans amount to a complete fantasy. For a start, the timescale for such a monumental shift is utterly unrealistic:
Perhaps the most misunderstood aspect of energy transitions is their speed. Substituting one form of energy for another takes a long time….The comparison to a giant oil tanker, uncomfortable as it is, fits perfectly: Turning it around takes lots of time.
And turning around the world’s fossil-fuel-based energy system is a truly gargantuan task. That system now has an annual throughput of more than 7 billion metric tons of hard coal and lignite, about 4 billion metric tons of crude oil, and more than 3 trillion cubic meters of natural gas. And its infrastructure—coal mines, oil and gas fields, refineries, pipelines, trains, trucks, tankers, filling stations, power plants, transformers, transmission and distribution lines, and hundreds of millions of gasoline, kerosene, diesel, and fuel oil engines—constitutes the costliest and most extensive set of installations, networks, and machines that the world has ever built, one that has taken generations and tens of trillions of dollars to put in place.
It is impossible to displace this supersystem in a decade or two—or five, for that matter. Replacing it with an equally extensive and reliable alternative based on renewable energy flows is a task that will require decades of expensive commitment. It is the work of generations of engineers.
Even if we were not facing a long period of financial crisis and economic contraction, it would not be possible to engineer such a rapid change. In a contractionary context, it is simply inconceivable. The necessary funds will not be available, and in the coming period of deleveraging, deflation and economic depression, much-reduced demand will not justify investment. Demand is not what we want, but what we can pay for, and under such circumstances, that amount will be much less than we can currently afford. With very little money in circulation, it will be difficult enough for us to maintain the infrastructure we already have, and keep future supply from collapsing for lack of investment.
Timescale and lack of funds are by no means the only possible critique of current renewable energy plans, however. It is not just a matter of taking longer, or waiting for more auspicious financial circumstances. It will never be possible to deliver what we consider business as usual, or anything remotely resembling it, on renewable energy alone. We can, of course, live in a world of renewable energy only, as we have done through out most of history, but it is not going to resemble the True Believers' techno-utopia. Living on an energy income, as opposed to an energy inheritance, will mean living within our energy means, and this is something we have not done since the industrial revolution.
Technologically harnessable renewable energy is largely a myth. While the sun will continue to shine and the wind will continue to blow, the components of the infrastructure necessary for converting these forms of energy into usable electricity, and distributing that electricity to where it is needed, are not renewable. Affordable fossil fuels are required to extract the raw materials, produce the components, and to build and maintain the infrastructure. In other words, renewables do not replace fossil fuels, nor remove the need for them. They may not even reduce that need by much, and they create additional dependencies on rare materials.
Renewable energy sounds so much more natural and believable than a perpetual-motion machine, but there's one big problem: Unless you're planning to live without electricity and motorized transportation, you need more than just wind, water, sunlight, and plants for energy. You need raw materials, real estate, and other things that will run out one day. You need stuff that has to be mined, drilled, transported, and bulldozed -- not simply harvested or farmed. You need non-renewable resources:
• Solar power. While sunlight is renewable -- for at least another four billion years -- photovoltaic panels are not. Nor is desert groundwater, used in steam turbines at some solar-thermal installations. Even after being redesigned to use air-cooled condensers that will reduce its water consumption by 90 percent, California's Blythe Solar Power Project, which will be the world's largest when it opens in 2013, will require an estimated 600 acre-feet of groundwater annually for washing mirrors, replenishing feedwater, and cooling auxiliary equipment.
• Geothermal power. These projects also depend on groundwater -- replenished by rain, yes, but not as quickly as it boils off in turbines. At the world's largest geothermal power plant, the Geysers in California, for example, production peaked in the late 1980s and then the project literally began running out of steam.
• Wind power. According to the American Wind Energy Association, the 5,700 turbines installed in the United States in 2009 required approximately 36,000 miles of steel rebar and 1.7 million cubic yards of concrete (enough to pave a four-foot-wide, 7,630-mile-long sidewalk). The gearbox of a two-megawatt wind turbine contains about 800 pounds of neodymium and 130 pounds of dysprosium -- rare earth metals that are rare because they're found in scattered deposits, rather than in concentrated ores, and are difficult to extract.
• Biomass. In developed countries, biomass is envisioned as a win-win way to produce energy while thinning wildfire-prone forests or anchoring soil with perennial switchgrass plantings. But expanding energy crops will mean less land for food production, recreation, and wildlife habitat. In many parts of the world where biomass is already used extensively to heat homes and cook meals, this renewable energy is responsible for severe deforestation and air pollution.
• Hydropower. Using currents, waves, and tidal energy to produce electricity is still experimental, but hydroelectric power from dams is a proved technology. It already supplies about 16 percent of the world's electricity, far more than all other renewable sources combined….The amount of concrete and steel in a wind-tower foundation is nothing compared with Grand Coulee or Three Gorges, and dams have an unfortunate habit of hoarding sediment and making fish, well, non-renewable.
All of these technologies also require electricity transmission from rural areas to population centers…. And while proponents would have you believe that a renewable energy project churns out free electricity forever, the life expectancy of a solar panel or wind turbine is actually shorter than that of a conventional power plant. Even dams are typically designed to last only about 50 years. So what, exactly, makes renewable energy different from coal, oil, natural gas, and nuclear power?
Renewable technologies are often less damaging to the climate and create fewer toxic wastes than conventional energy sources. But meeting the world's total energy demands in 2030 with renewable energy alone would take an estimated 3.8 million wind turbines (each with twice the capacity of today's largest machines), 720,000 wave devices, 5,350 geothermal plants, 900 hydroelectric plants, 490,000 tidal turbines, 1.7 billion rooftop photovoltaic systems, 40,000 solar photovoltaic plants, and 49,000 concentrated solar power systems. That's a heckuva lot of neodymium.
In addition, renewables generally have a much lower energy returned on energy invested (EROEI), or energy profit ratio, than we have become accustomed to in the hydrocarbon era. Since the achievable, and maintainable, level of socioeconomic complexity is very closely tied to available energy supply, moving from high EROEI energy source to much lower ones will have significant implications for the level of complexity we can sustain. Exploiting low EROEI energy sources (whether renewables or the unconventional fossil fuels left to us on the downslope of Hubbert's curve) is often a highly complex, energy-intensive activity.
As we have pointed out before at TAE, it is highly doubtful whether low EROEI energy sources can sustain the level of socioeconomic complexity required to produce them. What allows us to maintain that complexity is high EROEI conventional fossil fuels - our energy inheritance.
Power systems are one of the most complex manifestations of our complex society, and therefore likely to be among the most vulnerable aspects in a future which will be contractionary, initially in economic terms, and later in terms of energy supply. As we leave behind the era of cheap and readily available fossil fuels with a high energy profit ratio, and far more of the energy we produce must be reinvested in energy production, the surplus remaining to serve all society's other purposes will be greatly reduced. Preserving power systems in their current form for very much longer will be a very difficult task.
It is ironic then, that much of the vision for exploiting renewable energy relies on expanding power systems. In fact it involves greatly increasing their interconnectedness and complexity in the process, for instance through the use of 'smart grid' technologies, in order to compensate for the problems of intermittency and non-dispatchability. These difficulties are frequently dismissed as inconsequential in the envisioned future context of super grids and smart grids.
The goal of modern power systems is to balance supply and demand in real time over a whole AC grid, which is effectively a single enormous machine operating in synchrony. North America, for instance, is served by only four grids - the east, the west, Texas and Quebec. System operators, who have little or no control over demand, rely on being able to control sources of supply in order to achieve the necessary balance and maintain the stability of the system.
Power systems have been designed on a central station model, with large-scale generation in relatively few places and large flows of power carried over long distances to where demand is located, via transmission and distribution networks. Generation must come on and off at the instruction of system operators. Plants that run continuously provide baseload, while other plants run only when demand is higher, and some run only at relatively rare demand peaks. There must always be excess capacity available to come on at a moment's notice to cover eventualities. Flexibility varies between forms of generation, with inflexible plants (like nuclear) better suited to baseload and more flexible ones (like open-cycle gas plants) to load-following.
The temptation when attempting to fit renewables into the central station model is to develop them on a scale as similar as possible to that of traditional generating stations, connecting relatively few large installations, in particularly well-endowed locations, with distant demand via high voltage transmission. Renewables are ideally smaller-scale and distributed - not a good match for a central station model designed for one-way power flow from a few producers to many consumers. Grid-connected distributed generation involves effectively running power 'backwards' along low-voltage lines, in a way which often maximizes power losses (because low voltage means high current, and losses are proportional to the square of the current).
This is really an abuse of the true potential of renewable power, which is to provide small-scale, distributed supply directly adjacent to demand, as negative load. Minimizing the infrastructure requirement maximizes the EROEI, which is extremely important for low EROEI energy sources. It would also minimize the grid-management headache renewable energy wheeled around the grid can give power system operators. Nevertheless, most plans for renewable build-out are very infrastructure-heavy, and therefore energy and capital intensive to create.
Both wind and solar are only available intermittently, and when that will be is only probabilistically predictable. They are not dispatchable by system operators. Neither matches the existing load profile in most places particularly well. Other generation, or energy storage, must compensate for intermittency and non-dispatchability with the flexibility necessary to balance supply and demand. Hence, for a renewables-heavy power system to meet demand peaks, either expensive excess capacity (which may stand idle for much of the time) or expensive energy storage would generally be required. To some extent, extensive reliance on power wheeling, in order to allow one region to compensate for another, can help, but this is a substantial grid management challenge.
Little storage currently exists in most places, although in locations where hydro is plentiful, it can easily serve the purpose. Where there is little storage potential, relatively inflexible existing plants may be required to load-follow, which would involve cycling them up and down with the vagaries of intermittent generation. This would greatly reduce their efficiency, and that of the system as a whole, reducing, or even eliminating, the energy saving providable by the intermittent renewables.
Not all renewables are intermittent of course. Biomass and biogas can be dispatchable, and can play a very useful role at an appropriate scale. EROEI will be relatively low given the added complexity and energy input requirement of transporting and/or processing fuel, and also installing, maintaining and replacing equipment such as engines.
Biogas is best viewed as a means to prevent high energy through-put by reclaiming energy from high-energy waste streams, rather than as a primary energy source. This will be useful for as long as high energy waste streams continue to exist, but as these are characteristic of our energy-wasteful fossil fuel society, they cannot be expected to be plentiful in an energy-constrained future. The alternative - feeding anaerobic digesters with energy crops - is heavily dependent on very energy intensive industrial agriculture, which translates into a very low EROEI, and will not be possible in an energy-limited future scenario.
Smart grid technology, large and small scale energy storage, smart metering with time-of-day pricing for load-shifting, metering feedback for consumption control (active instead of passive consumption), demand-based techniques such as interruptible supply, and demand management programmes with incentives to change consumption behaviour could all facilitate the power system supply/demand balancing act. This would be much more complicated than traditional grid management as it would involve many more simultaneously variable quantities of all scales, on both the supply and demand sides, only some of which are controllable. It would require time and money, both in large quantities, and also a change of mindset towards the acceptability of interruptible power supply. The latter is likely to be required in any case.
Greater complexity implies greater risk of outages, and potentially more substantial impact of outages as well, as one would expect structural dependency on power to increase enormously under a smart-grid scenario. If many more of society's functions were to be subsumed into the electrical system - transport (like electric cars) for instance - as the techno-utopian model presumes, then dependency could not help but be far more deeply entrenched. In this direction lie even larger technology traps than we have already created.
In Europe, where indigenous fossil fuel sources are largely depleted, there has been a concerted move into renewables in a number of countries, notably Germany and Spain, since the 1990s. The justification is generally climate change, but security of supply plays a significant role. Avoiding energy dependence on Russia, and other potentially unstable or unreliable suppliers, by developing whatever domestic energy resources may exist, is an attractive prospect. Public policy has directed large subsidies into the renewable energy sector in the intervening years.
Feed-in tariffs, offering premium prices for renewable power put on to the grid, were introduced, with different tariffs offered for different technologies and different project sizes, in order to incentivize construction and grid connection of all sources and sizes of renewable power. In addition, in a number of jurisdictions, grid access processes have been streamlined for renewables, and renewable power has preferential access to the grid when the intermittent energy source is available. Other power sources can be constrained off if insufficient grid capacity is available.