World Energy Outlook 2007

Technologies involving the absorption of CO 2
in solvents and subsequent
solvent regeneration, sometimes in combination with membrane separation,
are the most prevalent.
The oxy-combustion process: This involves the combustion of fossil fuel in a
mixture of near-pure oxygen and recycled flue gas, producing a secondary flue
gas stream consisting essentially of CO 2
and water, which can then be
separated.
CO 2
capture from combustion processes is highly energy-intensive and
expensive. Separation of CO 2
from natural gas at the well head is necessary to meet
quality standards and offers a cheap source of CO 2
for storage (Box 5.4). CCS in
power generation is cheapest for large, highly efficient coal-fired plants. The capital
cost of a demonstration power plant with CCS is estimated to range from $0.5 to
$1 billion, 50% of which is for the capture and compression equipment alone.
The typical cost of CCS in power plants ranges from $30 to $90 per tonne of
CO 2
, but costs can be much higher depending on technology, CO 2
purity and
site. The cost of retrofitting CCS equipment on an existing power plant is
currently thought to be much higher per tonne of CO 2
abated than the cost of
equipping a greenfield power plant. No large coal-fired power plant with CCS has
yet been built, though a large number are at an advanced planning stage.
CO 2
is most commonly transported by pipeline, as this is the most cost-effective
mode over distances of less than 1 000 km. The cost depends on the terrain,
pressure requirements, distance and capacity. There are very large economies of
scale. For a 250-km onshore pipeline and over 10 Mt of CO 2
transported per
year, costs are currently of the order of $1.50 to $4 per tonne of CO 2
(UK-
DBERR, 2007). Storage costs vary enormously, according to infrastructure
requirements (new injection and monitoring wells or retrofitting existing
facilities), volumes to be injected, injection depth and whether the CO 2
is used
for enhanced oil recovery. In the case of enhanced oil recovery, the net cost of
storage can be negative. In other cases, costs may be up to $10/tonne for onshore
aquifers and $40/tonne for depleted offshore oil and gas fields (UK-DBERR,
2007). Offshore storage is generally two to three times more costly than onshore
disposal. Monitoring costs depend on the risk of leakage; they are estimated to be
generally less than $1 per tonne of CO 2
injected.
Using cost-effective technologies and favourable siting, the lowest costs
achievable for CCS at greenfield coal-fired plants are currently estimated to
be of the order of $50/tonne (IEA, 2006b). This includes capture costs of
$20 to $40/tonne, large-scale transportation by pipeline costing $1 to
$5/tonne per 100 km and storage costs of $2 to $5/tonne. Short-distance
transport and storage together might cost less than $10/tonne, if monitoring
costs are small. Assuming reasonable rates of technology learning, the total
cost of CCS might be expected to drop to below $25/tonne of CO 2
by 2030
(IEA, 2006c).
218 World Energy Outlook 2007 - GLOBAL ENERGY PROSPECTS: IMPACT OF DEVELOPMENTS IN CHINA & INDIA