Let’s get real about renewables

Updated on: Jan 27, 2018


Despite falling costs, solar and wind cannot replace coal in supplying baseload power. Hence, focussing on clean coal is crucial

The recent frenzy in renewable energy, particularly in the solar space, has raised expectations of coal-free, sunshine driven power for India at the lowest cost in about a decade’s time. The impetus for renewables is certainly the right step for coping with climate change challenges. However, we have to be realistic in our ambitions and base our plans on science and sound economics rather than hyperbole and rhetoric. Zero carbon renewables is the eventual goal, but in the foreseeable future coal seems to be the only option for reliable 24X7 power at less than ₹3 per unit. Solar and wind will be an increasing and growing complement to our conventional energy sources, but is unlikely to be our primary source of power for quite some time.

Over-optimistic targets

While the Government’s intent of 175 GW of installed renewable capacity by 2022 is admirable, what we need to ask is what is plausible, based on our understanding of technical, economic, political and market structure dynamics. Unfortunately, contrary to claims of popular science we will not magically transform ourselves into a world of carbon-free renewables in a decade or so — more so in the developing world. One must understand that energy technology has its own time constants and everything does not follow Moore’s law .

It took coal (1815 onwards), oil (1915 onwards) and gas (1930 onwards) 60 years to get to be the world’s major share of energy supply. Carbon free renewables are at the 5 per cent stage today. Similarly, the 100GW of planned solar capacity addition by 2022 will mean an addition of 18GW of solar capacity per year — which is certainly aggressive at the current stage of solar development.

The financing issue is also particularly problematic, as the estimated $170 billion in investment is, in all likelihood, beyond the capacity of the domestic financial sector even with subsidies. Attracting international capital competing for similar energy technologies worldwide introduces new challenges.

Constraints to renewables

The world’s obsession with the falling cost of solar and the elusive quest for grid parity — meaning renewable power cost at or below the current cost on the grid — has clouded our thinking. Firstly, cost is not the only factor, which determines the suitability of solar, and renewables for what is known as baseload power. Apart from affordability and climate impact, availability, reliability, consistency and feasibility are key determinants of 24X7 power for industry and consumers.

It is important to understand that, physics places fundamental limitations on the power generation ability of solar and wind. In what is known as power density in energy science — how much power you can produce per square meter of effective area used —there are orders of magnitude difference between solar and conventional sources like coal, gas and nuclear.

While coal and nuclear have a power density ranging from 300-1,000 watt per square metre of effective land area, solar has only 6-12 watts and wind about 3 watts. So, if we plan to put up a large utility scale solar plant, we will need very large land areas. For a 640-MW solar plant, the area roughly needed is about 10x10 km. If we aim to meet the total requirement of utility scale power through renewables, the requirement of land will likely be beyond our ability to mobilise in a reasonable time frame, and in an economically viable manner.

While government subsidies and programmes such as solar parks help in seeding the market, developing large utility scale solar requires very large land banks in areas with high solar irradiance intensity in order to support competitive tariffs. In fact, the latest study by Lazard, indicates that the effective power cost through solar will be likely not less than ₹5 per unit.

The weather factor

Secondly, nature places some hard constraints on solar and wind, and that has undesirable effects on harnessing solar energy in an effective manner through the grid. Wind and solar both depend on weather conditions, and are both variable and uncertain. Solar plants run at 50 per cent effective capacity, since you can’t run them in the night.

Solar also has the problem of intermittency due to cloud cover and rain, which further reduces effective capacity. The grid was designed for “dispatchable” power on which you have control. The original grid was not designed keeping uncontrolled intermittent power load of renewables in mind and this means that the grid needs to be re-engineered over time to support renewables without compromising baseload power supply. Unless very large grid scale battery storage is available in the near future economically, we will need to have backup capacity based on thermal power to augment the variability and uncertainty of renewables. This will unfortunately increase the power cost to support renewables, as has happened in Germany.

In a developing country like India — and the world for that matter —clean coal technologies, energy efficiency and energy use complemented with renewables has probably a far larger and quicker impact on making available, affordable and reliable 24X7 power, while abating carbon emissions and conforming to climate change goals.

For cleaner coal

India today has 200GW of coal power, which uses mostly subcritical technology —spewing a tonne of carbon dioxide per MWh generated. With the right carbon reduction incentives and investments we should be able to induce accelerated adoption of economically attractive low carbon coal technologies like supercritical, ultra supercritical and, possibly, coal gasification for power generation. So, by 2035 when our capacity likely expands to around 500GW of coal power plants, emissions should come down by a third. The resulting carbon emissions will be lower at the higher thermal power capacities than what it is today.

India’s energy poverty challenges with consumption at just over 1,000 units of electricity per capita — compared to China at over 4000, Europe at 6000 and US at 12,000 — are enormous indeed. We must engineer practical solutions to this energy challenge with conventional and renewables. The war should be on carbon emissions, not coal.

The writer is President of MN Dastur & Co. The views are personal

Published on June 19, 2017
This article is closed for comments.
Please Email the Editor

You May Also Like

Recommended for you