Renewable energy: the pros and cons of green power

November 27, 2013 by  
Filed under Green Energy News

THE UK needs to double the amount of electricity it generates from renewable energy if it wants to meet its targets for 2020. Between April and June this year, green energy sources accounted for around 15.5 per cent of electricity but this needs to increase to 30 per cent in the next seven years. The government claims it is making “very good progress”, with £31bn worth of private sector investment in renewable electricity announced since 2010 and hopes that green energy will play an important part in keeping British lights on. Here is where we are now:

WIND

The force of the wind is used to rotate turbine blades connected to a generator. Wind turbines have traditionally been located onshore but are increasingly being built offshore as well.

How much we use now: Wind power accounts for 7.5 per cent of electricity generation in the UK, according to the latest government statistics. And RenewableUK says there are currently more than 5,100 operational turbines operational in the UK.

Targets: The government wants to increase offshore wind capacity from around 3.7GW to 16GW, and onshore wind capacity from 6.7GW to 13GW by 2020.

Overseas comparisons and new projects: China, the US and Germany have the largest capacity for wind power, with the UK coming sixth on the list. Around 960 turbines are currently being built in the UK, with 2,711 turbines approved for construction. Npower claims to be building Europe’s largest offshore wind farm, Gwynt y Môr, off the coast of North Wales.

Pros and cons: Wind power is relatively affordable but turbines only turn when the wind is blowing strongly enough. Offshore wind farms are more expensive to build, while onshore farms are often criticised for ruining the beauty of the countryside.

Cost: The draft strike price – a state-backed guaranteed minimum tariff for electricity – for onshore wind projects is £100/MWh for 2014/15, falling to £95/MWh by 2018/19, while offshore wind projects will qualify for £155/MWh in 2014/15, falling to £135/MWh by 2018/19.

SOLAR

Energy from sunlight is harnessed for power using crystals made from material such as silicon that produces an electrical current when struck by light.

How much we use now: Combined with wave and tidal power, solar accounts for just 0.5 per cent of all electricity generation.

Targets: Officially, government plans to reach 10GW by 2020, the equivalent of powering around 7 million homes, but Gregory Barker, the energy and climate change minister, says he is aiming for 20GW before 2023.

Overseas comparisons and new projects: The country with the largest solar capacity last year was Germany, which had the capacity to produce 7.6GW of power, but China, the US and Japan are expected to overtake Germany next year. The UK came tenth on the list but is predicted to rise to seventh place by 2014.

Pros and cons: Energy from the sun will not run out, it does not give off carbon dioxide emissions and it is free. The sun does not however shine 24 hours a day and installing panels can mean a high upfront investment.

Cost: The draft strike price for large solar projects is £125/MWh for 2014/5, falling to £110/MWh by 2018/19.

HYDRO

Power derived from the energy of falling and running water.

How much we use now: Hydropower accounts for 1.2 per cent of all electricity generation in the UK.

Targets: The government expects hydropower to make only a modest contribution to the 2020 to renewable energy targets. Recent studies estimate that it can only increase by around 850MW to 1550MW.

Overseas comparisons and new projects: China, Brazil, the US, Canada and Russia have the highest hydro capacity. Together they account for 52 per cent of the world’s hydro capacity. Opportunities to use this technology on a large scale in the UK are now limited, not only because of environmental concerns but also because many of the most economically attractive sites for schemes have already been used. Although one recent project includes a hydropower station on the Thames in Berkshire, which helps power Windsor Castle.

Pros and cons: Unlike wind and solar power, hydropower is not an intermittent energy source. Once a dam is built, operational and maintenance costs tend to be low. Upfront costs can be high though and it does carry risks of major flooding and environmental damage if not managed properly.

Cost: The draft strike price for hydro projects is £95/MWh for 2014/15 to 2018/19.

BIOENERGY

Bioenergy comes from plant and animal waste. For example, wood or manure might be burned to produce energy.

How much we use now: Bioenergy accounts for 6.3 per cent of all electricity generation.

Targets: Government analysis suggests that sustainably-sourced bioenergy could contribute to around eight to 11 per cent of the UK total energy demand by 2020. However, the government admits that the estimate is “highly uncertain”.

Overseas comparisons and new projects: In 2012, the US had the largest installed biomass capacity, followed by Brazil and China. The UK came ninth down the list, behind Germany, Austria, Sweden, India and Italy. According to The Guardian, eight biomass power stations are operating in the UK and a further seven are in the pipeline, but none operates near capacity.

Pros and cons: It makes use of waste, which is rapidly increasing in many parts of the world, so has economic and environmental benefits. But unsustainable biomass could lead to deforestation and even more greenhouse gas emissions. Increased biomass would also mean large land requirements, which leaves less land for food production.

Cost: The draft strike price for biomass conversion projects is £105/MWh for the next six years.

WAVE AND TIDAL

A generator is driven by the motion of natural waves or currents flowing in and out of tidal areas.

How much we use now: Combined with solar, wave and tidal power accounts for just 0.5 per cent of all electricity generation.

Targets: Wave and tidal stream energy has the potential to meet up to 20 per cent of the UK’s current electricity demand. The government predicts that up to 300MW of generation capacity could be deployed by 2020, the equivalent of providing energy for 210,000 homes, and 27GWs by 2050, equivalent to powering 18.9 million homes.

Overseas comparisons and new projects: The UK is said to be a global leader in wave and tidal power, with more wave and tidal stream devices installed than the rest of the world combined. The industry is still in its early stages though. Plans under consideration include a tidal lagoon in Swansea Bay and a tidal barrage across the Severn estuary.

Pros and cons: Tides and waves are predictable but harsh environment and extreme weather conditions make building, deploying and managing a fleet of tidal machines a dangerous challenge.

Cost: The draft strike price is £305/MWh for both types of power for the next six years. · 

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