How Much Energy Can We Have From Renewables
How much electricity can we have from renewables? According to an estimate by Department of Trade and Industry detailed in their 1994 Energy Paper 62 (DTI 1994), we can in principle economically avail of up to a maximum of 190 TWh/yr of renewable electricity by 2025, or around 63% of current consumption, at around around 4.5 p/kWh at 15% discount rate. This however, represents maximum estimated resource that might be largely impacted by a range of technical, environmental and economic constraints when translated in practical terms. The Renewable Energy Advisory Group of the UK Government however made a fairly conservative estimate according to which it was quite possible to achieve a 20% contribution to electricity by 2025 (60 TWh/yr). This would involve around 10, 000 MW (net) of renewable generating capacity.
The renewable energy technology is being constantly developed for performance, reliability, and cost effectiveness. The future of renewable energy is optimistic. Within a decade for instance, the cost of electricity from wind sources has fallen by around 70 percent. Reductions in similar range have also occurred for photo voltaic cells.
There are nonetheless technical constraints. Renewable sources like wind, wave, and sun as is well known are intermittent. However, intermittency do not pose severe challenge as suggested, if electricity from these sources is fed into national power grid network. The grid can even out local variations if the total contributions from various intermittent renewables do not exceed 30 to 40 percent of the total electricity on the grid. There would be no need therefore for expensive storage systems as the overall power available from the grid will remain more or less constant.
The other constraint that renewables could face involves varying degree of local impact. In other words, local environmental, land use and planning factors are open to debates, controversies, and disputes. In fact, there have already been local planning disputes and local oppositions to wind farms sited across the UK as will be discussed shortly.
Indeed the stimulus for deployment of renewables comes from increasing environmental concerns over the global environmental impacts – emissions of greenhouse gases from burning of fossil fuels – of using conventional energy technologies. The scenario calls for trading off local and global impacts against each other. Therefore, a number of other related factors enter the issue including such factors as technical, economic, environmental, and political, apart from national and international policy concerns.
Some of the issues that the UK will need to address include: whether nuclear power can be a reliable future source of energy? How will the nation tackle the security of supply and the balance of payments problem if and when she has to import natural gas? The extent and modalities of energy conservation? Over and above, there are issues like impacts of greenhouse gas emissions such as depletion of ozone layer, and acid rain etc that are universal concern.
In comparison to several other nations, the UK fortunately enjoys bounteous reseves of coal, oil and gas. This has probably made her complacent on the issue of conservation. The two factors – relatively large reserves of conventional energy sources and their cost effectiveness – must be weighed against the finite stock of the fossil fuels as well as the environmental problem they may cause in terms of global warming.
A two pronged approach calls for energy conservation through efficient technologies on one hand and developing renewables on the other to meet the EU and international targets. New technologies promise to drastically cut down emissions through efficient use of fossil fuels. This would take care not only of emissions but also the cost as well as consumption per unit. These technologies claim to save between 50 to 80 percent in many end-use sectors. This could be our strategy in the short-term energy conservation. Nonetheless, the UK will still need new sources of energy as the old and ailing plants are retired. The renewables are the most promising option for the UK since revival of nuclear power is frought with controversies.